Venting an enclosed TV space?

[Steve]

I cut a hole in a wall to insert a 27"TV. The hole aligns with a stairway on the other side. (about 8 steps.) So the Tv fits into the empty space under the stairs. Its a split level house. One level in front and two levels in the back. 1/2 set of stairs lead down and another 1/2 set of stairs lead up.

Not a huge space but enough to hold the TV. I'm concerned with the heat generated by the TV causing the TV to overheat. I plan on installing a small fan to vent the space.

There is a large closet next to the space that I can cut a hole through to put a small fan in.

Would I be better to Pull air into the space and it would exit out the front around the TV? Or should I turn the fan around and pull air out of the space, sucking air in from around the front of the TV and blowing it into the closet. ( the closet is always open. Its got louvered bi-fold doors).

The opening around the TV is about 1/2" on each side and 2" on the top. I'm going to put a remote temperature sensor inside the enclosure to see how hot it gets.

I hope to figure a way to have the fan turn on automatically when the TV turns on?

This setup works out well. clears floor space in an already crowded room.

I started cutting the hole the other day while my wife was out shopping. Ha, ha ,ha! She just shook her head!

TIA for any Ideas.

Steve

[Brian Dors]

I would have the air flowing from the room the TV is in back into the closet. If you think about how a TV naturally radiates heat, it normally has the heat rise out the back. A slow fan sucking air would encourage this. A fan blowing could perhaps end up pushing the heat down and keeping it bottled inside the TV.

I would stick to a low RPM fan, and perhaps instead of wiring it to power up with TV use a thermostat instead. Good luck, sounds like fun.

[nicksanspam]

So the top of the stairs is about 4' above the base of the TV...

The cooler the better, but 80 F is probably OK.

I'd cut holes into the closet near the TV base and the top of the closet.

If the TV uses 150 W (512 Btu/h), a 512/10 = 50 cfm airflow would make a 10 F temp rise from 70 to 80 F... 50 cfm = 16.6Asqr(4'x10F) makes the vent area A = 0.47 ft^2, eg two 2'x3" slots.

Nick

[Michael Daly]

It's almost always easier to suck warm air out than to force cool air in.

I'd consider having the fan draw air out of the closet and just put a vent between the closet and TV enclosure. You'll have to get the closet relatively airtight for it to work well.

If not, make sure the closet is vented at a high spot so that the warm air introduced has a place to escape.

Remember that whatever is in the path of the air coming out of the fan or vent will be bombarded with dust over time. If you've got something like clothes in that closet, they'll get dirty if they're near the air flow. They'll get black if there are smokers in your house.

Use a cheap thermostat of appropriate voltage capacity to turn on the fan when the temperature in the TV enclosure exceeds room temp by some amount. You can experiment to find the setting you're happy with. That means it will continue to vent if the TV's still hot after turning it off.

Computer muffin fans can be used for this. The good ones are quiet. You might need a wall wart to convert 120VAC to 12VDC - just watch for the amps being pulled - don't use a 300 mA wall wart for a 750 mA fan. You can put the wall wart on the controlled side of the thermostat so that it only draws power when you need it - standby is only a couple of watts, but... I don't know what the code says about temp controlled 120V sockets, though.

One other thing - some TVs never turn off. They go from full power to reduced power and keep the picture tube heater running for "instant on". You may want to plug the TV into a power bar and shut that off when the TV's not in use - you'll save electricity and guarantee that there's no heat generated unless you're watching.

Mike

[Chet Hayes]

What's the volume of the space the TV is in? With today's TV's being mostly solid state components, they don't generate much heat. Before I wasted time and complicated things with a fan, I'd put the TV in the opening, with a thermometer in the space. Leave it on for a few hours and if the temp is within the operating limits of the set, I wouldn't worry about it.

[Tom Baker]

"International Residential Code, Sec R314.8, Under stair protection. Enclosed accessible space under stairs shall have walls, under stair surfaces and any soffits protected on the enclosed side with 1/2 inch gypsum board." This is to protect the stair from burning before you can get downstairs and away from danger. I'd suggest making that enclosed, inaccessible space as fire safe as possible if it is to contain a TV. I would vent it to an accessible space such as the viewing room, rather than into an enclosed space filled with flammable material.

If there were a grille below and a grille above the TV, I should think air would circulate enough without a fan.

TB

[Steve]

Excelent point!. Thats why I visit this NG!

I hadnt considered fire. I was worrying about overheating the TV.. Duhh!

TV is already there and it looks great but I will reevaluate the venting.

Does this mean I should cover the bottom of the steps with a 1/2" piece of sheetrock?

There is about 1.5" opening above the TV. No room to put a vent above that. I can add a vent below the TV.

Now I'm back to sucking or blowing the air.

The only opening in this space is around the TV sides and top so if I suck air into the space it would pressurize it and air would be forces out around the TV blowing the hot air out.

If I blow air out the vent it will pull air in around the TV sides and top and vent it out the bottom. only problem here is that heat rises and my vent would be on the bottom.

I'm going to check operating temperatures this weekend with a remote temp sensor.

What do you think would be considered to high a temp. ???

Thanks again!!

Steve