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Oracle68 08-02-2006 02:59 PM

Hot House
I have a real problem with my house and need advise on how to fix it.

I have the back of my house facing the sun all day long. There is 6 in of good insulation in the wall put in about 7 years ago. There is no ridge vent or other attic ventilation except at the eves. (I can put one in and am planning on doing that within the month.) The wall has old vinyl siding over even older clapboard siding. There is little insulation between that and the outer wall.

I have a pretty good ac, though the unit is old.

There are two air intakes in the house: one upstairs at the top of the stairs and one downstairs in the living room.

Now the problem is that the downstairs turnes into an icebox and the upstairs is an oven. There is good 10 - 15 degree difference in temperature.

I know that there needs to be some attic ventilation. I can and will do that. But I am leary that this will fix my ultimate problem.

I cannot afford to replace my furnace or AC unit.

I have an above average understanding of basic construction, but little experience in doing HVAC or heat/cool stuff.

Any advice is welcome and needed!


cidsamuth 08-07-2006 02:03 PM

That's a fairly common problem, especially when one furnace is cooling both floors.

While you obviously get it, I can't overstate the importance of getting that attic ventilated. With the afternoon sun beating on it, its probably 150 degrees or more up there. While it might not fix your problem totally, you will notice the difference with an attic fan (or two). Also, check to be sure you have adequate insulation on the attic floor. If the insulation is crappy, this will also contribute, as that hot attic air will translate to a hot ceiling on the second floor.

Make sure that your thermostat is placed in a good spot as well. I have noticed that, in some houses, the thermostat will be placed in an area that will give an inaccurate reading . . . such as in the sun, in a hallway where there is no air supply vent, or right beside another heat source.

You can also consider tinting the upstairs windows on the side where the afternoon sun is so tough. Also, are the air ducts sealed, or do they loose cold air at the joints?

My home -- while I have a separate furnace for the second floor, this HVAC still couldn't keep the upstairs below 78-80 degrees on very hot days, even when set on 72 (it would run continuously trying, but couldn't keep up). When we reinsulated the attic (the blown insulation had been stomped down by contractors), it got the air down to 76. Then, I sealed the ducts at the joints (they were blowing cold air into the attic!) and got the temp down to 74-75. I then added a couple of extra supply vents to the hall, given there were none and the thermostat was located there. The temp fell to 73-74. Lastly, I added an attic fan and the temperature fell to where the thermostat was placed . . . 71-72. Not only is it staying at the 72 where I placed it, the HVAC doesn't even have to run continuously to get it there.

All that said, keep in mind that most HVAC "professionals" will tell you that, if you keep the second floor 21 degrees cooler than the temperature outside, you are doing okay. I got mine to 25-28 degrees cooler but, as you can see, it took a lot of work!

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