Temp difference between attic and floor
Last year I started monitoring the temperatures in my attic and the second floor of my home. I purchased a portable temp device that came with a remote unit. I first sat both the base station and remote next to the HVAC control head to determine the difference in reporting (less than 1ºF).
I then sat the base unit in the bedroom I use as an office and the remote unit I placed just inside the attic at the folding ladder that would be the lowest elevation in the attic that was unobstructed of air movement.
This warm season approached and I watched as this computer room would always be 3-5 degrees warmer than any other location on the floor even though I would not have anything running in the room. I also started to notice how quickly the attic warmed and cooled in relation to this room.
So, while I did notice that when the attic was 95ºF the temp in this room was 80ºF (even though the HVAC was set to 69ºF and the coolest room 73ºF). This lent itself to a 15º difference. In the early morning I’ve seen similar difference even though this particular morning the difference is smaller (75/65ºF).
So, I happen to mention this to the wife and she is ‘surprised’ even though I’ve been complaining for five years at how poorly the upstairs cooling system is capable of cooling all but one room on the floor. She only sees the control unit reporting 73ºF and assumes by God’s demand that all other locations on the floor are also 73ºF.
But now I have to wonder what good is it to have 14″ of insulation in the attic if a) my HVAC cannot get the floor within 5º of the attic in the early morning? This is 5º compared to the coolest room on the floor, which is always 5º cooler than any other location on the floor (10º total).
I wish my basement was finished as I’d move down there.
Replies
Odds are your temperature problems are due to duct design and/or installation issues.
I suspect that the room in question has a lot of west and/or south exposure. I would not be surprised if it was the last room in the duct run.
If the duct supplying the room is undersized, it will never deliver the btu's required to cool/heat it. Poor installation (ie: too many elbows, connections with gaps) will be worse than a slightly undersized run installled properly.
If the main ductwork is not sized properly, there will not be enough btu's there for the branch run to that room.
Actually the room in question faces NE-E. :)
The master bath and another bedroom face the W-SW and they are both coller during the day. Go figure. I do suspect the feeds coming from the blower box.
Frenchy, I am jealous. I'd love a SIP home. But you are an exception and an alien (from outer space) if you start talking SIPs in Georgia. Remember, Georgians think insulation is only for Winter weather.
Nuke,
It's your insulation. I have a lazer thermometer.. My ceiling or floor are the same temp within a 1/2 degree winter or summer.. The differance is that my ceilings have 12 inches of solid foam no studs or joists or anything else to conduct heat. (I use SIP's)
Just for the record my ceiling in the great room is 28 feet up while some of the upper bedrooms it's barely 8 feet. same temps.
Try putting an-inline duct "helper" fan (at Home Depot; The Inductor, I think) in the lazy supply duct, and either slave it to the blower fan or add a switch. I used this on a room I used to use on my office (end of run), and it really helped, winter or summer.
Forrest
Presently 93ºF outside, but the attic--lowest elevation--is 100ºF, and the room 76ºF. AC been running non-stop all morning. Its about 3-4ºF cooler in the master bedroom.
Nice idea about the inline fan. I need to get a quote for an attic fan. Or move underground.
You need to do the other checking FIRST. An attic fan can just run up the bills and make it worse.If there are any leaks in the supply (or return lines) then the attic fan will just suck the nice, expensive conditioned air out and into the attic.Checking for loose or crushed lines is the FIRST thing that you need to do.Also before putting in an attic fan you want to seal any and all air leaks from the house into the attic. That includes around light boxes, where wires go through the top plate, where plumbing lines and chases go through the ceiling, where furnace vents go through the ceiling, where the vents and returns go through the ceiling and anything else that I have forgotten.Also what do you have for return air in that room? Unless there is a return in that room then either the door needs to stay open or at least 1" clearance under the door to the finished flooring..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.