HRV with 85% efficiency?
andy_
| Posted in General Questions on
Other than Zehnder. Nothing against Zehnder other than the $8,000+ install price tag.
I’m building in Washington State (4-marine) and the energy code requires:
“whole-house ventilation requirements as determined by Section M1507.3 of the IRC shall be met with a heat recovery ventilation system with minimum sensible heat recovery efficiency of 0.85”
I called my regular HVAC contractor and he said he doesn’t have anything that meets that requirement and doesn’t know of any other than Zehnder. Anyone have any ideas for a more budget friendly HRV that can hit that 85% sensible heat recovery efficiency number?
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Have you looked at through-wall units? They're usually the cheapest (although still not cheap).
For example the Lunos claims 90% recovery on their website: https://foursevenfive.com/lunos-e/
I think I'd have to get so many of those to hit the CFM needed, that I'd be better off biting the bullet and buying the Zehnder.
I would search through the .xls sheet here:
https://www.hvi.org/hvi-certified-products-directory/section-iii-hrv-erv-directory-listing/
There are a number of erv/hrv with ASRE above 85.
Is ASRE what they're specifying though? That's apparent sensible recovery effectiveness, not sensible recovery efficiency. Is that a direct quote from the code? 0.85 is an incredibly high bar to set, if efficiency is what they're talking about. 0.85 effectiveness would be more reasonable.
Thanks! That's a great resource. I need to make sure if it's ASRE and not SRE.
Lunos is barely enough to ventilate a single bedroom. I'm skeptical of their 90% efficiency claim as well, especially given its flow reversal design. I'm also wondering how effective that is at providing fresh air. Seems to me when the flow reverses that the air being sucked out is at least some of the same air it just blew in. But that's getting pretty far off topic.
Andy,
It seems odd that an HVAV contractor in any jurisdiction where the code mandated certain equipment and efficiency wouldn't have products that met them. Something just doesn't add up. What do they use on all the rest of their jobs?
There's more to it than the condensed for Q&A version of course. In WA we have to get a certain number of points through choices we can make on a list of energy efficient options: http://www.energy.wsu.edu/Documents/Table_406.2_2015_Energy_Credits.pdf
These have to be chosen and locked in at the time of submitting plans for permitting. My designer chose the 2c option since I'm building a really tight house. Unfortunately I didn't look into just what a 85% HRV would cost.
The HVAC guys install a few brands that all hit in the high 70% range since that's what most people do with option 2a or 2b. They're knowledgable and good installers and I should have talked to them first!
Andy,
Ah, got it. Thanks.
85% is frustratingly high. 80% would've been a more achievable target that allowed for some competition. There's kind of a trade off between setting a high bar, and having a competitive market place.
I looked back at my invoices, and a Zehnder CA350 was $2200 a few years ago. This is not much different from comparable units in the >80% SRE category. A lot of what makes Zehnder seem so expensive is the ductwork and optional items like silencers, etc. The silencer is not necessary, and neither is the expensive ductwork. You can install traditional ductwork with a Zehnder HRV.