Southeast Tennessee. A little winter and a lot of summer. :^)
Let me recommend a product which has proven highly effective in retrofitting many structures in hot/humid climates. http://www.thermastor.com/pdf/ua3fold.pdf
I'll look into that!
(No, I have no financial interest in the company!)
The company doesn't seem to understand what they have here, so they don't promote it properly, but the contractors and consultants I work with all over the South are highly impressed with its effectiveness, in many cases.
It's a HEPA air cleaner and high-efficiency dehumidifer that attaches to your existing HVAV system. It takes humid outside air and dehumidifies it deeply, then injects it into the structure. A friend of mine in Tampa is able to maintain his interior below 50% RH even during the most severe conditions.
Interesting. I'm going to look at it, but I'm not sure if it can be applied to my situation or not. I have reasonably dry air upstairs even on the most humid days; typically 50-55% RH. The problem as I see it is downstairs. Its cooler down there, 5-10 degrees typically. Because of that, the water capacity of the air decreases, and if it is humid enough outside, I can actually get condensation on walls. Prior to dehumidification, this was most likely to occur on a day when A/C use was minimal, say cloudy, 80 degrees, and 95% outside RH. This isn't a leak issue; it is a humidity issue.
My solution has been to run a dehumidifier downstairs in the summer, particularly on those not-so-hot days when the A/C duty cycle is low. It is effective and keeps things at 50-55% down there. I suspect that if I had a really large unit or two units, I would have no problem keeping it down around 40% but I think that may be overkill. I'll monitor the situation closely. BTW, I usually use HEPA or close to HEPA filters. I have a 20X30 size filter grill so restriction is quite low.
A beneficial side-effect is that it positively pressurizes the structure, limiting intrusion of hot/humid outside air.
OK, I'm not sure how this works. Does it have a forced air fan pushing air into the house?
Cost: around $3k installed. A major bargain, IMHO.
I'll look into it. I'm not really dissatisfied with what I'm doing now, but I want to monitor it again this spring and summer. Its plenty dry in here now with the FHA furnace and cool outside air keeping humidity down. Its around 38% right now.
There are both positive and negative energy usage effects, which vary by structure. In most cases, I suspect there would be little or no net energy usage increase. But a huge increase in comfort and livability. Not to mention an enormous decrease in the likelihood of mold growth.
Thanks!
I had the same sweating problem in my walk-in basement. Not only did the concrete walls sweat, but the cold water plumbing (copper), the toilet tank, and the pressure tank for the well. The "junk" I have stored down there was getting green mold (mildew?) all over it, and metal tools were rusting.
A small DeLonghi dehumidifier completely solved that problem. I ran it round the clock all summer at very little cost in electricity. It kept the basement at 60%RH.
When we had our annual pest inspection, the pest control company made a note: "Dehumidifier in Basement". I assume that's because they are liable for wood rot.