Advice on air-conditioning a 20m2 home theatre room... - AVS Forum
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post #1 of 6 Old 06-24-2012, 12:57 PM - Thread Starter
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So here's the deal. I've bought an old house and will convert one of the rooms to a dedicated listening room/theratre. Where I live it is not actually not that warm during summers (equal to Juneau Alaska) but we have extreemely high building standards when it comes to insulation and energy conservation. Basically, no heat leaks in to the building and no heat dissipates... As part of the renovation I'll install a super energy saving "geothermal well heat-pump". Apart from harvesting ample amounts of energy from the well during the cold months, I can also dissipate ample amounts of heat down the well during the warm months, i.e. I get air conditioning pretty much for free (the energy to make 8-10kW cooling power is equal to the energy drawn by a couple light bulbs smile.gif.

Thing is that no one up here seems to know how to dimension ducts etc. for a home-theatre when it comes to noise. My calculations indicate I need between 1 and 3 kW cooling in the room to be able to keep a nice 20-21 centigrades in there during summer months with equipment running and a coupe friends in the room.

Since I know there's a lot of knowledge about these things here I thought I'd ask for input -what sound levels and flow to aim for (size of diffusers etc) for decent sonic performance as well as other things to think about sound wise. I beleave the most scilent solution is to place a cooling unit away from the room(s) in the attic and the use "oversize" ducts and diffusers to keep the flow through them low.

thoughts?

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post #2 of 6 Old 06-24-2012, 01:27 PM
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The rule of thumb everyone uses here is to design the duct for velocity not to exceed 250 feet per minute at the registers. So the general process would be to figure out the volume (cubic feet per minute) that you need to heat/cool the room, and then size the ducts to be ab le to move that volume at 250 feet per minute.
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post #3 of 6 Old 06-24-2012, 02:00 PM - Thread Starter
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Quote:
Originally Posted by LeBon View Post

The rule of thumb everyone uses here is to design the duct for velocity not to exceed 250 feet per minute at the registers. So the general process would be to figure out the volume (cubic feet per minute) that you need to heat/cool the room, and then size the ducts to be ab le to move that volume at 250 feet per minute.

My coolant will be between 5 and 7 deg. C which will give me around 10-12 deg. air temp from the unit according to the manufacturer.

OK....so according to my coolant temperature (7 deg. C) I'm looking at about 300l/s, which computes to 18 m3/minute… If I want it at a speed about 80 m/minute (=250 ft/minute), that's computes to a Square area of 18/80=,225m2.

All in all, I'd need a duct (or atleast outlet and return) of about 0,150m (6")?!??! Dosn't sound much at all...but I might have done my calcs all (or partially) wrong?

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post #4 of 6 Old 06-24-2012, 02:24 PM
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If you need a cross-sectional area of 0.225 sq. m, that is more like 21 inch diameter pipe (just rough estimation), isn't it?
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post #5 of 6 Old 06-24-2012, 02:55 PM - Thread Starter
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Quote:
Originally Posted by LeBon View Post

If you need a cross-sectional area of 0.225 sq. m, that is more like 21 inch diameter pipe (just rough estimation), isn't it?

Humhum... Let's see now (chough chough)… 0.225m2 area... A=pi*r^2 => => d= 2* sqrt(A/pi) => d=0.53m => 21.4" redface.gif That makes more sense smile.gif

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post #6 of 6 Old 06-24-2012, 04:08 PM
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haha don't feel bad, I made the same mistake. Do all that complicated math, then drop the ball at the last step smile.gif

I'm assuming you will go with rectangular or multiple round ducts?

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