Episode 3: The Case Against ERVs - Ventilation 2/5
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- čas přidán 12. 03. 2023
- Unless you need Samuel L Jackson to describe how cold your winters are, you don't need an ERV or HRV (energy or heat recovery ventilator).
We'll walk through the case of why we don't like them for most applications.
This is the second episode in the fresh air ventilation series, if you have questions watching one episode, be sure to watch the others.
1. The Ventilation, It's Gone From Suck to Blow! - An overview of the 3 strategies of mechanical ventilation aka fresh air - suck, blow, and suck/blow. Sucking sucks.
2. The Case Against ERVs - These are old thinking and a bad way to spend budget, plus they can contribute to humidity issues. czcams.com/users/liveeLI4D-RzhF0
3. Ventilating Dehumidifiers - Pros and cons of a tool we use a lot. czcams.com/users/livevMIAVGrFB3c
4. Blowing Is Best - Pros and cons of pressurization strategy. Mainly pros. czcams.com/users/liveG7PtALUZZRo
5. Real Magic: Reheat Dehumidification - How to control humidity without a separate dehumidifier. czcams.com/users/liverlHs3gTeb5Y
70 second video on Duct Pressure - bit.ly/DuctPressure
4 minute video on 6 HVAC functions - bit.ly/HVAC6Functions
The first step to leaning HVAC20 is to sign up for the Free Quote training in Kajabi.
Here's the link to free quote onboarding:
nate-adams.mykajabi.com/offer...
Here is the video showing what that step looks like:
• HVAC20 Monday Meeting ... - Zábava
52:07 “We went in there and knocked the fire out of it.” -Reedie Ward. 👌👌 Nailed it!
I always appreciate you doing a deep dive into the numbers great video man!
What surprised you if anything?
Great video!
Are there any ECM bath exhaust fans? (There are....) Run those to get stale air out of house, (typically near a bedroom), while the AHU + makeup air is running. Set or tune the makeup air damper to still keep the house under slightly positive pressure. There, cheap and no ducting beyond the existing AHU.
For a system with minisplits, make something to bring in outside fresh air and mix it with the conditioned air from the minisplit head.
@@DaleKlein in 2 weeks I’ll show tested pressures in homes with pressurization strategies.
Lunos HRV's are popular to avoid ductwork in retrofits. But they are $$$. Are there supply ventilation solutions that avoid ductwork?
Yes, we’ll talk about them in 2 weeks.
Reedie- in the job you describe at about 49:00, did you have the ventilating dehumifier running constantly , within set range of outdoor temps,humidity, triggering blower to run pretty constantly? How do you feel about the constant wear on the min blower motor.
John your comment with the GBA link isn't coming up. Welcome to dealing with Home Performance Boneheads who "trust the science"... it's early adopter thinking which is fine early on, but not at scale. Note they are using calculations but not looking at actual usage data or other measured data. The 75 cfm is more than most homes will ever get with a scuttle or dehu, and we turn the damper off in high load conditions. They have to absorb the whole argument to catch what we're pitching. Most aren't willing to seriously question "the science", even as we show our hypothesis and data which is, um, science.
You might put in the link to the full series, it required a lot of groundwork to make that argument, if the whole thing isn't taken into account you get "what about..." questions which is what you're seeing.
is this applicable to new construction or just retrofits? I'm in the design phase of new construction. Is there a certain ACH50 below which an ERV is still recommended for IAQ reasons, even if it doesn't save energy?
Both. You may want to watch the whole video and this series. We don’t think ERVs or HRVs should be used in single family homes with rare exceptions.
Instead make sure you have 24/7/365 dehumidification capabilities if you live in a humid climate which is 80% of Americans.
Your calculation examples are only comparing blower wattage for cost which isn’t the full picture of cost. The calculations don’t appear to calculate the difference in the duty of the AC unit which has to cool off either A) the fresh ERV stream or B) the ambient fresh air supply stream. Both A & B incur a latent and sensible load on the AC unit. That difference in latent/sensible load between A & B, and the respective difference in AC unit Kw usage, is the fair comparison.
Ok, show us the comparison if you think it's material. I think you'll feel foolish once you measure and see how insignificant it is, if there is any.
Honestly just vacuum once a day and open windows once a day to air out
1) who has the time and energy to vacuum a full house very day?
2) a lot of places have rough outdoor temps and humidity most of the year where opening windows isn’t a great option. For example, where I’m at in Florida, even when the temps are nice the humidity will make the entire house sticky after opening the windows in just a few minutes.
Ventilating through filtered make up air systems is usually a better (and more realistic) option for most home owners
can anyone offer some bullet-points in summary for those of us who don't have an hour+ to watch this video?
There’s a summary slide repeated throughout.
I listen to it while I drive/ workout.
You could speed up the audio
48:41 Pretty much this screenshot
Yeah, I'm pretty sure this is wrong.
He did his math and showed his. Where's your math?
What evidence do you have to the contrary? Pretty sure doesn’t mean much
@@timdestasiohvac 😂
@@reedieward9079 thought u were replying to me.. my bad.
Prove it wrong.