Heat recovery ventalator

tax- very common here in alaska. tight houses with little amounts of air change.i,ve installed and us a couple of them. wife likes plants and every one of them is a humidifer. not uncommon to build up 2-3inch ice dams on bottom of windows before using hrv. then when temps outside would warm up ice would melt and run down wall. hrv's work great and you don't have to run all the time depending on inside and outside conditions. better quality air also.

I also have a home with spray foam insulation. My HRV has been running for about 5 weeks now. Prior to its installation I was getting some condensation on the windows, and a little bit from my AC return grills on certain days.
Basically moisture added to the home by cooking, showering, sweating etc. will create enough moisture in a tight house to cause problems.
I recently filed a building permit for a new home- which is to be all closed cell foam insulation. The code official insisted the architect address air quality prior to issuing the building permit. Stay tuned

Rob,here in Nova Scotia HRVs are required by law,(Building Code),to be installed in all new construction.There is a reason for this as you are finding out.Tight houses require a minimum air change to maintain a low humidity level during the heating season,(when the windows are shut),and to maintain occupant health.A properly installed and balanced HRV will provide fresh air to all living and sleeping areas and exhaust from the bath and kitchen areas.They can make a world of difference if your moisture is generated from normal day to day living and cooking but may not handle moisture from such things as leaky basements,unsealed crawlspaces etc.A high capacity dehumidifer may also be in order especially if your family produces an excess of water vapour.Worth checking inti in my opinion.

Earl

I have one installed now in my home but before I had the chance and money to do so I just ran a dehumidifier all year around .

I get a lot of window sweating with ice with temps in the single digits. I have tried everything to control the humidity in the house....

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I eliminated all window sweating and icing by installing the the shrink wrap window film on all our windows...costs maybe 40 bucks and a little time annually. It made a huge difference in the draftiness and comfort level in our 40 year old house.

We have a HRV in our office for air quality. It is an older unit (10 years). The newer units are much better mechanically. We are going to add a HRV in our basement since the windows and doors don't get opened much. With 3 kids and pets on a farm we get enough air exchange upstairs ;-)

HRV's ERV's

Another classic example of how far behind the USA is compared to most of the world when it comes to things concerning energy efficiency. We can thank our big home builders and their lobbies for that. "Just keeping costs down you know".

As far as I'm concerned an HRV should be mandatory in all new construction due to moisture buildup in these new houses that are wrapped and insulated well. Older houses....not so much. I have been on jobsites where a wall of a 10 year old house was opened up and seen the line of mold growing inside the wall at the dew point. These houses don't "breath" like an older home because they aren't meant to. That in itself is a good thing from the standpoint of energy efficiency but the builders forget or don't know about the other side of the equation having to do with correct ventilation. If a house is well sealed you have to find a way to get the moisture out or there will be problems down the road.

I've been looking at the HRVs for a while now. Same problem, new house nice and tight and water condensing all over the windows. There seems to be quite a price range out there for different units. Been looking at the Airiva from www.Suncourt.com not a bad price at local store or on-line ($470).
What do people feel is the optimal humidity level? Right now we 50-53% and that is high enough to cause plenty of condensation.

easternbob said:

I've been looking at the HRVs for a while now. Same problem, new house nice and tight and water condensing all over the windows. There seems to be quite a price range out there for different units. Been looking at the Airiva from www.Suncourt.com not a bad price at local store or on-line ($470).
What do people feel is the optimal humidity level? Right now we 50-53% and that is high enough to cause plenty of condensation.

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Optimum humidity will actually vary with the OD temp. For the 20-30 degree range you can live with 35% but as the temp drops humidity needs to go down. When you hit the 0 to negative range indoor humidity should be less than 25% to prevent condensation issues.

Also be aware that the size of the HRV required will change with the sq ft of the house.

What do people feel is the optimal humidity level?

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Dry enough to keep condensation from happening on interior surfaces of the house but not dry enough that you have blood on your handkerchief when you blow your nose in the morning when you wake up.
I'd say those are the outside edges of the zone I look for.