Encapsulation and Dehumidifier
What do you think is the best way to deal with the air in a crawl space? Vent to the outdoors with passive foundation vents? Add supply air from the HVAC system? Exhaust air to the outdoors with a fan? Install a dehumidifier? All but the first of those assume the crawl space is encapsulated
Rod we use a honeywell humidistat to drive the system. We wire it inline with 3 or 4 receptacles. One of the receptacles is for the dehu and the others are for the fans. We put the fans (honey well desk fans) near the edges to pull air out and push it to the dehu. We always use the same dehu no matter how big the space is with this system. Picture pushing air to the dehu and pulling air away from it in a circle.
Energy Vanguard What type and size of DH do you use, Brad?
Jeff Warden Brad, I'm about to do just as you describe here. Have your heard of any problems with honeywell desk fans being used in a crawlspace? Home Depot has “11” Air Circulator“ fans that look just like the Honeywells. Would that be the right size?
Brad Brinke Those fans are fine. They are inexpensive and run infrequently.
Jeff Warden Thanks Brad.
Sue AndBuddy Spencer Brad, We are purchasing a house near the Tides Inn in Irvington, VA. The crawl space is same footprint of the house at 2130 sf. The 3-ft high crawl space only has a plastic barrier and the sellers had to treat for mold before closing. The soil is a typical sandy-loam in this area, but out of the flood zones. Non-the-less, soil moisture anywhere around Carters Creek is going to be problematic. As I have asthma, I need to do the right thing. My plan was to condition with heavy mil plastic and perimeter 2-inch foam board and sealed vents; install HVAC tubes (just 2) and add a dehumidifier and humidistat unit with failure alarm for dehu pump. Is this over- kill? Should I forget the HVAC vent tubes?
Anthony Grisolia 10 mil
Rod Collins I'd be interested to know more about how you put those together Brad.
Brad Brinke We have a very good track record with the dehumidifier here in Virginia. We install a humidistat and fan system to help the dehumidifier operate efficiently. We tried using supply air from the home and it did not work.
Brad Brinke We use a Santa Fe Compact Air Plus. ES rated, 63 pint. Rated for up to 1600sqft by itself and 3500 with our plan.
Anthony Grisolia Supply air from hvac and install air impermeable insulstion on walls and band area. Use 1mil poly on floor lapped 12 inches on floor and wall. Use 4 inch butyl tape to seal all laps in poly. If you do this you will have no moisture problems.