Ventilating a server closet

Discussion in 'HVAC Heating & Cooling' started by beekerc, Mar 19, 2009.

  1. beekerc

    beekerc IT Consultant / Network Engineer

    Oct 9, 2008
    IT Consultant / Network Engineer
    Hi all,
    After having spent months in the electrical forum, now for a visit to HVAC. I have a server closet in my newly remodelled basement office. the picture is a cross section of the room, looking through the side wall. the closet is 3 feet wide. the reason for the two level ceiling and the header is that it used to be a wall. after the wall was roughed in, was i able to fire up some of my racked servers to discover that they make a lot of noise. so we ended up building a small pass-thru closet that extended into the laundry room (on the other side of the wall) and enclosed the server room. We used QuietRock and solid core, weatherstipped doors to isolate the sound which worked like a charm. turns out the header was a convenient place to put my patch panel to terminate all the wires coming throughout the house. the 110CFM ventilation fan (Nuton QTRN110) was installed before the wall was taken out. the air intake was put in near completion and connects, through a 5" flexible ducting, to a ceiling air grille in the laundry room, about 10 feet away to replenish the air that's sucked out by the fan. What I have found, is that because of the airflow through the server rack, the ventilation fan doesn't really suck out the hot air as effectively as i had thought. so here's some things i'm thinking about and some questions i have. figured i'd put it to those more experienced than I.

    1) the most effective location for fresh air intake is where the orange box is, low and in front of the rack. however, if i put two grilles so air just passes through the walls, it will let a lot of sound out. as such, i'll need to run some sort of ducting up through a stud bay, above the drop ceiling to a remote location air intake grille. do they make oblong ducts to fit inside a normal wall stud bay, or will i have to make due with 2" or 3" round pipes (and maybe more than one) in the stud bay?

    1A) instead of routing this to a remote location, just above the stud bay top plate, i'm not too far from the cold air return for the central HVAC. is there any problem if i just tap into the cold air return to supply air for the server room? it will suck air on demand just like the furnace does, and the air intake grilles are already in place. are there any code issues?

    2) the most effective location for the exhaust fan is where the current air intake is as it is right above where all the hot air accumulates. after i move it, should i just block the old fan hole, or would it serve any purpose to use it as a secondary air intake?

    3) the servers generate a lot of heat. i'd like to maybe duct the ventilation fan into the hot air ducts of my heating system (after all, i've already paid for the energy that generated the heat). does it violate any code if i have something else feeding the heater ducts other than the furnace?

    3A) but i don't want it feeding warm air into the house all the time. so here's a thought - let me know if this is feasible or not. i'd need some sort of duct valve that would allow me to divert the hot ventilated air into the heating ductwork or to exhaust outside the house. i would like to monitor the control signal traffic between the thermostat (a honeywell RTH7500) and when it is signalling the furnace to heat the house, have the ducting valve let the hot ventilated air go into the house. when the thermostat has the furnace turned off, or the air conditioner turned on, then divert the hot ventilated air to the outside. is this possible? does such a mechanical diverter duct valve exist? if so, is it very expensive?

    4) because of limited space above the ceiling area, i'll probably use an in-line fan, 120 to 150CMF, that way I can mount it anywhere above the drop ceiling as long as i can get ducting to it. any recommendation on good, reliable in-line fans? i've looked at Broan, Nutone and Panasonic so far.

    sorry for such a long post, i guess there's a lot of stuff to cover. advance for your advice, comments and suggestions.
  2. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    Inline fans...see Fantech.

    For 2X4 stud walls, they make 3 1/4" X 10" rectangular duct
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