# Basement theater warmer than rest of the house



## Guest (Nov 4, 2007)

In the winter, my newly completed basement theater is pretty much comfortable without any heat on. I just finished at the end of the AC season, so I only had a short time to compare cooling. This morning, the house was 63 and the theater was about 69. When we turned the heat on (single zone), the house warmed up nicely and the theater felt like an oven. The theater has a supply and a return. It is closed off from the rest of the basement. It's not air tight (drop ceiling), but without any ventilation it's pretty stuffy.
I wonder if I should push air into the theater from another part of the basement (cooler). I could close the damper on the basement supply and leave the return open (~72"sq). I was thinking about an inline bathroom fan (again, pushing into the theater). The room is roughly 3000cf.
Thoughts on this idea? Other ideas?
Thanks.


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## Mike P. (Apr 6, 2007)

My home is single zone also. I "even out" the temperature in various rooms by adjusting the dampers in the warm rooms. Try that first and see if it works for you.


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## bpape (Sep 14, 2006)

Providing just an air exchange into and out of the room with no tie in to the HVAC system can be very effective. Since you're already not isolated due to the drop ceiling, you can pretty easily add some simple ducting with a switched fan to draw air out of the room which will naturally create a vacuum to bring cooler air in.

Bryan


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## Guest (Nov 5, 2007)

Thanks Bryan. Suck instead of blow. I guess I could put the sucker vent near my projector (been thinking about that for a while anyway).
Any recommendation of how many CFM to get? Or...how many times/hr to turn the air over? Do you think a not tightly built room has enough gaps in it to make up this air? Should I put a vent in the ceiling that opens into "cooler" space?
I've been looking at something like this...
http://www.kitchensource.com/bathroom-fans/fv-nlf1.htm
It would allow me to get the fan noise away from my theater.

Thanks again.


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## SierraMikeBravo (Jul 1, 2007)

Scott,

You will notice a biiiig difference in that basement temperature come January/February. The diurnal temperature cycle of the ground is offset by about 3 to 4 months in comparison to the air which is dependent upon how cold the air gets for a period of time. So, it will take several months before you realize how cold the basement gets. In addition, with the tilt of the Earth at a maximum away from the Sun on December 21st, we are only just starting to get less insolation by the Sun on the ground which will further reduce the temperature. My guess (depending on how cold the winter months get in the Northeast) is that your basement temp will drop by about 5 to 10 by February. So, don't be fooled.


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## John Simpson (May 10, 2007)

Hot air rises, pulling cool air into the space it occupied -- so having a basement hotter then the rest of the house is an achievement! If you add a high vent for air to leave and a low vent (ported if needed) for air to enter, thermal pressure will do the job for you.


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## Guest (Nov 7, 2007)

Thanks everyone. Based on responses, I guess I'll wait and see how it does later in the season. I'll try to run the house fan for a while before and while I'm down there.
I have an idea on how to automate the fan (maybe 10 minute cycles on and off) when the projector is on (a good bet that people are in there).


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## tonyvdb (Sep 5, 2007)

I work in the HVAC industry and can say it easier than you may think. If the theater room is warm and you have a dropped ceiling all you need to do is allow the warmer air to escape into the space above the ceiling by placing one or two vents or egg crate grills into the ceiling tiles (does the space above open up to the other part of the basement?). This will allow for natural convection of the warm air pulling the cooler air in.
Close the vent on the supply air into the room and open the return this will also move air around providing the room is not completely closed off from the rest of the basement.
Another thing you can do is have a vent near the floor that is simply a pass through to the other part of the basement. This will allow the cooler air to get into the room.


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