You could spring for an energy audit that includes a blower test. That would allow you to pinpoint any last areas of leaking (though it shouldn't find many by your desc) and ponit out just how tight your house is.

IMO, the ERV will improve your air quality regardless of how tight your house is.

Besides radon, there other tests that could be done such as CO, CO2, formaldyhide, mold spores that would be a great way to know for sure. However for the expense of the the test, just spring for the ERV. Get the ERV of course and not HRV since you dealt with your humidity.

I guess I will just add the ERV to the ever growing TODO list. Thanks for the input.

I just got off the phone with Broan tech support and have more questions on the ERV's. It appears that the larger capacity Broan units (greater than 3500 sq ft) are designed to run continuously - on either a high or low setting. The smaller ERV unit (designed for a 3500 sq ft house) has a high, low and intermittent setting.

I thought that the ERV would run periodically (say 15 minutes every hour) to bring a new batch of fresh air into the house - and it appears that the smaller Broan works this way. I don't understand why the larger ERV units have to run continuously?

My concern is that with the geothermal system that I have, I don't want to throw away the energy savings I am getting with the GT system by exhausting good conditioned air out of the house. I understand the "Energy Recovery" concept - but how efficient are these systems? How much energy is really recovered between the intake and exhaust?

Another concern I have is the dehumidifier I just installed. It hurts my head to think that this unit will work like a dog to dehumidify the air in the house, only to have the ERV exhaust it out - continously!

Can anyone shed some light on this for me? I know that we get some fresh air into the house since it is not a perfectly sealed envelope (but it is relatively tight.) Having some additional fresh air input peridically to augment the natural air exchange process makes sense to me. However, throwing all of the air out of the house every 4 hours seems excessive, and would likely drive my heating and cooling bills way up.

Thanks

You should be able to find all those stats about the Broan model online. # of air exchanges for a sq ft, and the efficiency of the heat exchanger.

I called Broan back and talked to the tech who specializes in the ERV units. The Broan with the HEPA filter has an engergy exhange efficiency of 62%, while the non HEPA models (ERV100, 200 & 90) are 78%.

The HEPA model was designed to be a standalone install (although other configurations are possible) and cannot tie into the HVAC electronics to operate the fan. If you connect this ERV into the HVAC system, you have to leave the HVAC fan ON all the time. The standalone install looks very simple - exaclty the way my dehumidifier went in. But I don't like the reduce energy efficinecy - I don't need a HEPA filter in my house.

The Broan Non-HEPA models do have an elecrical interface that allows connection to the HVAC fan. I like this approach so that if you turn the ERV off, the HVAC fan will go off too if there was no other demand. I also like the higher efficiency.

The way it was explained to me - the ERV's are designed to be on all the time - to provide a slow steady intake of fresh air while exhausting stale air. They provide a relatively low CFM rate, sort of like leaving a bathroom vent fan on, except for every CFM that goes out, a CFM of fresh air comes in.

I guess I have to weigh the 22% energy cost for the benefit of cleaner air. Accoding to the Broan tech, my new home is probably 8 to 10 times more polluted than the outside air due to building material outgassing.

Some more thinking to do.