HRV problems vs ERV

Craig808

Someone came in and was suggesting a PANASONIC ERV, not sure if that was mainly because he had it in inventory or not, but he said it's one that won't freeze up in minus -30 weather. (Ottawa, Canada)

The implication is the other models are prone to freeze up and below -25 they won't be working all the time? Is that accurate of say Vanee, or Lennox HRV/ERV's?

Feels like I'm choosing between HRV's letting too much humidity in during the summer or ERV's letting in too much humidity during the winter.

With HRV's also letting too much dry air in the winter and potentially freezing up during the winter.

So are these problems with HRV's accurate?

Jamie Hall

Couldn't answer that -- but there is a critical difference between the two to consider. An ERV will essentially recycle the moisture in the outgoing air, to return it to the incoming air. This is not always quite what is wanted, as that moisture will also contain a number of water soluble compounds, such as some odours, as well as airborne dust, bacteria, mold spores, virus and the like. Not always quite what is wanted.

On the other hand, they do recover a good bit more of the heat.

Craig808

Jamie Hall said:

Couldn't answer that -- but there is a critical difference between the two to consider. An ERV will essentially recycle the moisture in the outgoing air, to return it to the incoming air. This is not always quite what is wanted, as that moisture will also contain a number of water soluble compounds, such as some odours, as well as airborne dust, bacteria, mold spores, virus and the like. Not always quite what is wanted.

On the other hand, they do recover a good bit more of the heat.

Well there is a concern with humidity in the winter. Ottawa has had more cold wet weather the past few years.
Early and late winter it's gotten very muggy.

I was wondering, would adding a whole house dehumidifier be compatible with an ERV? Just to counter it if there is TOO MUCH humidity?

Or would those two systems just be constantly fighting each other or be contradicting each other?

The alternative would be an HRV, where there are concerns with air that's too dry for too long, system freezing up or too much humidity in the summer.

Jamie Hall

Excess humidity is almost never a problem in the shoulder seasons and winter, when the house is being heated -- since heating air lowers the relative humidity (it doesn't change the dewpoint). From that standpoint, the ERV, which does recover a good deal of the water in the air, has a slight advantage. For me that has never overcome the disadvantage of also recovering a good fraction of the indoor air pollutants is a deal breaker. On the houses I've been associated with where ERVs or HRVs have been used, the main idea is to improve indoor air quality -- which HRVs are much better at than ERVs (assuming the outdoor air quality is good...).

I realise that that really isn't an answer. The main thing to focus on with regard to humidity is not the relative humidity, but the dew point. I would much prefer a system where I could manipulate the dew point separately from the temperature, using a dehumidifier or a humidifier, as required.

Craig808

Jamie Hall said:

The main thing to focus on with regard to humidity is not the relative humidity, but the dew point. I would much prefer a system where I could manipulate the dew point separately from the temperature, using a dehumidifier or a humidifier, as required.

Yeah I did get a humidifier, a $700 unit. I have a heart condition and some breathing issues and the cool mist did not agree with me, it felt more stuffy. I understand there is a more sophisticated version that's more expensive.

I can ask the technician if he thinks an ERV plus a dehumidifier is compatible or contradictory or not.

I was wondering about that here in case he just says yes to anything to make a sale.

The main reason I'm feeling ERV over HRV is the concerns I mentioned in OP, that it might freeze up in -25 weather, but I take you're not in Canada so not everyone has heard of that.

Otherwise I could go with a good brand of HRV and higher end humidifier for the winter.

If I'm considering an ERV with a whole whole dehumidifier the cost might be comparable.