How to adjust airflow and make hvac magic?  

Looks nice on a, from what I can tell, a fairly new house and duct system. What about a 30-year-old one?

try insulating the supply. No radius on the supply plenum elbow??? No turning vains???

I wish we had basement/crawl spaces for ducts to go here in Texas. So much cooling lost with ducts in the attic.

I have a question if you adjust blower speed on a variable speed motor will the blower motor still do the variable speed option?

You need to start carrying a roll of toilet paper around with you on every job that you go to. 'Cause you are the SHHH! (*We're not allowed to say that word!) 😏

Change jumper positions while operating??? Not advisable according to most mfg..... also have to take into consideration humidity in house, wet bulb temperature will determine split....😮

You need to measure return air at filter not use thermostat, those t4 suck for accuracy. If it has an upstairs it is nowhere near the thermostat reading

Check the static pressure bro! This will simplify your process! .5-.7 on most models. Then go level the vents. Nice video.

Most techs or installers don't do this. Also true Delta t requires humidity reading. The higher the humidity the less the split will be. So you might b be at 17° split then when humidty drops it might read 20°. Good work like watching you.

If I only had a dollar for every time I had to adjust air handler fan from it's absolute maximum cfm { usually the factory setting} down to the cfm that matches the size of condensing unit. Well, I guess you could say I've earned thousands of dollars doing exactly that.

This just made me cringe! According to manufacturer's product data, with the initial setting of Cool Tap-A with Adjust Tap-A the air handler will deliver 1600 CFM, which is appropriate for a 4 ton air handler. When you adjusted it to Cool Tap-B, Adjust Tap-A the air handler is now delivering 1400 CFM, or nominal 3.5 ton system airflow. You have reduced total system cooling capacity and changed the balance point of the sensible/latent cooling split. Hopefully in the heat of summer you have not reduced the sensible cooling capacity of the equipment too much that it does not meet the sensible load requirements of the building. Since you have a dual duct psychrometer, you should be measuring the return and supply air enthalpy and delta T to compute total and sensible cooling the equipment is providing and comparing that to published manufacturer's product data.

You may have lower temperature now but are not providing enough airflow to properly cool the space. Adjust the fan speed can cause higher electricity also. I’m more concerned that unit may not be the proper tonnage for the space.

You don't know what you're talking about expert

ok, where would a responsible person start ? obviously by reporting this video for its negligence. but lets assume you did a heat load, somehow i doubt it. these are not the actions of a Real Technician. a real tech would not have started the system before reading the literature, checking the airflow chart, and comparing that to the Heat Load per Man J. a real tech would use that info and have adjusted his fan speed before starting the system. a real tech would know that the noise you complained of will be there during the heating season since you left the Heating Speed in High... can we say Call Back ! but since you are doing the actions of a helper with little knowledge or professionalism, you will probably charge for that call back. and since the High Speed is SOOOO Bad, that system is probably Way Over Over-Sized ! and it appears from the video that your ductwork is Way Under Sized ? was probably based on 300cfm/ton at best ??? maybe not even that ? maybe no one rounded up ? maybe rounded down ? maybe it sounds so bad because it should have had more boots per room to lower the sound ? maybe not a quality install ? a real tech would have installed a Whole House Air Cleaner, after all, it keeps the unit cleaner, protects the equipment, provides cleaner air, and assists in locking in the customer to s Service Contract, especially when you install an odd sized Air Cleaner like some of the Lennox Healthy Climate or Pure-Air systems A Real Tech would not install an Air Handler sitting directly in a Pan with no spacer ... it causes Biologic Growth after it gets flooded. A Real Tech would not install a P-trap facing downhill ... doesn't really trap well in a downhill position, robs trap of its height. but of course a Real Tech would use a manometer on that Condensate Line with system on High Speed to see Exactly how much trap that system requires when it is working hardest, after all, a real Tech knows Condensate is made during cooling Mode, and Defrost is most accurately defined as Cooling plus Auxillary Heat, and during Auxillary Heat, that Blower Speed automatically goes to High Speed. so .... i know what you are thinking, but i have seen it twice in my over 20 years experience as a Real Tech, but it does happen. A Real Tech would know that just because a P-trap was industry Standard 20 years ago, a Quality install requires a J Trap as an Industry Standard, especially when the system performs as yours did on Start Up. A Real Tech would know that after the Indoor Unit is settled, that's when we concentrate on Start up of the Outdoor Unit so ... it appears that you are an adequate installer, maybe forced by bosses to take shortcuts and install so basic and substandard. or maybe you are just cocky and have gone out on your own without actually learning the trade. decent install, left a lot of meat on the bone for the next guy. your competitor will appreciate that as they pick you apart and sell upgrades and improvements. just hope it is far enough out of that 1st year window, and no one has the stomach for litigation. and i really hope there was a heat load done, usually when i see a system that noisy, it was eye balled and over sized. usually leads to litigation. good luck !

You just got yourself a call back because the customer can’t feel the air coming out of the vent.

ALL FINE AND DANDY BUT ID LOVE TO SEE SOME STATIC PSI READINGS

One recommendation: your temp clamp should be placed 6” from test port and on the top of the line set so oils don’t mess with temp

Variable speeds do run at ramming speed if they are changing the temp 5 degrees or so. Then then run slowy. You screwed up the system!

Those Accurite thermometer/hygrometers are okay but you need to test the accuracy of the humidity with a salt test as they are usually off. Get a small container (maybe 2 ounces) and fill it with a damp paste of table salt (not super saturated). Put that in a zip lock freezer bag along with the Accurite and leave it in a room around 70 - 72 degrees for 24 hours. The humidity should be 75%. If not, just mark the device how many points its off either way and you'll have an accurate unit. (The temps are usually all good on these). I have over 15 of these with most of them in coolers used as cigar humidors with several placed around the house and the outdoor shed.

Careful with those cheap temp/hygrometer. I have 3 of them that all read wildly different values sitting next to each other. I have checked their calibration and 1 of 3 was with 3% RH at 50%, others were 7 and 8% off.

Don't own a house, but I am excited about hvac! Great job, will remember the 20 degrees differentiation and that variable fans can run too fast and loud.

That 4 ton was to big for the duct work and probably square footage. If you have to go that low on speed and cant achieve 10-20 superheat. That is probably duct work for a 2.5 ton ac unit.

That's one way to do it, just not the right or most accurate way. You should have measured static pressure and compared to blower performance chart and started by adjusting the blower speed based on static pressure. Also all your ducts shouldn't have the same amount of airflow or velocity either. Depends on the manual J load calculation and the design of the home, and register location...

It's nice when the basement is open and you can access everything but when you have a finished basement and very little access to the ductwork there's little that can be done in way of balancing ductwork and adjusting blower speed. If I went into someone's home and told then, Hey if you let me tear apart your basement ceiling I can optimize and balance your system by changing your ductwork/fan speed for a more efficient system. They would point me to the door and tell me to leave. You also have to consider the customer's budget. It's not cheap to redo all the ductwork in a house and 90% of people will tell you NO. It's a great install and it looks nice. I am concerned when I hear that the units superheat is only at 5 degrees. If your superheat is to low or nonexistent you run the risk of liquid refrigerant coming back to the compressor and causing damage or it washes the oil out of the compressor which would also cause it to burn up and fail. I normally try to set my superheat at 10-15 degrees. I still liked your attention to detail and I hope to learn a couple things from you in the future. Thanks for the content.

Beautiful job, I hate it when the returns are sucking hard, and the vents are roaring. Man! that looks nice.

YORK has some of the worst units none to man 😂😂😂😂😂

Can you show us how to take a static pressure reading and explain to us what it means

Anyone notice that not one of them floor joist have a hangar on it attaching to the beam? Is a nice HVAC system though!!

In college (mid '80s) I got fed up with our apartment's system always blowing like a hurricane. Who thought that made sense? I took off the cover and discovered the fan had 3 speeds, adjustable by putting the wire on a different terminal. Went from max to min, the place was far quieter and cooled at least as well. Today I'm wondering if my upstairs air handler has a similar secret to tell.

What do you do for a single stage? Here on the Gulf Coast, the humidity is so high and temps have been so hot lately.

wish my upstairs room blew 1000 ft/min. its bakin even with the downstairs dampers and thermostat at 70

As a side bonus humidity will be much better controlled.

So the real question to ask is…. What does the thermostat control the temperature of? The answer is… The thermostat! Everything else is an assumption. You have to have air flow to control temperatures in the house!

So 5 degrees superheat is too low. Not enough air over the evaporator will cause liquid refrigerant to wash out your oil in the compressor making it fail. The superheat was moving all over due to the TXV hunting around. In my opinion you just made a perfect expensive early compressor failure. Always keep superheat at 10 to 20 degrees. Your sub cooling looked good at 10 degrees.

I got a similar york unit. Its capable of dehumming also. So far like the unit. Not a fan of the flex in my attic though. I am foamed in the attic. I hate hearing the vents also. Had a tech come by and want to turn up the fans. Need more like you.

One of the most commonly overlooked A/C issues here in Florida is the air distribution. Overuse of flex duct is the devil.

What happened to the super heat when you turned down fan speed? What happen to coil temp? What happen to delta?

You don't adjust airflow to delta T to be 20 degree, you adjust airflow to system manufacturer's requirements, (you design your ducts to that requirements). If everything is done correctly usually you will get delta T of 20 deg or slightly higher. If ducts are done correctly they are not noisy. It is like trying to meet fuel economy standards by driving your car no more then 25 mph. Thanks for posting your video!

You mentioned about having a digital hydrometer and a dehumidifier i have both and not certain if my house has foam insulation or bit because there is spray in insulation in the attic. But what i can say is that the air coming out of my registers are roughly 70% humidity when the ac is running. I have a track home in se Texas built 2018. Any idea wth is going on? My free standing dehumidifier with built in pump just cannot keep up.

Something to think about. 12 to 16 degrees superheat. Do u follow the charge chart or apply the 12 to 16 degrees principle?

My Honeywell pro series & My temperature is not reading room temperature going high temperature by itself & it takes forever my unit or or coil my coil is 20 years old already one of the rooms not blowing enough cold air only things only night time around 10 pm clock it does go down nighttime only Andy daytime my temperature goes up high temperature what to do I think it needs a tune-up check up I hope it's not that was it something else wrong with it AC I like your videos I'm learning how to do it @TaddyDigest

HEY, I BECAME AV MEMBER, BUT I STILL CANT WATCH THE MEMBERS ONLY VIDEOS.

Over time k-type connecters where it plugs into your meter. Those flat blade types. They usually don't have a good strain relief and you can take it apart. Cut back to fresh wire and re-attached to the two screw heads. I see those ones are not-re-buildable. Get generic k-type ends that are field wire capable.

Good content, bad photography. Stand still ! I was getting seasick during summation.

I have a Amana AHVE36CP1400AA Inverted air handler that’s very loud. Can fan speed be lowered on it like in your video?

What can you do in a 2 levelhouse with Terrible duct work to up stairs?

if i were to hire an alleged HVAC certified tech to do what you show in this video, what questions should i ask of the tech company before hiring?

I just had my 5 ton American standard 2002 serviced by my cousin. I called an air conditioning company who informed me that I have R 22. Which is so expensive at $275 a pound, i might be better of changing my units (i have 2.5 magic aire in the basement). So I went online and bought 30 pounds of R22 for $924 for just in case. My cousin found the leak slow leak in the attic. Added 10 pounds of R22. Fixed the motor in the basement unit. Spent 7 hours doing the job and charged me $500. My units are running like brand new. Because I gutted my house before I bought it and had both units put in. 20 years and counting very little problems so why change them. Now if I'd got the same job done by the original company I'd would of spent $2700 just on Freon R22. I doubt he'd do such a fantastic job as my cousin. Because he took his time to figure out what was wrong with my unit which was iceing up outside and not cooling the house once it got above 85 outside

Yorks are terrible, hopefully you don’t start to get sweating now.

You need to add joist hangers where joist meet header beam.

lol, 3-5* superheat, What happens when the filter gets dirty?

Charge it up a bit . 98 red side, 45 / 50 Blue side

Well factory charge is 15ft on that York. Then there is a chart to add after that. Off top of my head its .6 oz per ft after. I would add extra charge befprw opening valves. Dip switches should have been set before turning on power. Rwmember long flex lines past 5' add static and drop cfm/pascal. When in doubt pipe it out. Flex should ONLY be use to minimize vibration.

What would you recommend for my setup? We have a 3 floor townhouse. No basement, first floor is on concrete. Our unit, however, is up on the third floor. Its a reversed system. Upstairs is always dying in the summer and comfortable in the winter while downstairs is cold in the winter and average in the summer.

Am I understanding this correctly? No matter the size of the room, the supply vents should blow the same amount of CFM? If so, what should that be?

What about the filter? Merv on my in laws is like 1 and getting a lot of mud in evaporator drain lines now getting freeze ups . I’m trying to tell him to get something better but he’s worried about losing air flow? I have a 4 inch merv 11 on a standard blower and works great. I need one of those airflow meters!

Looks like a poor commissioning job. Its amazing, if people actually checked and adjusted airflows to correct sizes things work trouble free.

So the thermometer/hygrometer determines if there's too much air or too little cfms?

The delta T reading is meaningless for performance wo a humidity reading

Well this is the thing of slowing down the fan… it will cause air unit to freeze up because there’s not enough airflow esp if you have spray foam insulation in the walls and attic.. and this is the last thing you wanna do because moisture from a frozen set of coils will cause water condensation and that leads to MOLD.. need you to do more research mister..

Great video, unfortunately, from house owning experience, not all duct system is done well. Current house on a dual zone system, and struggled for a year to get it better, and it will never be correct, unless I want to rip apart a finished basement and fix all the ducting. But I have learned a ton the last 4 years becaue of this house

I’m not a technician just a home owner. Had new system installed (Canada). 1.5 ton AC with 2 tone A coil. They didn’t set my fan speed but I do know how to adjust the taps myself. Currently it’s on 796 cfm should I knock this down to 596. The old system that died was a 2 ton. They said I was over sized. 1300 sqft house. I did try it briefly but I only saw at the register about a 1 degree drop. So at the lower speed I get 53.7 Is 200 cfm really worth the reduction. I’m seeing the upper floors warmer a tad dripping down the cfm

I do lots of auto ac repairs, replaced an evaporator in my truck recently, thinking of doing this as a job :lol: It is similar. There is no subcool on a truck though :lol:. Once the truck moves everything changes. It is charged strictly by weight.

Is there such a thing as the return elbow to the furnace as too big ? Mine is 10" x 25" coming down to the elbow.

In Louisiana it hot heat wave

The 30% decrease in air flow with the 2 degree change doesn't seem like a "win" to me. If it would be 100 out like it is here that system would never keep up. Why do you feel this is better?

260 Psi high temperature pressure gauge (red). 20 cell per division.

I love my fast hard blowing ac.. my house stays freezing cold..

Hi Taddy, Love watching your videos! You are very thorough with your work. I have a question regarding air flow. I noticed the return in my second floor is not pulling any air in. When I block the return in the first floor the upstairs return then starts pulling air in. Do you have any ideas on what the issue(s) could be?

Why is lower fan speed better?

So you made it less efficient by having less air flow. People pay for you to make their system worse?

Maybe I just missed it, but I don't think you explained why this improves things or how it works. I get that the lower blower pressure is quieter, and you said that it also improves the dehumidifying effect, both of which are nice but is there some significant improvement of cooling effect that results from lowering the blower pressure? You showed that the air coming out is cooler, but of course it's both the volume of air as well as the temperature difference that determine the total amount of cooling effect. Is there some sort of optimum tradeoff between CFM and temperature? As for how it works, my guess is that because the air is moving through the plenum more slowly, it has more time to get cooled by the evaporator coil. And, of course, the colder the air is, the more humidity drops out. Is that the whole explanation or is there more to it than that?

I wish I had someone to come to Chester County and check my like that I can trust.

Adding a dehumidifier is just wringing out more moisture right?

Tad i would like to know if you have different size registers in the should they all still blow the same or should different sizes blow different speeds ? Just curious

Incorrect on airflow. Different size flex produce different cfm/pascal

Thank you for the tip you are the best

I have had this issue for a couple of years since I bought the home. All my rooms in the back of a single story family house that’s not even 1500 sqft don’t get as much airflow as the living room and kitchen. The middle room of the three in the back hardly gets any airflow out of the vent. How can I get that fixed, my child is in that room and I live in Texas so it’s hot in his room in the summer and cold in the winter ?

How do I find someone in my area who will perform a a detailed test like this?

Most HVAC people I've seen, install, turn on and you never see them again. Never knew these details before. Want to install a system in California?!

the return in our home is the interior of a framed out sheetrock wall its like a 2.5x2.5 chute up into the attic and the top of the shoot is a duct box. There is the backside of drywall, studs, and the concrete slab exposed in this space. Is this correct?

Nice looking job!!!! Getting that evapor coil as cold as possible slowing dowing the fan speed, Question what was the total static pressure on the duct system? looked good no vent ducts on the end looked well balanced, keep up the great work bro 👏

I have a new unit but some of the rooms upstairs are not cold?

Is 700 the best target airflow for pretty much all systems or just this house in particular? Also, I know that if a system doesn't have enough airflow then it can freeze up, so does lowering the fan speed not cause future problems?

I moved into a condo where the air is not balanced in the upper level. It’s about 10° higher on a hot day. I’ve determined the problem is the air return. It just does not pull hard enough to return air from the upper level, but does fine at the main level, there’s about 40 feet of run for the returns in the upper level. Is there a solution to this?

How do I adjust my fan speed?

I had same problem when I moved into my new mobile home. The system was not commissioned. Installers left fan setting on highest setting and I had great delta T but humidity was off the chart. Very uncomfortable. Changed fan settings to lowest speed and now it’s very comfortable.

Was gonna say looks good if it’s 75 degrees but you beat me to it

Is there tornados by you Ted?

5 degrees superheat bro. That’s major liquid flood back. That compressor ain’t gonna last long lol.

Getting 12-16 degrees temp differential at the vents isn’t bad. When you’re delta T is too high, not enough air is getting throughout the house due to low fan speed. Good chance the customer will complain the ac won’t keep up on hot days. Still fairly new in the trade so I’m enjoying the educational side of the videos but in the field, this has been my experience.

Excellent...you did a great job....I never ever had an a/c tech do what you did....never ever once was the subcool or superheat checked or balancing the the air flow.

Hello, I have a bi-level home and cooler in the lower half (finished) I have a return vent on the other side of the wall just before my filter, question since my upper level is way warmer, should I close that lower return vent located near the filter ?

I feel so antiquated with my 2004 Trane Heat Pump....everything is so fancy now

Nice good job

1,2 degrees cooler but little air coming out of the vents this may runs longer to cool the house

Need 5000 cfm to 2nd floor and 100 cfm on the 1st floor. Then MAYBE the 2nd floor might actually get cooler. He is fine for a 1 floor house but not a 2 story. Need 25 humidity for summer and 75 humidity for winter lol. Why are there no supply and return vents in the basement?

How does slowing the fan speed down make the air coming out colder?

Your all video knowledgebel nice sir

I live in Florida so I'm interested in your comment we just had all of our events in large intakes and air flows new air docs we still cannot get the house right now below 73° be lower before that it was working fine I have a new thermostat from Honeywell 70 program which I think is 1 of the problems What is the best temperature to come out of the air vents from the ceiling not the intake mine is reading at approximately 58° I think that's too high .. When I read it all the vents somewhere in large most of them were except for the 1 in my room it can't be enlarged they should have put a new vent somewhere else but the location of my old vent is on a main arch beam or near it So we don't get eagle airflow but we have plenty of plenty of plenty of airflow for 11 square ' house actually too much air flow, anyhow that I have most of the ratings or approximately 57-58 1⁄2 ° coming out it seems like it should be coming out colder to keep the house cooler I do believe that our fan up in the attic is turned on high Please advice interested in a lot of comments here I've had 4AC people out and 4 people have told me the same things actually I mean 4 different things everything is running fine there's no problems with my unit there's no problems with anything the TVX was checked everything is fine I think it's just over working Looking forward for all of you have people out there to give me some solid information before I lose my mind Ended up getting 2 window units 1 each so I could sleep at night