mtn
I live in the Blueridge Mtns in VA - so probably not that much of a difference in temp & humidity from you. Just finished a new house, moved in this past Jan. I have had to learn a lot about HVAC - and I need an ERV.
The first thing I discovered about mountain living is that we get a lot of fog - it's damp up here. We discovered that during the summer when it was relatively low temp (around 70) the humidity could reach levels as high as 77% in my basement. The AC wansn't turning on which would normally take the moisture out - so it just kept building up in the basement. We started seeing spots on the concrete floor and I thought it was mold. My wife had been smelling a funky odor that would come and go too. Turned out it was moisture - so based on advice I got on the GW, I bought a whole house de-humidifier and that fixed that problem. And I had to get that done first or mold could have started to grow.
Ever since we moved in, but expecially right after we moved in, I noticed that the air inside did not smell good. It was winter time, so we could not open windows to bring fresh air in. I thought it was just out gassing of building materials - and it probably was because - there was very little air circulation. The house is so well insulated and tight, that we don't get the air exchange that we need. So an ERV is on my short list and will go in as soon as I can. I am looking at a Honeywell or Broan ERV that can do the whole house and will tie it into my main heat pump. The ERV makes sense because when you pump conditioned (but stale) air out and bring fresh unconditioned air in, you don't want to waste all of that energy you paid for conditioning the air you are going to push out. They make very cheap air intake systems that just pump fresh air into the house when the HVAC turns on (or it can be put on a timer), but that to me was very inefficient. The ERV makes a lot more sense and will save money over the long term, but it costs more up front. It's a simple heat/cool/mositure exchange system so that the air going out heats or cools the air coming in, and any moist air coming it is rung out before it comes into the HVAC system. That is wht you will see a drain tube on the ERV's - excess mositure has to drain out.
So I have addded humidifiers, de-humidifiers and soon an ERV to my HVAC system. I started looking around for a single control system to tie it all together because I have seperate humidistats and tsats around the house. I am also manually turning on the HVAC fans based on standalone hydometers that I have stationed around the house and it is a bit of a pain but it works (the basement whole house dehumidifier unit comes on automatically with it's hunidistat but it is not tied into the HVAC fans yet, but the humidafiers are tied into each HVAC unit). Turns out that Honeywell makes an IAQ thermostat controller that ties and controls all of these devices together and that will go in when the ERV goes in.
I gathered much of my info on this forum and www.iaqsource.com which sells products but also has a lot of good info on it too. I was wondering if I needed an HRV or an ERV (they are similar but different) and they had a nice write up with temp zones on it to help choose the right device. Just click on the ERV/HRV link on their site and it provides you a nice description and some links.
I have a good HVAC contractor, but I found that they don't know everything. In a way I am glad I have had to struggle through this myself because the cost to have had them install all of this would have been well outside my budget. I have also been able to see the effects before and after a mod. First, a huge improvement in air quality during the winter when I added the humidifiers and then the effects of the de-humidifier in the summer. Even my wife noticed very quickly how much better the house felt when the humidity levels were maintained at around 45 to 50% in the summer, and about 44% in the winter. If you can afford it, IAQ control is the way to go where all of these devices are tied together and contolled via a single Tstat station.
Hope that helps. Good luck.
Q