More than one ERV
the74impala
| Posted in General Questions on
Is it crazy to consider using more than one ERV based on ducting simplicity? I have a master suite and 2 downstairs bedrooms that are sectioned off by framing that will be difficult to duct to/from the rest of the house. Is having more than one a no-no or a legitimate way of dealing with an existing building? Hoping to duct out from bathroom and closets and return to the bed areas.
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Replies
There's no rule here, except the demands of budget. You're trying to save money based on simpler installation, possibly smaller ERV system(s), and reduced ductwork. You have to balance that against the cost of 2 ERV's rather than just one, with the two different duct systems balanced against one larger and more complex duct system. It's tough to do, but try to estimate the total build cost both ways and select the cheaper one. Note that there may be additional savings if one of the systems serves a little-used part of the house, as it could be turned down (or off) when not in use, reducing energy costs. There are a lot of components that would go into a calculation like this and no correct answer. But in short, no, it's not a bad idea to have more than one ERV. They should both be carefully commissioned to make sure they have balanced airflow.
I also don't think it's a bad idea.
It sucks cost wise, but it's awesome work-wise.
I have two smaller furnaces in the last house I designed/built because there was no good way to get through the floors without wasting time and space building vertical shafts and bulkheads.
The house I'm designing now I'm thinking of doing 1 HRV, and 2 ERV's. I just wish they weren't so damn expensive, for what they are (a corrugated plastic core and two little fans). It's a hard to bargain on ROI for a ecm-erv, when I can get an ECM inline blower that has 2-3x the CFM for ⅕th of the cost.
Someone please tell me I'm wrong.
Jamie
Given that small ERVs include the reasonably priced Panasonic units, the two-ERV option isn't crazy at all. And add to the list of advantages the ability to do boost mode for bath ventilation without boosting the whole house.
You might consider using Lunos type HRV, where you rely on pairs of through-the-wall fans with heat-capturing ceramic cores. No ductwork. We've used them successfully in houses where installing ductwork is difficult or impossible.