Are you looking for a more cantankerous version of this video where I go over more of the experimental design, with 138% more runtime and 75% more snark? Then the main channel video's got you covered! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DTsQjiPlksA.html
@@linuxgeex Nah. For one, you're missing that the design conditions only showed up for ~36 hours total this year. And when we're talking about heat pumps, where the compressor only gets lubrication when it's running, shorter cycles are actually _bad_ for them. Short-cycling kills equipment, and that's what my furnace is doing all the time. It's less bad for the furnace, to be sure, but it's absolute hell on a compressor. And as I said - you need to get comfortable with there being secondary heat sources. That provides the margin.
Any chance you might be able to do an HVAC video on apartment heating and cooling? I.E. more specifically HVAC where you're not allowed to make any physical changes to walls or ducting, and or perhaps options for heat pump style window heating/cooling systems. I know you did a video on portable air conditioners and your hate for them, but perhaps more on figuring out what kind of output you need based on the size of the apartment, and perhaps on window units that actually function as a heat pump since there are a few that do.
The efficiency of smaller heatpumps are higher reaching a COP of 5 at the rated output than larger ones are going to be closer too 3 or 4 at best. The reason for this is that not everything is suitably upsized and therefore the efficiency suffers. But what is the COP when not running hard out??? Turn out if running lightly while these numbers are never published a larger heatpump running on low power can have a COP well above 5! And so the more hard out a heat-pump has to run the more you pay for the same heating (or cooling).
I am very impressed how Alec didn't just chop pieces of the video out, but wrote and produced a seemingly almost completely separate script and filming session.
I was initially just going to put this on with the volume down to give him the algorithm boost of engagement and watch time, but then I realized that it does, indeed, appear to be a whole new (if _very_ similar) video!
I’m so glad you made this condensed version, I love the big main video but it would be overwhelming to my mom who plans to get an AC unit to replace her swamp cooler and I’ve been trying to talk her into getting a heat pump
Yeah this mid-length is great for sharing... and putting it on a different channel is the right move. I really wish RU-vid would allow channels to publish multiple sub-channels so we could separately subscribe to topics and formats... for the most part I would use it to avoid the Shorts... like Integza putting out 3 related "I did a " Shorts a year or more after the video they reference. Ugh! So yeah, this channel is awesome, and if you do Shorts, please make them a 3rd channel.
@@RomanShein1978 I immediately switched here when he pointed out the length of the main video, and even 26 minutes is longer than I normally prefer for single-topic videos. But his content is always worth the time.
Good luck, I thought I had convinced my parents on installing heat pumps for their home remodel, but they balked once they got quotes from some HVAC contractors. It's a huge missed opportunity in futureproofing, as we live in the Bay Area where we don't need much heating capacity and where some cities have started phasing out gas appliances.
Most people aren't going to understand this, but for a Midwesterner, that Google rant was _pure unmitigated rage._ I'm surprised his hair didn't catch fire or something.
Wait is that a Midwest thing? I so heavily just *felt* that frustration but I thought that was an everyone thing? Please enlighten me I'd love to know about this.
I just went through this in the last two years. I had a ~75,000 BTU furnace and a 4 ton AC. It was time to replace and everyone wanted to replace with same same or go bigger. I finally found an HVAC contractor that did the calculations and showed his homework to prove it. Taking into account all my home upgrades, he calculated that I only needed a 40,000 BTU and a 2 ton AC. I was very skeptical but the math doesn't lie. This saved me a bunch of money and I was able to change my 40 AMP breaker for AC to a 20 AMP. It continues to save me money on my electric bill. You are right, on the coldest and hottest days it runs just about constantly. BUT IT IS DESIGNED THAT WAY. And those extremes are only a very few days a year. Make your HVAC contractor do the Manual J and make them show you their homework. Most will just walk away because they don't want to do the work. Those are contractors you don't want working for you anyway.
A smaller unit shouldn’t save (much) money on your electric bill; it still has to do the same amount of work, just spread over a longer period. (Yes, there are some losses due to a larger unit short cycling, but they shouldn’t be significant.)
@@k5sss assuming a single-speed compressor rather than 2-stage or variable speed compressor, and assuming the same runtime (work-hours) smaller unit draws far less current when it's running than the larger unit. a larger unit with variable speed should be comparable to the single-speed smaller unit in this example though right?
@@Robin-xe4yzIf the larger unit is drawing more power, then it’s running for proportionately less time, so the total work done is (about) the same. Multi-stage and variable-speed units are designed to act like a smaller unit when that’s all that’s needed. That prevents short cycling but doesn’t change the total work being done.
My apartment's maintenance guy is overworked and busy as hell, but thankfully he's an ABSOLUTE DORK about stuff like this. Just did this for our water heaters (i hear he vetoed the company's idea for on-demand heaters,) AND solved the moisture problem in our basements by putting condensers on them. The world needs more folks like him.
You having any hot water issues or weird symptoms? Our basement was way more humid when our venting seemed to be working the worst and it was hard to recognize it was from lack of air and/or some vent restriction. When symptoms were worst for us, it was way more humid than normal in the basement room w/ it and the only time winter humidity was a problem for us. The combustion exhaust apparently has quite a lot of water, even for the low output of a 36k BTU water heater, and it made a huge difference when I'm pretty positive it wasn't venting properly if at all. When it worked normally, there wasn't any real humidity introduced and there shouldn't be
@@Demoralized88 We're all electric with no central heating or anything, so I'm not sure our stuff applies to your situation. Also, I'd have to ask Dave, I don't know much about troubleshooting anything that doesn't have an operating system 🤣
There was a *125,000* BTU/hr gas furnace installed in my ~1800 sq ft house when I bought it. It was replaced with a 70,000 BTU/hr two stage furnace that almost never runs on the second stage. The only time stage 2 was necessary was the day after you mentioned in 2022 when we got the same cold blast in Ohio. Even then it didn’t run full blast for more than a couple hours. Yep, my system was also oversized by 3-4x!
Our ~1900 sq ft house currently has a 115,000 BTU/hr gas furnace. The longest it has ever run in the winter during a single 24hr period was for 9hrs when the outdoor temp averaged 8 degrees Fahrenheit. Definitely overkill.
One note of caution on kill-a-watt style energy monitors... they usually aren't designed to actually be able to handle high wattages for hours at a time. They tend to overheat and start melting the plastic casing. The problem isn't the shunt, instead it is the typically low-grade plug receptacle. I had this happen to one of mine while I was monitoring a mere 700W of power for 4-5 hours a day. After about a month I took it out and realized that the plug was somewhat stuck in the receptacle and the plastic looked a bit melted and brown on the unit. It hadn't caught fire but the plastic obviously over-heated. I ripped the sucker apart so I could get a good look, and It turned out to be oxidation of the contacts in the plug receptacle combined with relatively flimsy contacts. The area the unit has been installed in was clean, but the low quality of the device meant the manufacturer had cut corners. I no longer use my kill-a-watts to measure high amounts of power unattended. -Matt
@@superslash7254that's great to know about. The other option is something like Emporia, installed in the main panel with multiple non-contact sensors (CTs) to monitor multiple circuits.
The thing you learn by watching the Home Performance channel on RU-vid is that heating and cooling is only one dimension of the problem, and that taking care of the humidity is a second dimension that many people don't know about, much less do anything to address. And humidity can lead to huge problems in many areas, including mold and mildew growth, which can be a huge health problem. I'm glad you touch on it in this video, and doing a Manual J calculation, but I'd like to see you talk more about how important it is to control humidity.
I had to basically beg my HVAC installer to put in an undersized furnace when we upgraded from gas furnace+AC to gas furnace+heat pump. "Don't worry, in winter, the top floor stays plenty hot from heat rising, we'll shut off the vents to the top floor in Winter; likewise the basement stays way too cool in the summer, we'll shut it off. It'll only be heating/cooling 2/3 of the total volume of the house at any time." He finally agreed. And then we got a free upgrade (not in capacity, but in capability) because Lennox became so backordered they couldn't deliver the smaller-capacity, medium-capability one we wanted. So instead of a 2-phase, we got an "variable phase" (aka: it can produce exactly the heat/cooling level needed, instead of "FULL BLAST FOR A FEW MINUTES then off.")
I just noted this same consideration..... that systems can be had, and likely will become more developed out; that modulate the output to the granular data going in..
@@gg-gn3re That would be nice if zoned HVAC could do that. All I have are manual baffles in the utility room to enable/disable the registers in the basement and top floor. (Separate baffles for the two floors - the main floor stays open at all times.) I know there are more granular zoned systems, or even multi-mini-split systems that can move refrigerant between rooms to do that, but they’re expensive.
@@AnonymousFreakYTYea they are, I was being literal. Run a separate duct entirely from your system and then just have some switch to turn it on/off it's likely you'd want it on almost 24/7 so I'd just run it separate. As you say there are systems that can handle this kinda thing but they're 10x the price
As an HVAC-R technician, thank you for pointing out these issues that this industry needs to address by training techs to do manual J, sizing equipment properly, and not being salesmen first, would do so much to help move the industry forward in a more efficient direction. I'm working on starting my own business this year (hopefully), and I have the same mentality as you, more pumping, more now, at reasonable prices.
@rogerk6180 While that may be true, by offering more efficient units and service, you would, in the long run, earn more from repeat customers rather than the highway robbery some companies are responsible for these days. I see what the company I work for charges for almost every job I run, and it's nauseating at best what they get away with charging in most cases.
@rogerk6180 It's the mindset that needs to change, and unfortunately, that's far easier said than done. That's why I hope to make a small ripple in the big pond of companies in my industry, it might not do much, but it could start things moving in the right direction if enough people start talking about it.
@@joshengelbrecht1310 the problem is people no longer want to know anything anymore. All they know is more bigger and more expensive is better and having more expensive is more bragging power. Picking the cheaper option must mean it is worse or it makes you a cheapskate. So the one who offers you the biggest and more expensive option must be the better option. And companies are more then willing to accomodate that. In the past people had at least some superficial knowledge about most things and thus knew what they needed and where looking for. Most people can't even put up a lightbulb anymore it seems and are so conditioned that everything is some complicated safety risk that it needs some high payed profesional to do it. Even though most things are done by random dudes that are sent over as a profesional that barely know the right end of a screwdriver themselves. I see a lot of americans moving to the netherlands where i live, and how many basic home tasks they request a "contractor" for that are just simple things every single person here knows how to do themselves in 15 minutes is shocking. I imagine your grandparrents did these things themselves around the house as well, but somehow culture shifted where this skill was lost or made to look so scary that people are de-incentivised from doing them themselves. The amount of light fixtures i put up and shower heads i have replaced for bewildered american neighbours is just shocking lol. That is something your dad teaches you how to do when he does it at home or the first time you move out of the house here in the netherlands. There is a cultural difference for sure. Ignorance breeds exploitation. If you have no idea what a job actually entails and seems mighty difficult you can basicly ask what you want to do it for other people.
As an hvac master myself, in upstate NY, a lot of manual J up here are way undersized lol. Not the other way around. I had one set of plans with Emmanuel J that said they needed a 40000 BTU furnace for 1600 square feet of house. Yeah right. You're not taking into consideration air exchanges, dehumidification, and enthalpy. I do see a lot of oversized equipment out there though. Good video!
I can one up you on this one big time. I just bought a home in Sonoma County (about an hour north of SF in California). Even being a 1940's home with no attic or crawl space insulation, Manual J calls for about 32,000BTU of heating need. Drops well below 2 tons once the crawl space is addressed, and down to about 1.5 tons when the attic is sorted. Someone actually installed an 84,000BTU furnace on this house... it was so oversized that there is evidence that it caught itself on fire at one point. There was a 90 degree temperature delta (Furnace was blowing 155 degree air when inside temps were 65 inside the house). The only reason I noticed it was so bad was I switched out my battery powered thermostat for an Ecobee which takes its power from the C wire. The furnace was tripping its own overheat sensor every 20 minutes and shutting down the thermostat. People really need to know more about the basics of HVAC, what Manual J is, and the benefits of heat pumps. People also need to know enough to ask questions of their HVAC professionals, there are a lot of very smart, very good people out there doing good work... there are also a lot of folks who measure with their thumbs and are more interested in being done in a single day and never having to come back rather than doing a good job...
I have the same issue, our house is 1200 sq ft. and the last owner had an HVAC professional install a 60,000 BTU furnace for this small house, completely overkill. I installed an ecobee and the same thing happened to me, it would restart everytime the heat turned on it felt like. I had an HVAC tech out to take a look and they advised me that the furnace is WAY too large for the house and that eventually my heat exchanger will crack and fail due to the system overheating constantly. I'm in Ontario Canada, but even here it feels like the winters are getting milder and milder. So now I need to shell out for a new smaller furnace or just bite the bullet and install an appropriately sized heat pump instead.
@@Airseas TL;DR find a professional who understands heat pumps/Manual J load calculations and ask them about retrofitting your system for dual fuel and setting your furnace changeover point to a very low temperature (a really good tech will be able to recommend that temperature based on your region and gas vs. electric energy costs). The long story: Check out the rest of his HVAC videos. All the info is really great. You don't need to replace your furnace, you can get an appropriately sized heat pump (outside unit) and put an A-coil on your furnace and just use the furnace as an air handler. Gree makes a pretty affordable inverter heat pump that can be field installed as 2 or 3 tons that is designed to work with mismatched air handlers (it uses the temperature of the refrigerant as it comes back to the outside unit to vary how much output its sending). It's still not "cheap" and if you have a good/newish Air Conditioner then you are still stuck replacing something expensive... but if you happen to have an old AC ready to be replaced then this is a pretty cost effective way to adapt your oversized furnace to a much more efficient heat pump system. It'll never be as efficient as a fully matched heat pump/air handler/thermostat from like Mitsubishi or Fujitsu... but considering how much less it would cost to install, I think you'd still come out ahead until it's time to really put in a new system in 15-30 years. The unit I referenced is the Gree Flex (aka GE Connect aka Mr. Cool Universal). My house has a GE Connect using the 17 year old furnace as a vestige air handler (we had the gas line turned off). We never get below 25 degrees outside, so ymmv but it never runs more than 1 hour a day here so even IT is oversized for us.
Not only was your furnace oversized, but apparently the duct work was way undersized for that furnace as well. Probably noisy too. A 90 degree delta for a scorched air system is about as unprofessional as it gets.
@@jamesnasium7036 yeah it was pretty bad. Luckily the previous owners had installed a heat pump as an air conditioner only. Got someone to come rewire it for heating and cooling and we are using that ridiculous furnace as an air handler. It’s not perfect but it’s safe and works a hell of a lot better.
Hot water baseboard system here, in northern Pennsylvania. Temps rarely get below 0°F and VERY rarely down to -15°. The old system was a 140k BTU monster and maybe in the 70% efficiency range. We replaced the windows, reinsulated the walls, and added insulation in about 2/3 of the attic; the new boiler is 90% efficiency 80k BTU, and also heats the domestic hot water. If one or both of the thermostats are calling for heat (and the HW tank isn't), it checks the outdoor temp, and the water temp coming back from the house on the return side, and does some of that "math" stuff to determine how hot the output water should be, and fires the modulated burner accordingly. When it was first set up, with a low-end design temp of -15°, on a 0° but windy night, it couldn't keep up - the temperature curve had it still holding back a little at 0°, and the house couldn't get above about 63-65°. I reprogrammed the curve to ramp up to full throttle as it approaches 0° instead, and that did the trick.
I'm in Canada and love my cold climate heat pump. We have 15 kW of backup heat strips which I'm now thinking are wayoverkill and they have yet to be used despite outdoor temps dropping to below -30 last year. They definitely didn't get used this year as we barely had winter. Heat pumps are amazing. Highly recommend!
We replaced just the outside unit with a heat pump. I think the retail price of the unit was about $3-4k. Our HVAC installer charged us $9,000 and it took an understudy only 4 hours to complete. More attention is needed on the price gouging in the industry and the lack of willingness to provide fair pricing. That said, we saved a good $15k by not also upgrading the attic unit (blower). Replacing it would have necessitated 240V wiring and another breaker. We kept our gas furnace and have dual fuel with gas as the backup. We have a 3 ton unit for a 2,600 sqft modern home in California. Every calculator online seems to think I need a 4-5 ton unit, which to me is absurd. I don't think our heat ever ran more than 2-3 hours in a single day this winter.
You can't buy a furnace or a heat pump without going through a licensed HVAC dealer.. It's literally illegal in most states.. It's common in all of the building trades for the contractor to double their money on equipment and material sales.. Plus, charge for installation of the equipment and materials they sold you.. That's just the way it works.. If you don't like it, spend 4 years doing an apprenticeship, tens of thousands of dollars on tools and equipment.. Pass all of the test you have to take to get licensed.. Then spend 3 or 4 days crawling through your crawlspace and attic to do the install yourself.. I'm an HVAC technician.. There's a lot of overhead involved that we can't charge you for directly on the bill.. We don't make as much money as people think..
@@MarkLada My HVAC guy (owner of a 3-person company) lives in a million-dollar house and has a collection of classic cars. He does just fine with his profits.
@KiwiandPixeltheParakeets There's too much competition to over inflate bids like that.. You wouldn't stay in business long at all that way.. A couple of hundred dollars can be the difference between getting a job and not getting a job.. Especially if it's a municipal contract or commercial job.. We make a good, honest middle class living, but we have to work our tails off and sacrifice our bodies to make it.. I guarantee you most people wouldn't go in some of the places I have to go into on a daily basis.. Crawlspaces so tight you have to drag your face on the ground to crawl through them.. Attics so small that you have to lay across 2x4s and work on your side all day.. Just wait, if you think HVAC stuff is expensive now.. The government keeps imposing stricter and stricter regulations on us.. Equipment prices are going to more than double in the next few years..
@@MarkLada Maybe you don't make much as a technician, but your company owner is probably raking it in at your expense. Perhaps with all that training it may behoove you to go into business for yourself. Just a suggestion. None of what you said negates the fact that HVAC owners are absolutely raking it in with sky-high pricing.
I worked in the oil heat industry for many years. Everything you said is exactly what we attempted to teach our customers. We always did load calculations and more times than not recommended replacing old units with smaller more efficient units. People have been brainwashed that "bigger is better". Design load is immensely important, especially for cooling. Short cycling the AC means you're not dehumidifying the air. Half the work of AC "should be" dehumidifying. You'll feel comfortable at a higher temp if the humidity is lower. The same holds true for heat except you want to introduce humidity. If you have a humidifier installed onto the heater but it short cycles, you're not benefitting from the humidifier as much as you could be. As you stated, you want your HVAC system to run 100% (all day) when the temps hit their extremes for your area. In the Philly area we used 0F for heat and 100F for cooling. If your HVAC is cycling on & off on the most extreme days, it means you're literally throwing money away the entire time it's running... All year. Thanks for bringing so much good info to people who crave it.
Thank you so much for producing this video (and all your others too)! The shorter format, specifically designed for sharing is particularly useful. My 1100sqft 1940s single story house in a mild/moderate California climate came with a 3ton 36kBTU gas furnace, which only heated half the house in short bursts. Fast forward 7 years, $15k in overpriced “guesstimate sized” hvac with new ducts to the rest of the house, installed in a day, and was never commissioned correctly… and my home was still uncomfortable. As an experiment, two years ago I DIY installed a 1-ton 12kBTU VRF mini-split heat pump in the central room of the house and it’s capable of handling ALL MY HEATING AND COOLING NEEDS! It keeps my house comfy at 69degrees, and does so using 700-1000watts, near silently, and cost me < $1000 to DIY install (including buying all the tools). The $15k 3ton gas furnace with 14 SEER heat-pump system could technically sit idle or be removed. @Technology Connections - Ideas for followup videos - air sealing / insulation - oversized MERV 13-16 filters - IAQ - radon, CO2, particulates (PM2.5) I’ve fallen down a deep rabbit hole of knowledge that typical hvac installers are not trained/educated about. Thank you again for putting out all this content. The residential HVAC industry needs to get learning and implementing best practices quickly, so we can collectively move away from burning things for heat, save money, and all live more comfortable/healthy.
One other thing that cannot be understated is air leakage and window radiation, and how much of a dramatic difference it can make to the heating or cooling efficiency of your home. We live in a more mild climate and only have a reverse cycle air conditioner in our home (a.k.a. a heat pump). I reduced my power bills by at least 20% month for month from one year to the next by only adding tinting on the east and western facing windows along with redoing all the air seals on all the windows and the external doors and actually adding one to the attached garage. A downside to living in Australia is that a LOT of buildings over just do not take thermal efficiency into account and the building codes reflect that mindset.
I enjoyed this as well, and I can totally see why it is necessary. I like the rambly version more, but this is the one I'm going to send out to several friends who are looking at hvac upgrades in the near future.
@@TechnologyConnextras I agree that I find this more compact version more enjoyable, however I love the fact that you are offering both, mostly because for a topic that I care more about (like the pinball machine videos as I find it fascinating) I'll probably choose to tune into the longer format video
As someone who is a fan of the channel but doesn’t have any background knowledge in this field, I also like this video more because it’s a lot easier to follow.
My 1970's bungalow (*) in frozen capital of Hoth (Winnipeg) is heated with resistive electric forced air furnace. I've wired sensors everywhere. I can say with much certainty a single 5kW element will easily maintain my home at 20C through our coldest winters (to your point, it may not recover from a 3C overnight setback when it's -30C outside - but the temp won't drop). My 3x5Kw furnace rarely runs the 3rd element as it stages up (only when recovering on cold mornings ) (*) Walls are original 2x4 R12. Attic is R60 (thanks to recent utility rebates on insulation). Basement is R20 and windows are triple pane.
@@kimballwhite787 $225/ month. Switched when gas was all time high and hydro was less. Cost of high efficiency gas was more than double an electric. Switching from the original gas to electric did not increase my gas+ electricity bill. And I'm comfortable fixing an electric furnace in the middle of a cold winter night. Not comfortable touching a gas furnace with all its sensors and confusers.
The way that heat loss works, it will always be able to recover back to design temperature. It will take longer with less power, but it will get there.
I clicked on the link and got to the condensed version. Then you got me interested in the extended version, so I clicked on the link. Then you got me involved in the condensed version, so I clicked on the link.
1. Your heating/cooling system is sized for extremes, the coldest and hottest days of the year. So it will be "oversized" 360 days a year. Because if its not, the end user will complain. We wouldnt size them like that if we didnt need to. 2. Equipment goes by tonnage, a ton of cooling is 12,000 BTU per hour. Equipment models usually step up by 1/2 ton, sonetimes 1/4 ton a time. A house may only need an extra 500 btu an hour to meet the extremes, but the next possible size up may be 3k-6k more btus. 3. Modulating systems that can adjust capacity depending on need do exist, but they are more expensive. 4. If you want a "normal" size system, especially a heat pump, keep in mind that it may not keep up in extreme conditions, and you need to leave them on 24/7. If you turn the thermostat off at night or when youre at work, they will not be able to get back up to the desired temperature for hours.
Used to be, houses leaked a lot and were poorly insulated. The furnace had to overcome that or homeowners complained loudly. So massive oversizing was the norm. Nowadays, they are supposed to be well built, well insulated, and well sealed. But there are so many homes built to code minimum, that most arent correctly insulated, sealed, or even properly built. So they are still being oversized. Heat contractors arent being paid to perform a full house blower test and thermal imaging to see what it really needs. And then reccomend all the fixes be done as part of the install process. Take a thermal camera around your developement at night to see what it looks like. Then check older developments and single resident homes, apartment buildings, and even commercial buildings. (Old man grumble 1st thing in the am without coffee...)
The part of me that loves your stuff wants to listen to the full version but the part of me with things to do is happy for the condensed one. good job. now to fill the condenser with new refrigerant..
@@DaveTapley In short (and simplified because I don't quite remember) he was worried about pipes freezing in a crawlspace, as the air ducts wouldn't provide heat anymore and the space heaters are overkill for such a small space. So he added 100Watts of Christmas lights to provide heat (and festive atmosphere) to those places.
The reason why summer AC needs the same amount of power for a smaller temperatzre delta is humidity or more accurate the dehumidification that happens during cooling. As you covered there's A LOT of energy in the latent heat of vaporization and the same goes for the condensing part and that water from the evaporator doesn't go through another heat exchanger. In 99.9% of the cases that cold water will be dumped straight out of the house.
My new house got installed with a heat pump per my request thanks to your videos so thanks Alec! Having that unit also saved me a lot of space in my garage which is a huge bonus for me since I actually use my garage to store my car. I move in to my new home in about a month and I can’t wait to get all nerdy with my guests about my ac unit that I’m weirdly proud of.
The difference between the tonnage required in heating vs cooling mode and the outdoor ambient temperature is because temperature isn't the only heat load in your house. The people in it put off heat, your appliances put off heat, your electronics put off heat, and most of all there are direct and indirect solar loads that hit your house on a daily basis. This means you actually get a helping hand in cold weather but a lot more energy to reject in hot weather.
We in Holland use a gasheater to warm central heating water. I adjusted the temperature from 80 degrees back to 55 and the total output in kW back to 25%. Saves tons of gas, only takes a little longer to warm up the house.
same here, the factory default of our boiler is 75°C for the heating and 60°C for the hot water in the shower, like who the hell wants that hot of a shower?!?
@@GameCyborgCh Hmm, my boiler has a pre-mixer, this allows me to heat the water in the boiler to 75C and get away with just a 300 L boiler running for two of the cheapest hours of the day and still get enough hot water for three teenagers and a wife. :)
Great video! I thought I was the only one goofy enough to add up space heaters to verify how much heat pump capacity I needed! In addition to adding up space heaters, I also ran a Manual J calc for my house. Then I looked at the spec sheets for my heat pumps to make sure I'd have enough heat on my coldest nights. The mini-splits don't have backup resistive heating, but I do still have my science experiment space heaters in case I ever need them! You might have covered it in the longer video, but it's worth pointing out that heat pumps' output ratings are benchmarked around 35-40 degrees F. At 35 degrees F I have 34 kBTU/hr (about 3 tons) of heating. At -13F, I'd only have about 15 kBTU/hr (about 1.25 tons). In an extremely cold environment, that would be one reason to size the heat pump up.
I appreciate the shorter version! Sometimes I am deeply fascinated by a topic of yours but can’t quite commit to the beefy ones. I am LOCKED IN for this one
100% with you. When I bought my (now 115 year old) home, it had a 100KBTU/hr oil burner feeding steam, which was, generously, 75% efficient. Originally, the house had a central coal burner. The house was not tight, the windows were original, loose, and several broken, threr was little insulation. First thing was add insulation where easy and plug the big holes. I had no problem the first winter with a 22KBTU/hr ventless gas unit and a 1500W electric to back it up (don't judge me on the ventless unit. The house STILL isn't very tight despite 15 years of work). When I did the main system, I ran a manual J, got 44KBTU/hr, not considering the added insulation and replacing the windows. I put in an 80KBTU/hr, 96% efficient condensing hot water unit with panel convectors to replace the steam sectionals that also does domestic hot water with a 30gal tank. External sensor sets the firing rate based on outdoor temperature. The inspector (lets call him "Bob") wanted to fail me because the ruie is a replacement must be at least as big as what is replaced. He couldn't show me the rule. I showed him the calculation and he said that Manual J is BS. Those guys that wrote it don't know what they are doing. But if I want to be cold and have pipes freeze, it's my problem, and signed the tag. Never a problem. I can hold 75F when it is -15F with 30Kt wind. For 22KBTU/hr. And be able to shower, wash dishes, and do laundry all at the same time. I can't het pump, though, as I have a 60A service (from the post-WW-II upgrade) and there is no capacity for anyone in the region to upgrade. Don't get me started on the local utility....
Excellent video! As a homeowner than may need to replace my gas furnace soon, all this is good the know. I had an early model Rheem heat pump back in the late 70s, to augment my gas furnace, and unfortunately it was inadequate to heat my home below 35°F-40° F and I replaced it with a 3 ton A/C unit. Good to see the technology has gotten much better. Having a large 3 acre lot, I may also explore a geothermal system.
@dennissmith8199 - it is normal for conventional heatpumps to not be able to give enough heat much below freezing, those units are still very useful in shoulder seasons and worth getting instead of an a/c when doing equipment replacements. they are still made. there are plenty of mild days during the heating season. Cold climate heatpumps are loaded with electronics, that is the down side. this being said, a 70s heatpump would have been like 5 hspf and not worth running compared to gas, new ones start at about 8 hspf efficiency.
I'm a Hvac mans and leaning the Manual J and Manual S right now and have been in the industry for only four years. I have never been told to not tell a customer what a heat pump is or how they work. This is not a secret. They are great systems. Sounds like it's just bad companies or a bad sales man that actually picks the equipment to be installed. A good sales man will inspect the duct system when sizing equipment. Nothing should be assumed that anything is okay and we (me at least) were taught this in the Manual J class. Not every Tech knows how to do these calculations and its not their fault; it is the companies fault for not providing a qualified person to take the time and effort to do it in the first place. A lot of companies just tell their Techs to (just make it work or just sell this or that rather than fixing the root problem). You need to find a good company and do some research as they are out there. In south FL, most homes down here have undersized duck work. Why? No idea but we all know about it and yes it causes problems to the whole system. But it is slowly getting fixed with new construction. It is very expensive to replace an existing duct system and the vast majority of people cant afford it. Duct sizing is just as important as finding the right tonnage of a AC system. A senior tech once told me "AC is going to become a commodity for the rich" and I truly believe that.
In my townhouse there's a boiler for heat and hot water, a heat exchanger in air handler to transfer that heat to the forced air system, and an AC unit. It would be straightforward to simply replace the current AC unit with a heat pump (and that's my plan). With the boiler still online there's no downside to having the heat-pump a bit on the small side. Further, in my particular system the evaporator/condenser is before the heat exchanger. This means that you could conceivably run heat from both a heat pump and the boiler simultaneously, allowing the boiler to be down-sized as well. My system here in Toronto was more reasonably sized than yours with the heat exchanger rated to 40k BTU and a 1.5 ton AC unit.
Hey bud, we have the same issue over here in the UK. My house which is less than 5 years old came with a gas boiler (furnace to you guys) and we didn't get the option for a heat pump even though we bought the house before it was built. That aside, I have reduced my boilers temperature (actually on the boiler) down to 38°c which is more than enough to heat the entire house with radiators to 21°c. The manufacturers recommend 60°c which is crazy as it is a condensing boiler that reclaims lost heat from the condensation created when it's on. The lower the temperature, the more condensation, the more heat is reclaimed, the less gas and the more economic it is to run.
A boiler is a boiler here as well. A furnace, in our parlance, doesn't boil anything. It typically heats air with natural gas burners through a heat exchanger, and then that heated air gets forced through air ducts to the entire house. Unless you call such a system a "boiler," which would be wildly inaccurate in any country.
@joesterling4299 oooh, I never knew that. I actually thought that gas boilers and furnaces were the same thing except in the US they heated the air because you all use air-conditioning too, and it just made more sense than installing radiators and ducting for air-conditioning as well. We simply don't have furnaces (at least not in houses) over here.
@somethingfunny6867 I have set a "fall back" temperature on the thermostats to 16°c although it's never dropped that cold. Even if I finish work early and check the temperature, it's no lower than 17.5. I'm guessing my house is well insulated. There's a channel called heat geeks. They mainly focus on heat pumps these days, but older videos focus on gas boilers and setting it up correctly. I was thinking of buying weather compensation, but before investing in getting it installed, I tried lowering the boilers temperature (which is what weather compensation does depending on the outside temperature) and found that 38°c seems ideal. It will be slower to get to 21°c than having the boiler set to 60°c or more, but it also heats up more slowly, putting less strain on the system, and it doesn't over shoot the target temperature.
You can get more geeky by adjusting the flow rate to each radiator, but that is something I give up as a bad job. I have all my radiators fully open, and although you think I will be heating rooms I don't use wasting energy, the heat from all the radiators goes into heating the entire house. If you turn off a radiator to 1 room, the other radiators actually need to work harder to heat the rest of the house up as the heat will transfer into the colder room. It's all about energy states and equilibrium. You might as well have all radiators and rooms at the same temperature since it gives you more internal thermal mass to keep the house warmer for longer.
funny thing, not really related to the content of the video. I saw the notification for this video on my phone and saw the words, "condensed version" but when I got on my computer and logged into youtube, it recommended the full version. thinking I was watching the condensed version, I was.... a tad worried that the condensed version was an hour long. So thank you for linking to the condensed one in your full length video.
I used to live in a middle apartment with people above, below, and on 2 of 4 sides of me. Only 1 small and one long outside wall. I NEVER turned on the heat, even in the dead of winter and the temperature was fine. Didn't save me any money, though, because the whole building's electric bill was split evenly. 😂 Now I have an approx 1400 sq ft detached house, built in the early '80s, and our 24k BTU heat pump seems to work very well except for those few days in the dead of winter when it is really REALLY cold. And on those days my heated blanket is a great friend. ☺️
14:00 other method : during an off we, read your meter when you leave, and come back, let your heater at 20C, and time how long you were away. The test must include at least one night, possibly 2. Check the average external temp over the period. Now you can calculate, for a given delta temp ( internal - external ), the energy used over a given time . That gives you the thermal resistance of your house. Your fridge was working ... But was contributing to heating so does not matter.
One other way you can test if your house is ready for a heat pump, provided that you’re able to change the temperature of the heating medium (water through radiators or air through ducts): lower the temperature and for shits and giggles see how low you can go while maintaining comfort. I’ve been able to lower mine from the default 70 Celsius down to 45 Celsius. And now that I have underfloor heating I managed to make do with 35 C.
This is a good test for hot water systems (and also increases boiler efficiency) but it doesn't work for forced air furnaces. Furnaces output a fixed amount of heat regardless of the output temperature.
The most realistic reason as to why your heating is oversized is because the airflow needs to match the cooling coil and to get that airflow, they needed a larger furnace. It happens all the time. Gas is almost always oversized for this reason. Installing a larger furnace "to be safe" is against the energy code. Also, nobody designs systems for the lowest possible ambient temperature. They use ASHRAE climate data. For Chicago, I think it states around 0 degrees F. That's the 99% winter value.
I use a heat pump (in Florida) and its so nice. I also have an HVAC guy thats honest and downsized my unit (saved me a few Gs) and it cools and heats my house just the same as the old unit but also uses about $30 less of electricity in the hot months.
hi, i'm an hvac technician. holy crap the contractor really goofed, they obviously did not do the calculation at all. ok so info dump time: the rule of thumb for gas furnaces vs a/c is about 2x the btus of the a/c; heat pumps are also sized this way, in that the electric heat should roughly match the btu output of the heat pump (1.5 ton generally gets 5kw, 2 ton generally gets 5-7.5kw, 2.5 ton generally gets 7.5 kw, 3 ton generally gets 7.5-10kw, etc). this is done to ensure that the furnace can still keep the home warm in an absolute worst case scenario, and it also assumes that the home was constructed >20 years ago, which means the insulation is likely not very good compared to what's present. this INCLUDES THE DUCTWORK! old ductwork often has poor insulation too, which leads to losses that must be accounted for in order for the furthest reaches of the home to still receive heat, of course at the cost of making rooms with shorter ductwork warmer. USUALLY, an experienced salesman does the manual-J calculation on their own based on the materials found in the house. good salesmen will go into basements, crawlspaces & attics to see how the house is constructed, look at the size and number of rooms, and perform their calculation based on that rather than just trusting whatever was there. HOWEVER, you sometimes see inexperienced (or lazy) salesmen going solely off of square footage and not really taking anything else into account. while it's generally okay to undersize an a/c slightly for better dehumidification (e.g. in my area where it's quite humid during the summer), you absolutely do not want to undersize a furnace because that could actually have collateral damage if pipes freeze & water damage results from a furnace not equipped to handle very cold temperatures, so often times without a second thought, the salesman will just oversize it to be safe. as you can imagine, this works most of the time, but sometimes does not. i've seen the results firsthand from our competitors, the usual symptom is that the furnace will overheat & trip its high limit switch (located in the heat exchanger, generally rated around 130-180 degrees fahrenheit with ~30-50 degree reset differential), even during normal operation and with a relatively normal input temperature measured around 70-75. technically, you can increase the speed of the blower to compensate and that will work, but if you go too high then you'll get noise complaints from the rushing air over the return & even registers. there are even some new houses i saw where a master bedroom + bathroom had a staggering 7 registers in total, of which 4 were in the bathroom alone, and the bathroom was not even particularly large. let's also consider the customer: some customers like it very, absurdly warm. older folk prefer hotter temperatures, it's very commonplace for them to set their thermostats between 75 and 81 degrees year round; if properly designed just to meet the requirement ("enough"), their a/c will barely run resulting in high humidity, and their furnace will work like hell to keep up. truthfully the correct solution is to oversize but to do so with a system capable of multiple stages or tell the customer "tough luck", but the same people who want high temperatures year-round also generally don't want to pay for the more expensive dual-stage system. hell, sometimes dual-stage systems don't work properly because there are physically not enough wires in the wall to accommodate it (the control boards often have dip-switches to set an automatic timer but for hopefully obvious reasons this is not ideal), and if so, less-than-optimal and generally more costly solutions will be presented that will get the company trying to sell the equipment dismissed, even if they're correct (e.g. communicating thermostat, wireless thermostat, or running new/more wires in the wall - not always an option if the home is old enough). people are not often smart enough to understand these concepts, so to appease those people & avoid receiving complaints down the road because their properly designed system can't meet the absurd requirements of the homeowner... they get oversized. as a literal industry professional, i assure you it's very frustrating to see, because it's literally our job to do this correctly, and when someone messes it up, it makes the whole industry look incompetent. now, let's talk about that new-fangled heat pump technology. the high efficiency one. the *cost* of those systems is actually absurd, it's not that commonplace for the contractor to just have an absurd price because they want to make more money, it's often because those systems are legitimately that much more expensive & may have extra setup time involved compared to a traditional/bog-standard system. those newer technologies usually make use of more expensive & involved circuitry; think of each piece of equipment needing to have at least one dedicated control board just to communicate with the rest of the equipment on the network, and to add insult to injury, the heat pump may have a slew of other control boards managing different things. fun fact! heat pumps have two metering devices, one is located on the indoor coil and the other is on the outdoor coil. this is gonna get long so bear with me: in cooling mode, the indoor coil's where the metering happens, and in heating mode, the outdoor coil's where the metering happens. unlike the days of old where a standard thermostatic metering device can be used, to get those high efficiency numbers, these metering devices are almost always electronic stepper motors that require not only a drive circuit BUT must also communicate on that same bus that everything else does & be capable of reporting errors. these systems also have a few more thermistors than normal heat pumps, which might not even have a single thermistor depending on how cheap the design is - the cheapest heat pump design i know if is goodman, which has just a defrost board & it uses a snap-disk outdoor coil temperature sensor rated for a specific temperature, and if the defrost timer expires while this snap disk is closed, then a defrost engages. that's *it*. the new systems have an ambient temperature thermistor, coil thermistor, compressor dome thermistor, and sometimes even have an extra thermistor measuring the temperature of the other end of the outdoor coil to check the deltaT across it & calculate how much heat is actually being dissipated. same thing for the indoor coil by the way. the very same system will also often have a different kind of pressure limit switch for both the high & low side, which is to say that it's an actual pressure sensor that reads back a resistance representing a pressure, which is again more costly & requires a control board to interpret. most systems have the same style of "snap disk" behavior in their pressure switches, but these actually have a processor on-board that has to use the pre-set formulas & data on-board programmed for the specific kind of refrigerant being used to determine how to meet the demand & simultaneously diagnose problems so that they can report the errors to the homeowner (and eventually the contractor). these systems also have what's called a VFD or variable-frequency drive, which is an absolutely massive variable-speed 3-phase motor driver that can handle the power draw of the compressor while also varying its exact speed to meet the calculated demand. these boards are ludicrously expensive (as in, if it fails, your contractor has to call that manufacturer's tech support to get RMA approval kind of expensive) and on their own drive the cost up significantly. on top of all of this is the thermostat, which itself has the responsibility of calculating the load value that gets read by all other parts of the system to determine how much of a thermal load is on the house right now & make the rest of the system react accordingly. plus it may want a network connection to download firmware updates over wi-fi for the rest of the system so that you don't need to call a professional over to have him sit there awkwardly with a thumb drive on a dongle to force firmware updates manually. so, YES, heat pumps are awesome and CAN be used in cold climates! there are a number of manufacturers who have been rolling them out already, but nobody wants to pay $20k for the whole-home system that costs the contractor upwards of $14k in just equipment (not counting installation labor, materials & sufficient profit required to keep that office running & its employees paid) that will actually do it when the next best offer is a gas/ac combo for about half the price that will in practice heat their home just fine. seriously, go look at the cost of the 20+ seer split heat pumps, wholesale cost for goodman (again one of the cheapest brands with a track record for premature failure) is around $9k right now and that doesn't include shipping or professional installation, the heat pump alone COSTS around $6k-$7k though that will of course vary with size, your home is efficient enough to only really need a 2 ton heat pump but many homes are larger & also not townhomes so they will require much more heating (and cooling). edit: grammar
I just went on the carriers website and they make the following statement. “Typical residential gas furnaces will be available in various sizes between 44,000 BTU/h and up to 120,000 BTU/h.” It’s possible that the high-efficiency furnaces may not come in sizes smaller than 60,000 BTUs. So you may have gotten the smallest furnace that you can get. It might be a good idea to talk to someone in the furnace manufacturing business to find out there take on this.
Good points. My 1200 sq.ft. house, in northern CA. had a 100,000 BTU/hr. furnace installed back in the '70s. I made a video about that furnace a few years back titled: "Getting the Old Fraser Johnston Gas Furnace Running" On-line calculators estimate a 36,000 BTU/hr. rating would be sufficient. I suspect even 20,000 BTU/hr. or a 2 ton heat pump would be more than adequate. I don't use the furnace, instead heating the house with solar hot air with backup from a fireplace insert.
I keep my thermostat set to 15 C (~60 F) and use a portable heat pump just to heat my office during the day. The usual inefficiencies of portable systems barely matter when moving heat within a closed system, and heat pumps are most efficient across small temperature gradients, so it’s 2x super effective. It’s basically using the same principle as multi-apartment systems discussed in the follow up video. Technically my heater needs to work a bit harder to stay above 15 than if I was on vacation, but during the day just passive heat usually will get it close, and by now (March) it reads 16-17 before I even touch the thermostat in the morning.
Speaking as a (now retired) 38 year engineer - electrical rather than HVAC but the idea is the same. The principle often used is: if you oversize there might be some grumbling about price. If you undersize, lawyers get involved and that is a bad thing for the supplier and designer. Your point is very valid, we should design closer to actual requirements, there just is a tremendous aversion to being sued.
There's an HVAC guy in Lansing Michigan (All Star Mechanical) who has had a couple rants about this. Apparently his small company is the largest installer of 40,000 BTU furnaces (the smallest Trane makes) in Michigan. Trane sold 83 40k units in Michigan last year, this guys small shop bought 37 of them. In the last year Trane sold 390 80k BTU furnaces. This guy bought one of them.
I would really appreciate you used the same units for thermal power. You've been alternating between BTU/h to W to Tons as if everyone knew the conversion factors. I'd say you stick the audio to one unit only and put the converted units on the screen for whoever cares.
Also in Chicago (Oak Park). Just put in a solar energy system and looking to completely get rid of gas. This really made me feel better about replacing our 20 year old oversized furnace with a heat pump like I have been planning!
Years ago, I bought one of the first high efficiency furnaces. They only made on size (75000 BTUs) which was way too big for my house. The installer said they would put in a restrictor plate to bring the furnace down to 35000 BTU. You might want to check and see if they make a restrictor plate for your furnace to bring it down to 20000-25000 range.
A oversized gas furnace can have its primary heat exchanger crack from its short cycling like mine did. I went from a 75,000 btu furnace to a 45,000 btu model which is more inline for my sometimes very cold NW Wisconsin home. I’ve seen it get down to -38f a few times up here.
I learned so much when replacing my heat and AC units. We have an efficiently sized unit for a 3600 sq foot house and when first installed seems too “weak” for the house when you’re used to typical air blasting from the vents. My dads furnace is so oversized that when the heat turns on, loose papers will fly off the coffee table Efficiently sized units should run longer with fewer total on/off cycles - especially when running the AC as it provides not only cooling but dehumidification
In my previous home, we had a 40kW heater running on diesel. We replaced it with an 8kW pellet burner. Saved us lots of money, was much more quiet and easier to run. And we were never cold. If we'd have to do the same today, we would have gone for a heat pump in stead of course.
I used to work with people who sold heating and plumbing units. The manager would just ask "Whats the square footage, what's in there now, how many floors", do four lines of napkin math, and point them at a unit. They only ever downsized if the customer stressed "It's *brand new* construction."
I just went through this to take advantage of the recent Canadian rebates for heatpump installs. I had a ~75,000 BTU furnace and a 3 ton AC. It was replaced with a 60,000BTU gas furnace and a 2ton heat-pump. It's all setup so the smart thermostat uses the furnace when the outside temp is below a threshold and the interior temperature difference is too big and otherwise, the heatpump operates. By comparison, my house is two stories + basement and about 1600sqft. Now the issue we have is that the smart thermostat wants to inform me when the furnace runs for too long.
My home has an old 1960's boiler system. Those in energy efficiency is the next step down from heat pumps. But the cost of conversion from a boiler to a heatpump is cost prohibitive as would need ducts run, new vents as well as removing all the pipes and radiators.
It barely got under 32*f here a few times this winter. My Gas Furnace is from 1975, I'm scared to run it, its a 80,000 BTU unit for a 1400SF house... it heats me fast. But power is cheap for me (9c/kwh at night) so I plugged in a space heater, set it on level 1 (600W) in october. I am here in november, and my main gas heater has only clicked on a few times all winter. IMHO amazed a single space heater kept me warm all winter.
I noticed my 2-stage gas boiler was almost only running in the full-output stage for shorter intervals and then shutting down completely until the system temp dropped enough to trigger the high stage again. I did an experiment this winter by just disconnecting the switch that activates the second stage. It maintained temperature in my house perfectly fine at one third of its rated output of 95,000 BTU. I did reconnect the second stage once when we were coming back from a vacation during which the heat was set about 15 degrees lower that we normally keep it. But that could have been avoided if we had a smart thermostat that would have let us turn the heat back up a day or so before getting back. I’m sure an hvac technician would see that my current unit is rated for 95K BTU and try to replace it with a similarly rated unit.
I work with heat pumps for Massachusetts' energy efficiency program and I wanted to reply to something you pointed out, using existing ductwork for heat pump systems. It is very rare that old houses (i live in the north east, so most of our houses) have ductwork that be utilized by a central heat pump. According to the policies our company uses, each floor needs to have a return duct (which disqualifies most 2 story houses) and the ductwork often just isnt large enough even if they do have a return duct. I dont need to know the heating load to run this calculation. Any home we can't fit central heat pumps in we pivot to ductless mini splits. As far as sizing heat pumps, it is slightly more complicated than you portray but you are almost right on the money for the sizing range. The thing to keep in mind for DMS is that the snallest head you can get is usually 7,000 BTUs, and the most heads you can get on a compressor is usually 4. This means you often end up oversizing the head in one room to cover the heating load of an adjacent room which is too small, and often means oversizing more than just the sum of those two rooms to make sure the heat properly spreads, especially in older homes which trend to having more but smaller rooms with less continuous airflow between them. The other thing to keep in mind is that heatpumps really shine when they are holding a home at a continuous temperature, meaning that the more insulated your home the more you will benefit from heat pumps rather than a one stage system. Almost every state has an energy efficiency program offering MASSIVE subsidies for insulation work, my state targets a 1 year ROI on any money put into insualting a home, so if youre asked to oay $2k for the insulation work thats also likely what they expect you will save that year. Everybody should be having these assessments done, they are free in most states.
Oversized everything is a big problem, Alec! Thanks for focusing on the HVAC! Over sizing of heating equipment is rampant My only issue with heat pumps is an issue with forced air heating in general: it never addresses radiant heat and mean radiant temperatures of exterior walls. For one particular cool spot I use a mere 100w ceramic brooder lamp and the comfort level vastly improves with little change in air temperature. But that’s a subject for another day
My heat pump is actually a bit undersized, it starts needing help around -15ºC. I ended up getting a 15KW backup heater on the new furnace box when I got rid of the old oil furnace, which can push out 50k BTU... in an 850sqft row home lol. When I get a new one in 20 years, I guess I'll go for fewer kW, though I do like the hot hair dryer effect when it does kick on when it's cold outside.
We have a 28kW combi boiler which is way oversized for heating. From what I can tell, on the coldest days we have, I use about 120kWh gas. Optimistically at 80% efficiency, that's 96kWh heat, or 4kW running continuously. Replacing that with a 5kW heat pump and hot water tank soon hopefully
if you want to cut down on the capacity of the furnace, just plug the outer burners on the furnace. all you have to do is pull the burners out and take out the orifices on the manifold( screwed in/ pipe thread) and install plugs ,and reinstall the burners. we did that on furnaces that had bad heat exchangers, so the customer could at least operate the furnace until the weather got warmer, and give time to get a replacement furnace ordered, and installed. the outer burners being shut down will not cause problems with the hot surface igniter, flame sensor or the flame runner. .the regulator in the gas valve will automatically adjust the gas pressure to the manifold. you got a furnace that is the smallest unit made, and is still too big, all I can say is "OH WELL "at least it is not the other way around where it is under rated.!!!! I would not remove the furnace, as it would make for a nice back up heating system( second stage), incase the heat pump would fall on its face
@technologyconnections Great video! We have installed an inverter heat pump to replace an air conditioner at my parents' home, and are about to replace a 44 year-old 5 SEER air conditioner at my Grandparents' home this spring with a 16-20 seer heat pump. Since both systems use backup gas furnaces, the only thing we have to worry about is replacing the unit, and running an additional thermostat wire with a "steal a wire" system.
The reason you still want it about 2 times the size is so you can heat it from cold in a reasonable timespan. If you have just enough, and then get home and want to up the temp by 30, you would be waiting many many hours if it only has "just enough"
11:08 Missed opportunity to say miles instead of kWh when describing the total kWh consumption of heating your home in the test. Obviously this is a real strech of units, but I'm people say "we dont have enough capacity for everyone to have electric cars" but easily have 110kWh to heat with resistive heat. Thats enough juice to drive 3-400 miles. Great video as always!
Awesome well thought out and made video! One thought - how much of your btu load is really attributed to your design temperature? For example, if the next owner of your home wants a set point much warmer, say 78 or even higher, and is willing to pay for it of course, what btu is needed for that?
So glad for the shortform of this longform vid as i always love your vids but my ADHD can make it harder to watch when theyre near an hr long or more Thing is, ill probs end up watchin the longform later, but havin watched the shortform version will make it easier to keep focus xD I find this same effect with watchin movies, if i watch an analysis of a movie first; its easier for me to focus when watchin the movie, and still enjoyable even havin been spoilered
Appreciated the information in this series and character of explanation. I am one of those guys that like accuracy rather than expedience or cost so do appreciate the detail in the explanation. On another note, have you ever done anything on low head (less than 25 feet) hydro generators?
I had to get 22 estimates to replace my oil furnace with a heat pump because all but two of the estimates were predatory, in exactly the way you describe. They tried to sell me heat pumps that were 3x bigger than I needed PLUS a gas furnance to supplement it! Estimates were: 1 @ $12,000, 1 @ $15,000, 17 @ $22,000-28,000, and 1 @ $42,000 (this snake said my house needed 2 6-ton heat pumps). Also, the heat pump I got ($12,00 estimate) is waaaay more energy efficient than the ones quoted to me that were 3x the size I need. And, just like you say, the oversize units would have required me to replace my electric panel. Just like you describe, my central duct system doesn't have the capacity to handle the giant heat pumps they were trying to sell me, but its the right capacity for the appropriately sized system I bought. I thought I was going crazy when I was getting all of these estimates, so I called the state Department of Environmental Quality to ask what capacity heat pump I needed for my home and they confirmed these $20k+ estimates were insane. They were totally clueless that companies are giving estimates like this. I also used the J Manual calculator and it confirmed the size heat pump I need. When I said no to these wild estimates, and expressed disappointment that the units they were trying to sell me had such low energy efficiency ratings, then they tried to sell me ductless mini splits, even though I have a central duct system and mini splits would do violence to the architecture of my 1890 Craftsman home. I also have a bee in my bonnet that they all told me I had to have heat strips. I looked into heat strips. They are the energy equivalent of using space heaters in every single room in my house, which is wildly energy ineffecient. I said no to heat strips and on the 0-2 days a year the weather is much colder than normal for my climate, I use a space heater in each of the 2-3 rooms we actually use at the same time.
I have the opposite issue. When heating and air was installed in my house they put in a unit that was supposed to be capable of heating the house. They did not consider that the house is 80 years old, lacks insulation, has original windows and has gaps around doorways and in the floor boards. When it gets below freezing (pretty much the entire winter, 3 months or so) the furnace cannot keep up and it runs constantly and does not get the house warm enough. Yay for space heaters and electric blankets. Also same goes for AC it’s 85 in the house all summer long with the AC set at 72 and it runs constantly but is still so hot.
Been watching your videos for years and never realized how close I lived to you, haha. I wonder if you ever attend any local tech related conventions such as VCFMW, would be fun to run into you if so, lol
A couple of factors you are forgetting. 1. If your neighbors house is warmer than yours, you will be stealing heat through the walls. So if you have an elderly neighbor that likes the heat cranked your going to need less btu's to heat your place but if one moves in that likes it colder they will be stealing btu's from your unit. 2. Most places are designed that you can move a couple of degrees aka gain heat which is more than btu's needed than to just maintain temp. This is done for power outages or because people keep their house much colder when they are not home.
![HVAC professionals aren't sizing equipment appropriately [condensed version]](/img/logo.svg){kind=logo}
