Media Room Closet Air Flow

Old 04-22-16, 10:38 AM
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Media Room Closet Air Flow

I want to relocate warm air from a media closet into the next room so it can be routed back into the air return (vs. venting it back into the home theater so that it stays cooler). I was thinking about putting in a ceiling vent and allowing the chimney effect to push the air out of the closet. I have a 1-1.5 inch clearance under the door so i'm thinking that's enough clearance to pull cool air into the closet and move the hot air out the ceiling vent. The only issue is, on the opposite side near the return, I only have clearance on the ceiling to put the exit vent. Will the heat of the closet be able to 'push' the warm air down on the other side passively? I was also planning on including 100-120CFM worth of fans helping push the hot air along as well if....

See rough drawing...

Thanks in advance for any comments...
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Old 04-22-16, 12:28 PM
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Rather than coming down into the ceiling of the next room why not simply tie into the existing return air duct in the attic? I would use either a three or four inch duct and be sure to have an adjustable damper to control the volume of air.

What is the length of the door that has the 1-1/2 inch gap?

I would only use a small fan if the equipment is fairly tightly packed on the shelves, otherwise the airflow through the entire closet should be sufficient. The one possible exception would be if your central HVAC run time is minimal you might want to use a small fan at the duct to ensure air flow through the closet.
Old 04-22-16, 01:16 PM
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Furd, thanks for the response!

I've definitely considered just tying it into the return air duct but I haven't considered it for a couple reasons- 1) Won't I need a full filter on the vent/return so i'm not adding dust/particles into the system? 2) Its a new home and my HVAC is under warranty for a year- i'm afraid if I tamper with it, my warranty might be voided so I figured just rerouting the air "outside the system" was a close/safer option. I did have the HVAC company come take a look and they didn't recommend tying it directly into the return air, but rather putting in a bathroom style vent to the outside. This seems wrong to me from all that I've read so they are already suspect in my mind :|

The length of the door is a standard 6'8" door, 26" wide (closet door).

I do actually already have a digital thermostat with 2 140mm computer-style fans that I was going to use (120CFM total) so figured I might as well use what I have and just set it to kick on when the closet hits 85. Regular HVAC usage should not be a problem though- being in Houston it runs very often.

Thanks again for the feedback!
Old 04-22-16, 01:23 PM
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1. No - you have a filter on the main return before the air enters the furnace and that is sufficient.
2. How much time is left on the warranty? Maybe just wait till it runs out. I agree that their suggestion does not make a lot of sense.
Old 04-22-16, 06:28 PM
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Will the heat of the closet be able to 'push' the warm air down on the other side passively?
I wouldn't think so. I think the heat will still build up in the closet.

It isn't necessarily the best route to dump heat into the return duct but it certainly won't void any warranty. Your HVAC guys sound lazy. It's something I'd definitely try.

Actually, if your concerned with dust.... a filter on the air coming into the closet would be a good idea. It would keep the equipment cleaner.
Old 04-22-16, 07:10 PM
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I would put something like this on your vent duct... they are cheap and surprisingly quiet.

Inductor 6 in. In-Line Duct Fan-DB206 - The Home Depot
Old 04-22-16, 07:52 PM
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You will need a fan to move the desired air as the natural convection for what you are describing would barely move a feather. Natural air flow is powered by a temperature difference and you won't want that room to get up to 140į or more. At 90į you would have less than 0.5 pascal and that pressure across 30 in≤ of opening would move about 10 cfm at best.

Old 04-22-16, 10:21 PM
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Wow thanks for the feedback guys...

It sounds like i'm going to definitely want a fan of some sort...if I did the 2x140mm fans (120 CFM) mounted on a 6x10 vent, that would be enough air flow to push the warm air 15' away and down a foot/foot and a half out of the exit vent?

Still deciding if I want to have someone run the warm air directly into the return in the attic or right next to it in the hallway ceiling...

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