Can I exhaust a media/networking closet into return air box?

14,839 Views | 20 Replies | Last: 5 yr ago by gansito
stridulent
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AG
I am working on setting up a networking/media closet that is directly next to a return air vent in the ceiling. A lot of recommendations online say to vent the closet back into livable space so that a vacuum isn't created that will suck in heat from the outside through windows/doors/etc.

Is it possible to vent this directly into the return air box? If so, what kind of fan should I use and what kind of materials will I need? I am pretty handy, but have never ventured into A/C, ducts, etc.

Thank you for your feedback.
ABATTBQ11
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AG
I would not do it. That will suck in the summer because you'd be constantly pumping hot air into your intake, making your A/C work a little harder. Granted, it would have to cool that air anyway no matter where you dump it, but if it mixed with cooler air first it would not have as high of a temperature delta when it hits the coils. That means what comes out of your registers would be a little cooler.

It would be most efficient if you child push it outside in the summer, like a dryer vent is, and direct it to a large room in the winter.
The Fife
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Why not just run a HVAC register into the room? That's what we did, but the media closet hasn't existed more than 4 or 5 months so it's not like we've been through a summer yet.
stridulent
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AG
The Fife said:

Why not just run a HVAC register into the room? That's what we did, but the media closet hasn't existed more than 4 or 5 months so it's not like we've been through a summer yet.

So just have a register that looks like a normal HVAC register but it'd be tied to the closet and a fan?
The Fife
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No, I just extended the ductwork from an adjacent bathroom. A large Onkyo receiver is on whenever the tv is on, plus a cable modem and router 24/7 and occasionally an XBox or Playstation and I haven't noticed any heat issues.
stridulent
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AG
The Fife said:

No, I just extended the ductwork from an adjacent bathroom. A large Onkyo receiver is on whenever the tv is on, plus a cable modem and router 24/7 and occasionally an XBox or Playstation and I haven't noticed any heat issues.

Oh you are talking about putting cold air into the closet instead of removing hot air? I don't think that would work. The closet isn't a walk in. Its only about 25x25 inches.
YellAg2004
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AG
What equipment are you putting in there? I have a small networking closet like that and I thought I might end up having heat issues, but none of the components generate enough heat for it to be an issue. If you have enough components to where heat is an issue, I could think of a few different ways to handle it.

1. Do what you originally suggested. IMO, unless you're running a few rack-mount servers, the amount of "hot" air being added to the return air would be negligible to actually make a difference for your unit's efficiency.

2. If you have attic space right above, add a vent fan that just vents into the attic space. You could even wire it with a temperature switch so when it hits XX*, the fan kicks on and runs until the temp drops, then turns off. I don't see a reason to vent it all the way through the roof unless you're just determined to.

Like I said, it all depends on what you're running and how much heat is generated, but in my experience, my concerns about heat creation and ventilation in my network closet ended up being overblown. Depending on the access above or next to the closet to add ventilation after the fact, you may just install all your equipment and see how warm it actually gets in there under normal operations.
Gary79Ag
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AG
stridulent said:

The Fife said:

No, I just extended the ductwork from an adjacent bathroom. A large Onkyo receiver is on whenever the tv is on, plus a cable modem and router 24/7 and occasionally an XBox or Playstation and I haven't noticed any heat issues.

Oh you are talking about putting cold air into the closet instead of removing hot air? I don't think that would work. The closet isn't a walk in. Its only about 25x25 inches.
I agree with Fife as I'd just add an jumpered ductwork A/C register and then trim up the bottom of the closet door an inch or so to allow the adjacent air return to draw return air under the door.

That's what I'm going to do when I install my media room.
stridulent
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AG
YellAg2004 said:

What equipment are you putting in there? I have a small networking closet like that and I thought I might end up having heat issues, but none of the components generate enough heat for it to be an issue. If you have enough components to where heat is an issue, I could think of a few different ways to handle it.

1. Do what you originally suggested. IMO, unless you're running a few rack-mount servers, the amount of "hot" air being added to the return air would be negligible to actually make a difference for your unit's efficiency.

2. If you have attic space right above, add a vent fan that just vents into the attic space. You could even wire it with a temperature switch so when it hits XX*, the fan kicks on and runs until the temp drops, then turns off. I don't see a reason to vent it all the way through the roof unless you're just determined to.

Like I said, it all depends on what you're running and how much heat is generated, but in my experience, my concerns about heat creation and ventilation in my network closet ended up being overblown. Depending on the access above or next to the closet to add ventilation after the fact, you may just install all your equipment and see how warm it actually gets in there under normal operations.

3 x A/V receivers, 1 x network server, 2 x blu-ray players, PS4, HDMI switch, ethernet switch, modem, router, roku.

Is it up to code to vent into the attic? What kind of switch/thermostat should be used to control the fan, could you link an example please?
txag2008
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AG
There's many different options for control. Here's something simple that you could even get from a big box, http://m.homedepot.com/p/Master-Flow-Manually-Adjustable-Thermostat-for-Power-Vent-PT6/100098472

Or could use something like the following that just controls a standard receptacle. http://luxproducts.com/WIN100.html
bco2003
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The Fife said:

Why not just run a HVAC register into the room? That's what we did, but the media closet hasn't existed more than 4 or 5 months so it's not like we've been through a summer yet.

What happens in the winter when you're dumping hot air into the room with hot devices? I get it, the ambient temperature is cooler because it's winter, but for an interior small room, can see how things could get extra toasty.
The Fife
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Move the lever on the register and shut the airflow off.

Our media closet isn't exactly a walk in either, it's about 3' deep and 8' wide. I ventilated it this way because I didn't want to be moving a bunch of conditioned air outside the living space, but also because when I worked in IT I don't remember ever pulling hot air out of server rooms. Only pushing cooler air in.
Absolute
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AG
Another vote for Fife's suggestion. I would install a damper up in the attic at the splice, if possible, to turn off flow in the winter.
stridulent
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There is an air register about 8 ft away that puts air into a 2 story entry. To me, this would be an ideal location to dump the warm air as no one will be near it (warm air will stay at the top) and it'll quickly get sucked into the return that is nearby.

I do appreciate all the feedback so far. To me, this seems like the best option. Is it possible to splice it into the air register so that the register can exhaust the closet while still being hooked up to the HVAC?

Could use something like this maybe: http://www.homedepot.com/p/4-in-x-4-in-x-4-in-Wye-Y4X4X4/100396979
Absolute
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AG
Keep in mind that it is no longer allowed to simply exhaust building envelope air into the attic. Note that exhaust fans are supposed to vent to the exterior.

The perfect setup would be an inlet supply duct with a motorized damper wherever the duct splits off another line and a return vent tied directly into a return duct (with a motorized damper too, I suppose.) That would give you complete control and isolate the closet. In the winter you could turn off the supply but leave the return open.

Returning the hot air directly into the HVAC. If the heat is in the house, ultimately you pay to remove it. The amount of heat in the closet, mixed with other return air should be insignificant.
stridulent
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Absolute said:

Keep in mind that it is no longer allowed to simply exhaust building envelope air into the attic. Note that exhaust fans are supposed to vent to the exterior.

The perfect setup would be an inlet supply duct with a motorized damper wherever the duct splits off another line and a return vent tied directly into a return duct (with a motorized damper too, I suppose.) That would give you complete control and isolate the closet. In the winter you could turn off the supply but leave the return open.

Returning the hot air directly into the HVAC. If the heat is in the house, ultimately you pay to remove it. The amount of heat in the closet, mixed with other return air should be insignificant.

I agree, and I have no intention of exhausting directly to the attic. I worry about setting it up with an inlet and return because the closet is fairly small and the upstairs unit doesn't run very often, especially during fall, winter, and spring. I think the heat would build up to undesirable temperatures in these seasons.

What would be the concern of ventilating the heat to another area of the house? As you said, no matter what the heat generated by the components will have to be cooled by the unit. This to me seems to still be the best option.
Absolute
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AG
Sure, you could use some fans to vent the closet to the room. Maybe one as input (down low) and one as outlet (up high) with a thermostat control.
tgivaughn
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Since no one's living in that 25x25 room something simple to do would be to replace the door with a louvered door that breathes. You said it was close to the ceiling RA. When working on equipment, leave door open & use a box fan in the hallway to stay cool.

A handyman might simply cut that door to install vents T&B and avoid aesthetic critics.
Absolute
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AG
tgivaughn said:

Since no one's living in that 25x25 room something simple to do would be to replace the door with a louvered door that breathes. You said it was close to the ceiling RA. When working on equipment, leave door open & use a box fan in the hallway to stay cool.

A handyman might simply cut that door to install vents T&B and avoid aesthetic critics.
Would that actively cool the equipment well enough? RA vent will draw from the area of least resistance.
The Fife
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Louvered doors do a good job in our place at least with a coat closet about the size of what the OP is describing.

I was looking at their list of stuff again... if by A/V receivers they mean something like this with 600W power consumption each when switched on


then that's 1,800W when all 3 are on.

If the network server is an actual desktop PC or similar that'll be another 600W give or take. The rest of it either doesn't matter or won't be on much anyway, but realistically this is looking like a 25"x25" space with two bathroom heaters running. The room is small enough so that I can see how heat could build up way too fast for A/C which would be subject to that unit's on/off cycles.

I'll change my answer to a solution with two parts. The first part, I would install this at the top of the wall against where your equipment is to draw the hot air out of your closet where it will mix with the rest of the conditioned air in this part of your house. It moves 70cfm, or two air changes per minute your room and will need to be controlled by a high temp switch like an attic fan. The second part is to install a grille of roughly equal size near the bottom of the wall against your equipment stack for cool air to enter the closet. You'll need to add a little blocking or metal to close it off against the interior of the wall but that's no big deal.

If done this way, your house will still be sealed and not pulling unconditioned air from outside the building envelope, and your electronics should not overheat.
Absolute
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AG
The Fife said:

Louvered doors do a good job in our place at least with a coat closet about the size of what the OP is describing.

I was looking at their list of stuff again... if by A/V receivers they mean something like this with 600W power consumption each when switched on


then that's 1,800W when all 3 are on.

If the network server is an actual desktop PC or similar that'll be another 600W give or take. The rest of it either doesn't matter or won't be on much anyway, but realistically this is looking like a 25"x25" space with two bathroom heaters running. The room is small enough so that I can see how heat could build up way too fast for A/C which would be subject to that unit's on/off cycles.

I'll change my answer to a solution with two parts. The first part, I would install this at the top of the wall against where your equipment is to draw the hot air out of your closet where it will mix with the rest of the conditioned air in this part of your house. It moves 70cfm, or two air changes per minute your room and will need to be controlled by a high temp switch like an attic fan. The second part is to install a grille of roughly equal size near the bottom of the wall against your equipment stack for cool air to enter the closet. You'll need to add a little blocking or metal to close it off against the interior of the wall but that's no big deal.

If done this way, your house will still be sealed and not pulling unconditioned air from outside the building envelope, and your electronics should not overheat.


Seems like a great solution.
gansito
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This white paper does a great job helping you decide what's right for your situation:
http://www.apc.com/salestools/NRAN-6NDTJM/NRAN-6NDTJM_R1_EN.pdf

Fan-assisted ventilation is what TheFife suggested and the white paper agrees if the total wattage consumed is over 2000W. For my closet, i will be around that range and thus that's what I will be doing in my closet as well.
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