I am a new guy to the hvac industry. I appreciate all the time and experience you have placed in your videos. My understanding has grown enormously. With my attitude and help from you and your book , I will accomplish great things. Thank you again for the help
Thank you for the education on home performance. I recently went to a local home expo seeking a company who will test and correct my home. Some companies were scared by the questions I was asking. But I did find one who was very welcoming to my questions. Even asked if I was in the business based on my questions. Thank you so much for helping me find a reputable contractor. Can’t wait for the tv show.
Those dm32 gauges are beautiful things. Internal wall cavity leakage is a massive issue down here in Australia. Air movement through these internal walls, equates to more uninsulated surfaces to contend with on top of your external walls. Very useful video. Thanks.
+Laron Selfridge So glad you found it helpful, Laron! Hope you subscribe and also go back through past videos, there's a lot more where that came from!
Great video. Just had a thought though. When you first start a blower door in the home you should open all interior doors correct? And then one by one check your zonal difference. But shouldn’t you, after each room, open the door ajar as this may lead to subsequent readings as you make your way to each room?
Energy Smart Home Performance You're welcome! I hope Cleveland appreciates all the zonal pressure mastery you're bringing (if they even know what it is)
Home Performance I did some tonight, a 1.5 story master suite over a garage was 20 pascals connected to outdoors (50 base) and the knee wall attic was only 35 pascals connected to outdoors. Yuck! I left my IR at home by accident, but that told me what I wanted to know.
Energy Smart Home Performance Recently had a conversation with a pro from the older generation, Nate, who thinks that the percentage-based interpretation is bunk. I asked: "How would YOU present this data clearly for a homeowner?" He replied: "I don't think we SHOULD be telling homeowners about this stuff." Purists versus populists, my friend.
Hello again Mr. Lunsford. I have been reading your book and working out the exercises. I have reached the chapter on zonal pressure testing. I read it, also followed your youtube videos like this one ( Believe me when I tell you I understand the concept ) But as I am new to blower door testing and other techniques (defining the building envelope) ; one of your questions from the chapter made me think, then ponder, then realize I need a little help. The question asked the following :a blower test kept the home at -50 pa. I test the ventilated attic and get 35pa WRT home. What does this mean? What would I like to see? I feel first that an attic should be sealed. But then I know the ventilation is needed so the roof and interior space can have a stable temp. So testing the attic require that I covered the vents ( like in the duct tightness test ) ? Is this interior attic considered a buffer zone? In fact I don't think I understand what a buffer zone is defined by. Finally what target do you want the attic to be. 0 WRT home means that the attic is an interior space 100%. While 50 pa means 100% outdoor space. What would be best for an attic that's ventilated? I apologize for the long post. You inspire excellence and I promise I tried to figure this out prior to writing you this large post. Thank you again for making me better.
Joseph Quattrocchi You are awesome for asking such a cool question. No worries. You want the attic to show 50 Pa in your scenario, not 35. 35 indicates that there's a definitive connection with the home that you don't want. If the attic is vented to outdoors, then it's a buffer zone- my only point in differentiating those 3 zone types is that you always want either a 0% or 100% connection to outdoors, regardless. Any gray area is an opportunity for improvement. Check out the Hole Size Ratio table in the book in that section- you'll see that if an attic is 37.5, then for each 2 vents between the attic and outdoors, there's one between the attic and the house. PS- you would totally dig the Fall Fast Track, if you want to study with me seriously. Have a great week, and keep the questions coming!
Just found your video and was wondering if you have to have a blower fan running while testing...we work on large buildings +/- 100,00sqft and it would be cool if we could use the manometer without the fan and conclude if there's leakage...
Corbett, catching up on more content today. Couple of questions: 1. Do I understand you correctly that if you are ZP testing, and your pressure pan reading on a supply register is more than 4% of your total pressure, that means that branch is more leaky because it is finding relief to outdoors? If that one is more leaky than others, does that mean the leak is in that branch? If all branches are very leaky, then it could mean a leak in the main trunk? 2. A typical master suite (bedroom, closet, bathroom) may have 4-5 supplies and a return behind the door when you close it off. That's a lot of connection to the rest of the house. Is it possible that a ZP test could show little to no pressure change because of these openings, when it's actually very leaky to outdoors? Would it be better to tape over all supply and returns to rule out duct leakage and connection, then perform ZPT? Great explanation on ZPT by the way. Happy Friday! Thanks.
Hey Tim- yes to #1. And for #2, the thing to remember is that this test is more QUALITATIVE than QUANTITATIVE. Any home’s rooms will probably be ducted similarly, and you use ZPP to prioritize rooms. Keep it simple during testing.
Hey Corbett.. thanks for posting this video and explaining the mechanics of pressure testing with a good sense of humour.. My question to you: if a person is in an older home in a colder area and you provide your service.. they follow your recommendations and as a result, their house is a lot more air tight.. do they now have to consider some sort of fresh air replacement (HRV) equipment? Tnx Richard. Northern Canada
Short answer, YES- in fact, lots of us agree that even leaky homes should have some kind of outdoor air ventilation. What happens when it's mild temps outside and the wind won't blow?
Hello Corbett! Any thoughts on what a window AC unit would do to these numbers? A lot of clients have window AC units in during the summer and it is some times difficult to remove the unit for testing depending on the size. I was wondering if you had any experience with window AC units and how that would effect pressure differences as well as the CFM50 of the whole house in general (having those units in place)? Any feedback is much appreciated! I do a lot of performance testing and always find my way back to your videos when I'm stumped or need a refresher.
Hey Austen, thanks for being a fan, and for your message. In my experience, the units themselves don’t make as much difference as the hack job the ‘installer’ did (wink). I like to take them out for testing, personally, and in fact in energy modeling software you’re encouraged NOT to include them at all, since they’re temporary, and not a part of the home so to speak.
Love the videos, I’m learning tons. With regards to the zonal testing of rooms, would it be better practice to re-open a room door before starting the check on another room? Wouldn’t having multiple doors closed, slowly start to skew the math with the relation to reference?
That question is simple on one hand: you must have the blower door configured to hold at pressure, not speed. If it runs at a constant speed, then the pressure diff will slowly build, yes, due to the shrinking volume. However, you DO want to re-open doors generally to make sure all air pathways point to outside or blower door zones.
Depends on what the goal is. Generally, as-operated is the most meaningful, but if I’m testing an airsealing job, then yes, I block off the mech openings to focus in on what we want to know.
Great stuff Corbett! Was a follower back 10 years ago when the energy code in Illinois brought envelope and duct tightness testing into practice. Moved to Knoxville TN four years ago and building performance is a new and growing field here. You are using Retrotec, I recall in the past you used Minneapolis? What are the pros/cons of each?
Love the box buddy, I have moved up to the TEC pan itself, but I miss the box lol. What did you find out about the ceilings? Im thinking not too too much maybe some air sealing opportunities. Seriously tho, Zonals are usually a higher % in the corners of each home. I also like to do a zonal in the Attic, Basement, or the Garage in the (audit)-pre BD testing. Then use those #'s for air sealing/dense packing purposes. Njoy! MeM
Michael Scibetta You're one of the few- this is one of those tests that everyone says they do, but I find very little evidence to support that. I wish people would ask more questions!
Home Performance Then they are knuckleheads & are missing out. It super awesome when performing Energy Education to our customers,(while running these tests) just to see the look on there faces, (I like to match that with dollar signs-im not gonna lie) This is why I like to provide this service to them.
Corbett, the only problem with this method, is that you can’t quantify the ratio of Connectivity toninside/air leakage to outside, which will manipulate this number. Ducted Heated heating outlets and how they have been commissioned depending on the length of runs...
Home Performance one method I use, is just closing the door slightly, and feeling how much air you can feel coming via the door? Again you would need to tape up the ducted heating outlets though. So that you know the majority of air is coming via the door and not bypassing via a ducted heating system. But I guess it’s the same net effect. 😉
Hmm. Purists vs. populists is one way to look at it. I agree it's not the right approach for every client. Part of our job as consultants is to solve problems. By giving homeowners real metrics of what's wrong with their homes, we cause more pain. More pain means they will spend more money to solve it. More money means better results if the project is designed. Results is our goal as consultants, so testing can help us do that on some fronts. I'm curious how the old pro interprets results, is there a better way? Percentages seem decent to me. Most of what we do is somewhat inexact, I can live with some ambiguity if I can interpret test results.
-A. if one pre tested a register 10% ( 5/50=0.1) B. Duct sealed C. Post tested at 5% (2.5/50=5%) Q. Based on the test data supplied above...Could one assume that leakage was reduced by 50%?)
Hm, interesting q, very complicated answer. For example, if the duct was wide open disconnected in the crawlspace, and the crawlspace showed ZPP of 10%, then the duct pan would too. Then, you could make the duct read a 50% reduction by airsealing the crawl, and not touch the duct at all. It’s complicated.
You forgot that one important factor… The guys doing the blower door tests, are doing all of the blower door test for the GC… They also go to the same bar together ,along with the building inspector… Lol 🙈there goes your building science… Sadly I’ve seen many new homes built in my area where the bonus room is freezing cold in the winter and stinking hot in the summer… Supposedly, they had a blower door test , snd the HVAC system was “ sized correctly”…using a manual J…..🙈… I saw one case where the guy doing the blower door test was paid cash to give it a pass… I wish it were not the case but unfortunately, that’s the reality of the situation in my area. Real estate agents refer to good technicians as… “Deal, killers“… It’s the same with a lot of general contractors, who are unable to build a tight house….the end result will be that the good technicians will be broke, and out of a job…🙈😅
