Air to Air exchangers?

[Dean Hoffman]

We have the basic problem of too much moisture in the basement of Mom's farmhouse. We have a dehumidifier which helps a lot. Are air to air exchangers a better alternative?

Thanks muchly gentlemen

[clare]

Sometimes a sump-pump works better - but air to air heat exchangers (heat recovery devices) ARE quite effective.

[mike]

Effective at what?

The problem statement is so vague that it's hard to say what is happening, much less how to fix it.

1)fix the way the moisture is getting in. 2)depends a LOT on the conditions.

IN the case of humidity, there's an interesting online calculator that relates humidity, temperature and the probability of mold growth.

Depending on the problem you're trying to solve...if it ain't broke, don't fix it.

[trader4]

n

Since it's humidifier vs air exchanger, I'd assume it's humidity that he's talking about, but you're right, not much to go on. The advantage of an air exchanger approach is that it replaces the air, so it can help if the basement has a smell, even with the dehumidifier. Not sure on the efficiency of one vs the other and how they compare in energy usage and loss.

I can tell you one thing that I think is a waste of money. That is the Wave thing that is advertised on the radio all the time. From what I could tell, it relies on just venting basement air outside and replenishing it with air coming from upstairs in the house. They claim it costs very little compared to a dehumidifier and gives you fresh air. It's operation sounds right, but from what I can see, they are comparing the energy used for it's fan to that of a dehumidier. They completely neglect that the air that is being pulled from upstairs winds up replaced with outside air. That means if you're heating or cooling, you've placed a big additional load now on the HVAC. It would be like placing a fan in a window, blowing air out. And then there is the fact that it costs 10X what a humidifier costs and it's bascily just a fan with a humidistat.

[clare]

Effective at lowering interior relative humidity in the winter. Possibly more effective than his present dehumidifier. But like I said

- a sump pump MAY be more effective.

[trader4]

en

Well, I guess a sump pump may be more effective if the basement is flooded. That would seem to be unlikely

[mike]

We need more info. I have a lot to say about HRV's and use a homemade one myself. But it's pointless to discuss if it's not in the solution set.

A basic HRV does nothing zero, nada to reduce humidity. A fan can reduce humidity by blowing out wet air and replacing it with drier air. And that only works if the outside dew point is significantly lower than the inside dew point...and in particular if the dew point is below the surfaces in the basement. That's why I linked the dpcalc site. It saves you the trouble of navigating the psychrometric chart and also gives you some idea of whether mold is likely to grow.

You MUST keep all the surfaces in the basement above the dew point of the inside air...and that's often higher than the dew point of the outside air...unless you use a dehumidifier.

AFTER you determine that exchanging air solves the problem, you can employ the features of the heat exchanger to reclaim some of the lost energy.

If you can't arrange it so that venting solves the problem with passive thermodynamics, you don't have much choice other than a dehumidifier...AND preventing air influx to the greatest extent possible.

And all this assumes that water isn't seeping in somewhere. It's not a simple problem.

[Dean Hoffman]

Yes, the problem is excessive humidity. There are no problems with seepage as far as I know. The dehumidifier works but I was wondering if the air to air exchangers might operate cheaper. It was curiosity that prompted the question more than anything. This is in Nebraska so the outside humidity should be lower than the basement's frequently. I really haven't done any research on that though.

[trader4]

tlemen

Of course it can reduce humidity in the basement. It depends on the humidity levels and temperatures of the air being exchanged.

Which contradicts what was said above, no?