Noise from ERV in Closet
I am currently doing a self build high performance house 23′ x 35′ interior in climate zone 6. It is essentially a modern raised ranch as the lower level is only 3′ below grade due to a high water table. The upper level has an open concept with 6/12 vaulted ceiling. The only enclosed area is a half bath and walk in closet/pantry area.
My lower level walls are an ICF so getting exhaust and an intake through those walls is not practical. Without a conditioned attic space or a sizable mechanical room, my options are limited.
The north end of the house, essentially 1/3 of the footprint or 12′ x 23′, has all the rooms that will need stale air removed; kitchen, half bath upstairs with the master bath directly below. The main bedroom below will need fresh air. The 7′ x 4′ walk in closet buts up to the master bath. So ideally, installing the ERV in the closet would minimize duct work. Providing fresh air to the upper level should not be an issue. However, the noise factor in the closet could definitely be a factor and make it an undesirable install location.
Any first hand experience relative to the noise production of ERV’s would be greatly appreciated. Thank you
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I built a house with similar dimensions and layout in 2001 and installed a Renewaire ~155cfm HRV. The mech closet was 5 feet from the primary bedroom, separated by a half bath. No issues with noise. I've also installed several smaller Broan and Panasonic HRV/ERVs in small houses without noise complaints. I would recommend the following:
1. Suspend the unit from straps or chains to minimize transmission of low-frequency vibration through framing.
2. Do a careful ASHRAE 62.2 calculation and size the unit accordingly, no larger than needed for general ventilation. If you need more exhaust for bathrooms or cooktop, I'd recommend dedicated fans for those purposes.
3. Select/size the unit for constant operation. I've found that for the low-level mechanical "white" noise, mostly what bothers me is starts and stops. If you can find a unit that can be adjusted so that it can run constantly and provide the recommended cfm, you can pretty much eliminate the start/stop issue.
4. Use the recommended duct sizes, no smaller, to keep velocity low.
5. Use a small amount of properly-installed flex duct adjacent to the unit to provide additional sound muffling.
Great info, thanks for sharing. I’m looking at either Renewaire EVS or the Panasonic Intelli-balance 100. Both units offer variable speed settings which sounds, based on your suggestions, desirable. I’m an owner DIY builder, not by profession. I’m learning as I go and am suffering a bit because these items weren’t planned well in the initial stages. Thanks again.
We've built several houses with concrete floors & no basement. Good place for Lunos units!
I considered the Lunos initially, but did not plan well. Two pairs would be needed and I did not consider the large penetrations in the ICF prior to the pour. They would have been perfect for the upper level. Thanks
Renewaire EV Premiums have EC fans that can be dialed in to the CFM you need. I would assume they are much quieter. The Large seems like overkill but can be dialed down to 40 CFM and has a huge core making it pretty efficient.
At low flow, it won't be an issue. The problem will be is that on boost, you'll hear it. It is not that an ERV is loud on boost, it is just much louder than at low flow, this change is what you'll hear. For example, my ERV is in a cabinet in a kitchen. I never notice that it is on, except when running on boost.
What I would do is frame up a mini cubby in the back of the closet with a door/access panel to the hallway. Install the unit in there and insulate the walls towards the bedroom. This will give you much better sound separation plus it will make filter replacements easier. Jon has some excellent points, make sure to follow both #1, #4 and #5 if you want it to be quiet.
Avoid any PSC blowers, these will tend to have a 60 Hz hum which easily travels through most light weight wood construction. Select a unit with ECM blowers only.
If you are looking to keep holes through the walls to a minimum, look at a dual vent cap. The Panasonic one is only good for 50CFM, the one from Lifebreath is a bit better and good for 100cfm.
There are companies that specialize in cutting concrete; they could easily drill four holes through your ICF; might be worth it.