Well...one thing has been bothering me, which is the amount of time, the dehumidifier runs. Where the heck is the wet air coming from? See the pic from TED below:
I went down into the crawl space and checked the door...and its sealed pretty tightly. I checked all the vents and all were well sealed...except 2, which I added more caulking to yesterday. But...no substantial change in operation. I also checked the plastic and didn't find anything.
Here's my theories:
1) There's some holes at the end of the crawl space that appear to be ports to look at the steel beams under my garage workshop. Some moisture could be coming from there...
2) Some moisture is coming from the house. However...I'm holding 50-55% RH inside the house according to the inside thermostats...so it shouldn't be running unless the RH inside the house gets higher. This could be a factor...but I doubt its contributing.
3) The crawl space is not 100% sealed. I'm sure there's some, but I would think that there isn't enough humidity entering to account for 2.8 pints/day (That's 50 pints/day capacity of the dehumidifier x 24/8.4).
4) The dehumidifer humidistat is too sensitive/not all that great. This wouldn't surprise me one bit...especially since I have the unit set to maintain 60% RH and the wireless sensor nearby is showing 55% RH. I could setup the dehumidifer to only operate for X hrs/day (I think its limited to 3, 6, 8, or 12 hrs.) I may try that to see how it works. I'll try it low...like 3 hrs to see how well it does. Generally, humidity is highest in the morning...so I'll have it run then.
So...overall, I think I'll buy some spray in foam to close those holes/ports at the end of the crawl space. Then I'll setup the demudifier to only operate for a set amount of time. And then I'll monitor some more.
The spray foam roofing can be very beneficial in homes and can be the essential part of improvement in many homes.
ReplyDeleteYes, that's true. However its generally cost prohibitive. Your money will probably be better spent just putting in more insulation. Once spray insulation becomes more widespread and costs come down, there's no doubt spray insulation is the way to go. And encapsulating the attic is great.
ReplyDeleteTalking with a colleague at work about this, he had an interesting theory to my dehumidifier issues:
ReplyDeleteThere isn't enough air movement in the crawl space. When the unit turns on, its creating a dehumid "zone" which reduces the humidity and the unit turns off. After a couple minutes the rest of the air "diffuses" an the humidity is back high again...and the unit turns back on.
He gave a great example of how he had a dishwasher leak into his basement at his old house. The contractors who fixed it had 4 huge dehumidifiers run for 2 weeks.
According to specifications, my dehumidifier of moving 183 cfm on high speed. My crawl space is roughly 1300 sf and varies from 4-ft to about 3-ft tall. Let's say 3.5-ft average. That's 4550 cf of air. So in theory it takes ~25 minutes for the unit to treat "all the air".
So, maybe I'll have it run for a week and I'll install a box fan too to move the air around.
I don't have a fan, but I can pickup a cheapy at Walmart this evening.
I'll keep you posted...
FYI...running this for a week at 25 min/air change will result in 403 total air changes.
ReplyDeleteThat should get all the air plus any excess water in the wood...