Panasonic ERV question
Hey, I have a Panasonic FV-10VE1 installed and just moved into the house. I just turned it on and tested the static pressure and the stale air came out as 0.03 kpa and the fresh air was 0.08 kpa. These were both measured at 100 CFM. What do I do now? I don’t really understand how to balance it now. Ideally my HVAC guy would do this but he knows nothing about these.
Background: It’s a new build about 2500 sqft over 3 floors in Asheville NC. pretty tight house with 2×6 walls (R21) and vaulted ceiling with spray foam (a bit over R40 open cell in the roof). The ERV is on the 3rd floor with 2 intakes and 2 outlets near the HVAC returns. It is ducted desperately
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David,
You can hire a Resnet energy rater to balance the system. There should be several in your area.
Also...
Talk to the rater about maintaining safe humidity levels. All that open cell foam in the attic is a potential issue if levels remain too high.
Both numbers are well within the spec of the unit. These are designed to auto balance, as long as you are not exceeding the static pressure, the unit handles balancing automatically. Just set the dials on the unit to the flow rate you are looking for.
P.S. Steve point is very important, you should have some hvac supply in the attic. With the ERV if you have enough capacity (need around 40CFM), the simplest would be to run a stale air pickup near the ridge and use that. This would draw in conditioned air from the rest of the house while exhausting any left over foam smell.
Thanks for getting back to me! Akos....when you say set the dials to the flow rate I'm looking for, What should it be? This is my first venture into ERV's and don't know much about them.
The attic really isn't an attic per se. It's finished with 5/8 drywall in the vaulted ceilings. The ERV intake on that floor is half way up the roofline. I wanted to go near the ridge but would have lost a lot of insulation since the drywall is attached to the underside of the 2x rafters. We also have a panasonic bathroom fan in the bathroom on the top floor as well.
Since the attic is finished, means that it is connected to your house AC. That is all the conditioning it needs.
Flow rates depend on your local code. Ours is 20cfm for master and basment and 10cfm for each additional room. My guess based on your sqft, it should be set to max. If you have only two people in the house, you can reduce it a bit. Grab a CO2 monitor and keep an eye on levels. Generally you want bellow 1000ppm.
Just to be clear, pulling ERV exhaust from a sealed attic (edit: if present) might require X CFM, but it doesn't need X *additional* CFM. Ie, it should pull from the house, so it counts as house ventilation.
In any case, might be worth it to monitor upper sheathing moisture content to verify that it isn't accumulating moisture.
DavidLLarsen,
Check out this article on ventilation: https://www.greenbuildingadvisor.com/article/how-much-fresh-air-does-your-home-need.
The Panasonic should have plenty of capacity for meeting your needs. Do you have boost switches in the kitchen and baths? That would be a plus.
It sounds like you have cathedral ceilings in a finished attic. So you should also read this article: https://www.greenbuildingadvisor.com/article/how-to-build-an-insulated-cathedral-ceiling.