My hot attic - conclusion

[Steve Kulpa]

First off - thanks to all for the comments and suggestions. I finally found my papers from when we bought the house and got ahold of the man who did the inspection. He's very knowledgable about this stuff and he assures me that if I do what I planned on doing - the attic will drop in temperature. This will in turn will allow the heat pump to work better since it's ductwork is in the attic. The end result will be a more comfortable bonus room, a heat pump that does not run as much, and if I'm lucky, an attic that's cool enough so I can use it to store more then just 'hardy' stuff. His reasoning is the R-factor of the ductwork insulation, and the differential between the outside air temp and the attic air temp. He went off on a bunch of stuff about BTUs, and such, which I didn't understand, but since he was helping me for free, I was polite and let him go.

to recap - I have 8 or so static vents on a tall peaked roof, that offer little help in moving the HOT air out of my attic, so I'm planning on replacing 2 of them with powered vents. there is a small heat pump in the attic which serves the ajoining bonus room, which is over the garage. Right now, the bonus room is always warm and the heat pump comes on very frequently, runs for 5 minutes, cools the bonus room down somewhat, then shuts off, only to come back on again in another 10 minutes or so.

His only cautions were: a) make sure the soffitt vents are clear (easy to tell by turning out the attic light and look for daylight). b) cover up all the remaining static vents except for one or two - the furthest away from the power vents I install.

I have a contractor coming next week to do the work and will report back the results - hopfully GOOD results. Yesterday the temp reached

112 degrees F in the attic.

thanks again, steve

[trader4]

112 degrees in a properly ventilated attic is not unusual at all. I don't know what your expectations are, but you may be disappointed.

[Travis Jordan]

Steve Kulpa wrote:.

For what it is worth the unbiased studies on powered vents all say that for homes with adequate ceiling insulation the power ventilator will use more electricity than it will save in reduced cooling costs. OTOH you can cool the attic somewhat which may have other benefits.

[Steve Kulpa]

If it makes the heat pump run less - that's a good trade off imho!

also, there is no insulation under the roof, just above the ceiling

steve

Travis Jordan wrote:

[Steve Kulpa]

That may be true, and would be fine with me, if: a) it wasn't ajacent to the bonus room, which it heats up b) there wasn't a heat pump in there, with all the duct work c) I didn't need some storage place.

I'm disappointed now, so hopfully it won't get worse! :-)

steve

snipped-for-privacy@>

[hallerb]

I think he has a EXCELLENT plan. Inside attic temp is largely dependent on outside temp. I was told a properly vented attic shouldnt be more than 15 degrees above outside temp, that from a home inspector...

keeping the heat pump cooler is certinally a excellent idea

[Steve Kulpa]

Thanks! That's pretty much what the inspector I talked to said too.

steve

[e-mail] wrote:

[PipeDown]

Temp difference is exactly what you need to look at to see if you are successful, the actual temp is obviously dependent on the weather and time of day.

[Steve Kulpa]

[Travis Jordan]

With a white tile roof and a radiant heat barrier, maybe.

[Joseph Meehan]

Nice reference.

[Joseph Meehan]

[e-mail] wrote: ..

15 degrees difference is very little in some areas. A lot of what really is needed and what works and what is normal is area specific.

[Joseph Meehan]

And keep it that way. Insulating under the roof will raise the temperature of the roof to the point it may become damaged. At least that is true for many areas and roofing types.

[Joseph Meehan]

Sorry I missed the first statement. It may not be a good payoff if the cost of running the fans is greater than that of running the heat pump.

Extra note about the heat pump. Since it runs for, I believe you said five minutes and then shuts off and you are not getting sufficient cooling in the room(s) it services, it sounds like you have an unrelated problem with the heat pump or the controls for it.

[Travis Jordan]

Certainly true. For the OP: is the heat pump (I mean, air conditioner) shutting off before the thermostat set point is reached? If so, you've got some other problem.

[m Ransley]

Powered vents, 2? Unless you know how the house is built and how to run the numbers you could Increase the load on the AC by sucking house cooled air through the attic. With 2 units and your inspectors [ calculations ] you probably will. Your attic is not that hot, a properly designed and operating AC does this for millions of people. Get your AC checked first.

[Steve Kulpa]

Sorry, I didn't mean to mislead - the heatpump seems to be working just fine. It comes on, air that's cooler then the room comes out of the vent, it runs for a while (sorry, I was just guessing at the time), the room cools down, it shuts off. Then the room warms back up again (quicker than I'd like) and it starts all over.

The guy I talked too said since the duct work is in the attic too, based on it's insulation R-Factor, the heat pump is working extra hard cooling down the air from the return, which has warmed up some on it's way to the exchanger thanks to the hot attic. By lowering the temperature in the attic, even if it's a small amount, the return air will cool down too, and the heat pump will be able to do it's job easier. Plus lowering the temperature in the attic will help keep the bonus room cooler longer after the heat pump turns off, which means it won't come back on as quickly.

On a side note, the bonus room sits over the garage. It too was very hot during the day, but thankfully it has 2 windows. I placed a window fan in one window, and opened the other half way. Big difference in the garage, which should have reduced the heat in the bonus room too, albiet slightly, but every degree helps.

steve

Joseph Meehan wrote:

[twstanley]

I wouldn't bother with the attic vents. The temperature in the attic you mentioned doesn't seem that high at all. The heat pump sounds like it is working fine.

The problem you mentioned is that the bonus room heats up to quickly, causing the heat pump to come on again sooner than you would like.

It sounds like the real problem is heat gain in the bonus room. Can you find some ways to address that? Is there insulation below the bonus room but above the garage ceiling? Are the walls & ceiling of the bonus room insulated? Are there windows in the bonus room that could benefit from blinds or window tint?

Insulation can be blown under the floor, into the walls and above the room if you discover that it was somehow left out during construction....

Where do you live? Does it get cold there during the winter? Do you have problems with the heat pump running a lot to heat this room during the winter?

I would guess you are not in the frozen north if you have a heat pump.

Steve Kulpa wrote:

[Steve Kulpa]

Don't know about any insulation between the floor of the bonus room and the garage ceiling as I have no access there. I did notice a slight improvment in the bonus room when I cooled the garage down, so maybe there's none? I DO know there's plenty of insulation everywhere else as I can see it from inside the attic.

I live in Nashville. No problem in the winter, the room stays very comfortable. Enough anyway that I'm not concerned. It does get cold, but not too many days near zero, but many between zero and 20. It's the summer and the heat that's driving me crazy.

The attic vents are a done deal, the guy comes on Monday to install them. I HAVE to lower the temp in the attic, period, and it's just not getting done w/ the way it's currently set up. I want some usable storage space (not much, just some), and I want the bonus room to not be so warm (3 of it's 4 walls have attic space opposite them, 1 majorly).

If the bonus room was not ajacent to the hot attic, and it's heat pump was not in the attic, then I'd blow off the storage space and live with it. But it's not and we use the bonus room every day as that's the play room we 'baby-proofed' for our 1-year-old, and I just don't like the way it currently is (temperature wise).

We have blinds and curtians on the window too - it's the &%@(&# attic that's making it so darn hot up there.

I've considered alternatives, and looked into everything else I could try. Powered vents to force some of the hot air out (and cooler fresh air in) sounds like a viable soultion. I'm not looking to make it a living space, just a cool it down a bit (or maybe a lot?).

steve

twstanley wrote:

[CJT]

Steve Kulpa wrote: Yesterday the temp reached

I'd be thrilled if I could keep my attic temperature as low as 112 F.