RE: Effects of heat on Servers

["Neil Ball" <neilball@xxxxxxx>]

One or two things to add, first the electrical plate load will give you
maximum power drawn by the equipment and not all of this will be given off
as heat therefore building in a greater or lesser margin depending on the
efficiency of the equipment you've installed. Secondly, the unit will only
be rated for a number of on/off cycles per hour, and may include timers to
prevent fast on/off cycling. If you oversize the unit too much then this
can
become an issue and lead to unstable room temperatures ie too hot then too
cool - this gets even worse with reversible units that can heat and cool as
they cycle between heating then off then cooling then off.....etc




> -----Original Message-----
> From: Johan Olde [mailto:johan.olde@xxxxxxx]
> Sent: Friday, September 05, 2003 10:34
> To: 'ukha_d@xxxxxxx'
> Subject: RE: [ukha_d] Effects of heat on Servers
>
>
> Kinda tricky isn't it?
>
>
> Assuming a room with a controlled temperature of say 18
> degrees. When adding one server giving drawing 300 watts and
> assuming all this is emitted as heat, would a 300 watt aircon
> do be enough to keep the temperature.
>
> If so, the calculations for the needed size of a aircon
> probably could be about the sum of all powersupplies rated
> consumption, which I guess should give a rather good margin
> to take everything else into account, even a added server or two.
>
> /Johan
>
>
>
> -----Original Message-----
> From: Paul Gale [mailto:groups@xxxxxxx]
> Sent: den 5 september 2003 10:30
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Effects of heat on Servers
>
>
> Mmm - not sure. If that extra 300W is heat energy being
> pumped into the room, wouldn't the Air Con unit have to work
> an extra 300W harder? Maybe false assumptions though
>
> Paul.
>
>
>
> -----Original Message-----
> From: Johan Olde [mailto:johan.olde@xxxxxxx]
> Sent: 05 September 2003 08:56
> To: 'ukha_d@xxxxxxx'
> Subject: RE: [ukha_d] Effects of heat on Servers
>
>
>
>
> While on the subject. I have a server room that is kept at 18
> degrees constantly by the aircon. I've been trying to find
> out the approximate energy cost when adding a server. If the
> server is using, say 300 watts, what would be the approximate
> energy consumption by the aircon to
> keep the temperature.
>
> I've asked a lot of people about this, but noone seems to be
> able to answer this in a believable way, which makes me
> wonder if it isn't that simple..
>
> /Johan
>
> -----Original Message-----
> From: Paul Gale [mailto:groups@xxxxxxx]
> Sent: den 2 september 2003 11:08
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Effects of heat on Servers
>
>
> Ok - now this gets complicated ;)
>
>
>
> What you basically need to do is work out the total heat gain
> to the room. This comes from heat from kit (obvious bit);
> heat from air getting into the room; heat through fabric of
> walls, floor, windows and ceiling.
>
>
>
> You first need to find roughly how much heat your kit is
> pumping out. This will be an estimate but the following
> figures may help:
>
>
>
> Standard monitor = 200 W/hr
>
> Server = 300-400 W/hr
>
>
>
> (of course depending on what your kit is - no of HDD's etc -
> this could be wildly different for you!)
>
>
>
> Add up all the kit then add:
>
>
>
> Lighting heat gains - for fluorescent lighting add 15W/hr per
> m2 of lighting
>
>
>
> Add:
>
>
>
> Air change heating effect - if you have ventilation such as
> extract fan etc
> -
>
>
>
> Air change in m3/sec x 1.2 x Temp Diff of air
> (inside/outside) = Watts/hr
>
>
>
> Air change is often calculated by knowing data on the fan (m3
> per sec or
> hour) and size of room in m3. An air change is defined as the
> number of times an hour that the total volume of air in the
> room gets replaced (either by sucking or blowing)
>
>
>
> OR If no forced ventilation, air still gets into the room
> through cracks etc at the rate of 0.5 - 1 Air changes per
> hour (called natural infiltration). To find the m3/sec value
> for natural infiltration to use in previous
> equation:
>
>
>
> (room volume m3 x air change) / 3600 = air flow in m3/sec
> where air
> change is 0.5 or 1 or so!
>
>
>
> Then ADD heat gain through walls, ceiling, glass, floor etc:
>
>
>
> Walls - total area m2 x 0.35 x temp difference = Watts
>
> Glass (double glazed) - total area m2 x 2.7 x temp difference = Watts
>
> Floor (solid concrete) - total area m2 x 0.6 x temp difference = Watts
>
> Roof - total area m2 x 0.35 x temp difference = Watts
>
>
>
> Add all these up. Temp difference is difference in
> temperature between the outside air/material and the inside
> air temp. You may need to guess this for floor and ceiling void etc!
>
>
>
> Then ADD:
>
>
>
> 100 W/hr for each person Permantently in the room (of part thereof!)
>
>
>
> ADD:
>
>
>
> Solar gains through windows - very difficult this one as it
> depends on whether there are blinds/curtains/glass
> treatments, time of year, angle of sun, log/lat etc. If you
> have a south facing window with no blinds etc - add at least
> 400-500 W/hr (could be grossly wrong though - depends on your
> situation!)
>
>
>
> You should then get a total heat gain figure for the room in
> Watts. ADD 10% or more for safety factor and this will then
> give some idea of the size of unit needed just to keep the
> temperature stable - add additional capacity to actually cool
> the room.
>
>
>
> As you can see, there are lots of factors - you may not
> actually want to do these calcs but it will give you some
> ammo to explain that it's not just the heat of kit that adds
> to the temp of the room.
>
>
>
> Hope this helps in some way!
>
> Paul.
>
>
>
> -----Original Message-----
> From: Rob Mouser [mailto:rmouser@xxxxxxx]
> Sent: 02 September 2003 09:32
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Effects of heat on Servers
>
>
>
> That would be fab! I don't mind signing the cheque just want
> to be sure
> 1) I'm justified 2) I buy the right thing!
>
> Many thanks
>
> Rob Mouser
>
>
> -----Original Message-----
> From: Paul Gale [mailto:groups@xxxxxxx]
> Sent: 02 September 2003 09:26
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Effects of heat on Servers
>
> 1200 BTU is VERY low for this kind of kit (did you mean
> 12,000 BTU???). Probably best to do the calcs in kW though -
> I recently had a 4kW air con unit installed in my office as
> the window is South facing and I have probably the same
> amount of heat generating kit in there.
>
>
>
> If you like, I can get the calculation data from my Father
> (who designs industrial AirCon systems) and let you know?
>
> Paul.
>
>
>
> -----Original Message-----
> From: Rob Mouser [mailto:rmouser@xxxxxxx]
> Sent: 02 September 2003 08:44
> To: ukha_d@xxxxxxx
> Subject: [ukha_d] Effects of heat on Servers
>
>
>
> This one is slightly OT, sorry.
>
> A little while back we moved to some new offices. Our servers
> are now located in a small room (6'x4'). In that room we've
> got 2 racks. Pretty much populated with:
>
> 5 Servers
>
> 1 Voice Mail PC
>
> 8u of IP Phone Switch
>
> 2 x HP Procurve Switches#
>
> A couple of large UPS's
>
> Routers etc etc etc.
>
>
>
> We've got a 1200 BTU aircon unit vented to the outside but
> its still getting pretty warm in there. A certain member of
> our office is arguing the cost of additional aircon as 'it
> will soon be winter'. I feel CERTAIN that this heat is not
> good for the servers but I need to back it up with hard
> facts. JUST TO PROVE A POINT ( I don't bare grudges
> honest!) Can anyone confirm the effects of heat on servers?
> Even better is their any web sources of info on the subject?
> Are there any calculations for BTU's required per piece of equipment?
>
>
>
> Many thanks in advance.
>
>
>
> Rob
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
>
>
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