Well, you guys will hate me, but I want to temporarily hijack this thread for my own benefit. The reasons I am doing this are because it has been dead as of late and because so many knowledgeable people check for updates regularly, I figure, for my own selfish reasons, I could kill 2 birds with one stone.
Because it has been hot as heck up here in the DC area, my AC has been running non-stop over the past few days from 11am to 8pm. While I don't know the exact specs, I have a 4 ton outdoor unit and a massive evaporator trying to cool an old single-level 2100 SQ-FT house. This is a 7 year old Carrier top of the line setup.
I think the major part of the problem is because the ducting is in the attic and it is super hot up there. I was thinking of installing 1-2 thermostatically controlled fans. My attic looks like a T shape with ridge vents throughout, no sophit vents, and gable vents on each of the 3 sides of the T.
My question is simple. Can somebody recommend a thermostatically controlled fan that I can install in front at least one of the 3 12x18 gable vents?
-Stu
You cannot lower the air temperature in an attic space by increasing air flow. Adding vent fans will move more air, but the heat will remain in the space. Attics are supposed to be hotter then the air outside so you will have natural air flow from your soffit vents to your peak or ridge vents. Heat makes air rise, so the air enters your soffit vents and rises inside your attic, then exits through your vents. More vents and adding power to them may increase the speed of this air flow to a small degree, but nothing significant to lower the air temperature.
The only way to cool your attic is to insulate it and duct it. This is becoming common with foam insulation as it's easier to maintain the air temperature in that attic with really good insulation then to fight the difference in air temperature from the attic to the living space below. The cost to do this is prohibitive and why most people don't do it.
You need to have soffit vents. They need to have baffles so the air flows past the insulation. Then you need at least a foot of blown in insulation for R30. I just did my parents house 2 feet thick for R60, which is becoming the new standard. If you can see your rafters, like most houses I've been in, then you need to get some insulation in there.
I like Attic Cat blown in insulation made by Owens Corning. It all costs the same, but their bundles are bigger and cost more, but go farther then the other brands. You buy fewer bundles, but in the end, you get he same coverage as the other brands for the same amount. Home Depot will give you the machine to use if you buy ten sacks. I used 70 on my parents 2,000 sq foot house.
Go over your ducts and look for leaks. Many times I've found where they have come apart at the joints and air is going into the attic space. Seal up all the joints real good and make sure the ducts are wrapped 100 percent with insulation. Use Foil tape to seal everything up. Never used duct tape, it will just dry up and fall off in the heat.
It's an painful, hot, dusty, miserable job to do, but pretty simple except for the pain and suffering of being up there. Do a little in the morning and quit when you get hot, then go back and do some more the next morning. Every little bit makes a huge difference.
Eddie
