Home Pressure Effects of Unbalanced ERV, Ventilating Dehumidifier, or Supply-Only Ventilation
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- เผยแพร่เมื่อ 29 มี.ค. 2023
- Modern ventilation devices have finely tunable airflows- but what does tuning them actually do to your home? Let's dig into the math on unbalanced ventilation with ERVs, ventilating dehumidifiers, and supply-only ventilation.
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Thanks, I am in the middle of a whole-house renovation in Las Vegas. Your information about heat flow, humidity, and pressure really helps on understanding a complex of many factors - instead of just looking at an unbalance system. Thanks again for your deep share and I am starting to see a big picture of how air operates in a home (especially in cold and windy days).
YYYEEEEAAAAHHHH!!!
Some more great content. The topic got me thinking about an engineer friend of mine who 30 years ago built McDs he told me way back then that they spent big $$ on hvac to over pressurize their stores for the sole purpose to keep flies out. So I guess that's why you very rarely see flies in McDs
Haha gross, and good thinking
Your content is so impressive! Do you think HVAC guys should be doing more of this type of stuff or should energy auditing become a whole separate trade?
We would all love it if HVAC techs could get into this- you all get the calls, and you’re in the homes once/twice a year already!
NIce Job Corbin!! Very well explained. I really appreciate you getting this info out as it is much needed.
Thx Kurt :)
Loving your videos. Getting overhelmed trying to do all of this math. My issue is that I live in Michigan, and in the winter, I have cold air coming down my fireplace (with smoke occassionally if there's a fire). I finally realized thru your videos I'm having a negative air pressure situation. Furnace, gas dryer and water heater, bath fan (not used frequently). Bottom line, I need to equalize the pressure, or have some positive. I think I'm back to wanting an ERV. Looking for a product that would automate pressure balance on my existing 1970's furnace colonial house. I actually got AI to provide an answer! Do you have a video already for this? Sure you do... How would I vet a HVAC guy to know they know what they're doing, or do I do this all myself?
You're very impressive! Love your videos and logic.
Chris
Industrial Maintenance Manager here, We run slightly positive at the factory 🏭
Seems like all the reasons we do it apply to the home too
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Great information, very well presented as always. I am currently installing a Sante Fe 120 Ultra dehumidifier on a 120 year old house in New Orleans. The contractor is piping in the outside air through the ventilating dehumidifier. I was wondering if this will add any benefit as I am sure my old house has lots of leakage through doors, some old windows, and even the floor. It will put a higher load on the dehumidifier.
What if you put an ERV unit and duct the fresh air supply to that intake 6” duct on the dehumidifier? Then have 2 separate return systems, one for the dehumidifier and one for the stale air exhaust of the ERV?
I’m building a recording studio so the ducts both supply and returns go through boxes built to diffuse sound transmission yet supply fresh dehumidified air. The hvac will be split units that have silent mode like Mr cool.
Big fan here! I live in an 1100 sq ft brick loft in and old building with smells coming in in Brooklyn, NY. There are smells coming in from below/outside. do you think pressurizing will keep smells from below and outside at bay? Also - do you have any openings sooner than your website? Would love to get on your calendar sooner to help me building my music studio. Thanks for all of your work - as a singer/musician you really guided me to buying my ERV and understanding this process and how it can help my overall health of my voice. Thanks!!
Excellent, Eli! I'll be here. You can use this depress calc to figure out how many CFM you'd need to bring in to pressurize your loft, too. Happy to run that calc in a consult, or you can give it a shot.
@@HomePerformance looking forward to working with you - which email to reach you at for the consult?
You can book directly at: buildingperformanceworkshop.com/video-consulting
I Have Broan B150E75NT AI Series. I'm using the Independent T1 Install Setup. When Exhausting/Supplying from/to more than One Area/Room/Locations, How do you maintain Suction/Supply Air? I Have noticed a Significant drop in Air Suction from Exhaust and Decrease in Supply Air when I "Tee" in to more than One Area. The 6in Ducts drastically drops the air movement after I "Tee" Off into Any Location. How do You Overcome this?
I upsize the duct trunk to 8”, and yes the flow gets cut in half every time you tee, but it all should add up in the end.
We use an always on central bath fan and ventilating dehumidifier, it brings in around 100 cfm. We only slightly are pressurized. I am wondering if it would be better to have motion sensors on the bath fans since the pressurization isnt that high.
I bet your ventilating dehu doesn't bring in outdoor air 24/7, AV- so your pressure would be flip-flopping in that case.
@@HomePerformance It does. We use a humidistat to kick on the compressor when humidity gets over 50% but the fan runs 24/7. Same with the central bath fan. We put in wiring for boost in the bathroom but have never needed it. We did 30 cfm (i like hot showers) in each shower and 20 in toilet rooms. We originally were going to do an ERV but when they did the calcs for the ATL area the kwh saving was not worth it.
Interesting, AV, that’s an unusual setup. Way to think outside the box!
I'm building a 200 sq foot tiny home with an 11.5' ceiling (and loft). I will have an ERV and range hood vent over my cooking area. (If it matters, I plan to get a mini-split for heating/cooling). Is it possible to have too much air exchange? Or can I get a range hood and ERV that have any cfm count? Thanks!
Lawrence Berkeley Nat’l Lab buddy of mine helped me design the one for our 200 sq ft thow, 30 cfm continuous is a good minimum to aim for.
And ps, you need make up air. If you haven’t seen this:
th-cam.com/video/Xy4OvjEd3IE/w-d-xo.html
I have a 1970's home in Minnesota where every "standard" (Not air tight new builds) home has a long 6-8 in flex duct that is hooked up to the side of the home and terminates over by the furnace with a slight bend at the end, dumping warm humid or cold dry air into the basement. I realize that this is the fresh air supply for the home, especially useful if you have old school heat/water gas furnace. Is there a way to allow this air to come into the home, but still be able to filter/control it?
Ohh. I was wondering why I had an extra duct by my MN furnace. I don’t think it’s a needed since they replaced the furnace with 2 pvc pipes for air/exhaust
That's probably not supposed to be ventilation air for the house, Eric, it's likely a misguided attempt to provide combustion intake air for the furnace, I'll bet $100 long distance it's completely unnecessary. As described, it would work only on cold days, when outside air will be sucked in- all summer long, that's bleeding A/C to the outside, and your home gets its supply air from the attic (gross and super hot/humid).
I have an icf home built to passive house standards. I have a .2ach50 my leakage was 90cfm (comes in the electrical panel). We put a venmar x24 hrv. Should it be an erv? I live in Nova Scotia Canada and we are having trouble with humidity. We run a humidifier just to keep the house at 50%. I hope I hear from you.
i would. it will mean your humidifier won't run as much. not sure what your summer is like, if its humid summer you may need a dehumidifier as well. have your mechanicals control your humidity and the erv makes it easier for them to do their job.
Hey PD12, you can probably just order the replacement core as an ERV from Venmar (aka Broan). Yes, that would buffer against dryness just like the HRV buffers against coldness. By the way, 50% RH is a pretty high humidity in winter- might want to try turning down to 30%, makes condensation way less likely.
So what would actually happen if you got 3 pascals off pressure on your home? Would it make it more like a surgical room like you said?
It basically comes down to a fight against the outdoor temperature and wind. Maybe I should make a nerd level 20 vid about the stats on that fight.
Does it make sense to use erv/hrv instead of (or with) bathroom exhaust fans and range hood exhaust?
Mostly looking to condition makeup air for cooking (electric) and showering
Another video coming soon, Andrew, but short answer I'd never use an ERV for make up air- it ceases to be an equalizing ventilator at all.
Just learning all this stuff myself, but range hoods should always be vented directly outside. They could clog an ERV/HRV, plus there will be build up in the pipe.
Truth
I love your Chanel , is there any way I could send you the plans to my home and have you recommend how I should duct it. I’m building a home in Panama , and it’s very difficult finding qualified people to do work like you do. The home will be insulated and pretty much air tight compared to what they build down here . Just need ac , it’s always 26* to 33* all year round. All the contractors here will over size what I need , the house is 2700 sq feet. I will pay for your expertise . Thank you
Hi Giuseppe- yes, I consult on 10 projects per week, here’s where you can book a slot:
buildingperformanceworkshop.com/video-consulting
@@HomePerformance ok great I’m in Canada for a couple of more weeks then back home , I retired in Panama I will definitely book a slot thanks for the quick reply, I’ve been in construction all my life as a paint contractor, but I’ve learned a lot about other trades, and I’m sure I can pull off the duct work for my hvac system as long as I have guidance . Of all the channels I’ve watched your the person I feel that can make a job go smoothly . Thanks
Corbett how Badly can a powered vent gas water heater imbalance a house without make up air?
Depends on how airtight the house is
btw something to watch for with hrv/erv's. i recently found a brand that has EC motors, but it does not have individual controls so you can't put the erv out of balance. or more importantly can't balance the system without using dampers.
What brand, T?
@@HomePerformance i think that was cleanaire nz.
corbett, do you have any info about the story that balanced ventilation isn't worth it until you go air tight enough? the story being there is more ventilation air going through the envelope than whats going through the balanced ventilation system therefore making the balanced ventilation pointless.
Sure, few weeks back: th-cam.com/video/lnOCAPPVT5g/w-d-xo.html
@@HomePerformance i think that one was comparing to bath fans not supply side. if i understand it correctly usa typically uses negative pressure ventilation while here we use positive pressure ventilation.
Air doesn’t hold much thermal mass, AND balanced ventilation is costly to install and maintain, so yes, I’d only want it if I needed it.
so why have balanced ? you can just take sure you don have negative pressures, and don have to worry about commissioning or adjusting....you dont necessarily need positive pressure, you just need to eliminate negative pressure right ?
How do you propose doing that if you use one-way fans in bathrooms and laundry intermittently?
@@HomePerformanceuse an erv in all bathrooms rather than fart fans?
I’ve heard you say a few times that an ERV/HRV unless you have a really tight home. What are the downsides to installing one on an old home?
Downsides: cost, installation complexity, testing, monthly/quarterly maintenance, no benefit of recovery core since air holds very little heat and you’ve got more air leakage than ventilation. Exhaust fans and supply ventilation: low cost, simple design, zero maintenance.
The moment you pointed out that its not about saving money, i decided to watch the whole thing. Every fking daily life scenario, where you eventually google an instruction or tip...its always about saving fucking money, and not actually being factual. I want it proper.
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Some friends and I actually had a discussion about the topic this week. Here is a link to the video…
th-cam.com/users/liveG7PtALUZZRo?feature=share
Nice, Tim
But Corbett shouldnt the goal/inflection point here no NEGATIVE pressure so even a modest 1 pascal gets you past that threshold ?!
The odds that a breeze or stack effect will equalize or overpower your slight pressurization is higher
ERV - This is very bad advice. Too much to list. What I can say is that 1) ERVs require a balanced airflow to maximize the core’s effectiveness 2) Tight homes are not necessarily healthy, loose homes are not necessarily unhealthy 3) Energy efficiency is the enemy of comfort 4) Broan ERVs are sub-optimal for the simple reason that they do not substantiate their core’s latent performance 5) People understand 60, 70, 80 percent of a subject and fill in the rest with a word salad.