we have a 19'x10' HT room with 10' ceilings. it has one 8" vent in the middle of the room and a return over the components in the front of the room. the vent is getting the same temperature (55 degrees when cool air) and air flow as the other vents in the house. the vent works properly also (sucks up piece of paper to prove suction). after watching a movie for about an hour in there, the room starts to get warmer. then the room is about 5-10 degrees warmer than the rest of the house after about 2-3 hours.

the room is over an uninsulated garage, which may be a factor. however, the room gets warm at night when it is cool outside, so i don't think this matters as much especially since we insulated the risers which make up 2/3 of the floor.

what should i do to make the room the same temperature as the rest of the house? should i add another 8" vent? would that be enough?

an A/C person suggesting adding the 2nd 8" vent and making the duct from the plume (sp?) a 12" duct with the 2 8" vents ductwork tapering off from that original duct. would that be enough? he also was guessing we might need a 3rd or 4th vent, but i don't want to effect the rest of the house's A/C conditioning. would a dampering system or independent thermostat be possible and work?

your help is greatly appreciated,
Chris

You have a few options but the best bet is to hire a HVAC contractor that understands home theater needs though good luck finding one.

I had similar issues in my room and extra supplies/returns may help but it would be better if the room was on its own zone or had its own system.

Some easy things to do to improve the situation is to move the equipment and projector outside the room as they put off a lot of BTUs.

Some easy things to do to improve the situation is to move the equipment and projector outside the room as they put off a lot of BTUs.

Or vent the air from the equipment out of the room and possibly out of the house.

Venting out of the house creates negative pressure in the room...not a good plan. That room needs to be on it's own zone and, without knowing the room (heat loss/gain data), I can tell you straight out you're looking at about 8,000 to 10,000 btu's per hour of cooling. That's more than adding a vent.

Overlooking the HVAC requirements of room like this is one of the most common (and unpleasant) factors overlooked in putting together an HT...particularily over a garage in a bonus room.

Stop breathing.

Chris, I went through the same issues you are going through. I have a bonus room above the garage, with 2 1/2 walls being outside exposed walls. When we were building the theater, I called a local HVAC company and asked them to add a second vent and install a return, since there was none. They did it for me and we found out that summer that the combination of the projector and other equipment as well as people (people put out a lot of heat) would heat the room to unbearable levels during the summer. So I called the local HVAC company out again and had them do an evaluation. He looked at the room and the equipment in there, asked some questions such as how many watts the bulb was in the projector and such and then sat down and came up with a few quotes.
1) install a second return and a third vent
2) install a second return and a third vent as well as zone the HVAC (2-zone) to put the theater on the same zone as the upstairs
3) install a second return and a third vent as well as zone the HVAC (3-zone) to have the theater on it's own zone (along with one other room) and the rest of the upstairs on it's own zone and the downstairs on the third zone.

I of course chose the first option as it was the cheapest and the others were looking at thousands of dollars. I also vented the projector into the attic, using an in-line duct fan. I can say that while it was not a perfect solution, it helped quite a bit. I can also say now that by getting rid of the old projector that was like a turbo-jet fan blowing heat out, the new projector is very quiet and also pushes the hot air out slowly (lower wattage bulb as well) and we don't have as much of a problem now at all.

One of the issues with our home is that there is a single HVAC unit and it is either on the edge of not being able to keep up as is, or is undersized, but the builders/inspectors let it through anyway.

Overlooking the HVAC requirements of room like this is one of the most common (and unpleasant) factors overlooked in putting together an HT...


Absolutely. I can attest that the in theater experience will not be enjoyable if you're roasting.

I am going through this exercise right now. My HT will have its own zone (of 3 total) and 2 dedicated 8" supplies plus a 10" return to cut down on the velocity but keep my CFM up. My equipment closet will be in another room and will not contribute heat to the room, only the people and the PJ. It should be quite comfortable once it is done, although having it in the basement will help a bit.

It happens that my master bedroom is above my garage and is ALWAYS 10-15 degrees COOLER than the rest of the upstairs so I am putting it on its own zone. Luckily I have 2 units so it will be easy to do.

John

The previous post mentioned zoning an existing AC unit. Is this something that can be done with an older unit or do you have to have a unit designed to be zoned? Curious???

there is some description here about what it takes to retro fit an existing system.

http://www.smarthome.com/3038.html

Useful diagram:

http://www.smarthome.com/images/zonedhvac.gif

Thanks for the information on zoning the AC. This could solve a lot of our temperature control issues with a theater in a basement tied in to the same HVAC unit the handles the first floor of the house. Up until now it has been hard to please everyone on the two different levels.

You can also do more than two zones if you want more control in more areas.

Zone it or move the thermostat inside the theater. I assume you have a return vent?

That's an affirmative on the return air vent. Construction issues forced me to use one of the bays of the riser but this was lined with ductboard with a couple of s-turns created out of ductboard as well to reduce noise transfer. This vent dumps into the equipment room which as a large return air vent on the opposite wall.
I think that the zoning approach holds high promise. Another possibility is to add an air exchanger in the theater area to moderate the amount of heat or cold that pours in from the HVAC unit.

I have my theater upstairs above my garage also. But, I have a separate HVAC unit for the upstairs. I'm installing Totaline wireless thermostat downstairs and upstairs for just the reason you stated, one room in the house is always way hotter than the rest (our office, because the thermostat is all the way on the other side of the house) So, I'm putting the receiver in the office and the same for the upstairs...replacing the upstairs thermostat and placing a receiver in the theater ;-)