Calculating Heat Load for Server Cabinet

[Vicken]

Not sure if this is right place to post this, but here goes.

I would like to install an AC on a server cabinet located in my garage (installing a window unit is not an option), but I don't know how to calculate heatload. What I need to know is how many Btu's/hr this cabinet is generating.

Here's all the information I have

Desired Temperature: 78 F
MAX Temperatue inside cabinet. 97 F
MAX Temperature outside cabinet. 90 F

Cabinet Dimensions:
3 ft wide, 4 ft height and 5 ft depth

Wattage (calculated from APC):
UPS: 950W
Server: 236W
Hub: 60W

I was told 10% of the wattage is a good estimate of heat generated from the equipment so the equipment is wasting 124W as heat. If anyone has a different opinion I would like to hear it. So basically the question is, how do I calculate the heat load?

 

[ScottMac]

Convert the Watts into BTUs and match up an air conditioner.

The formulas for Watts--> BTUs:

BTU per hour - multiply Watts * 3.413
BTU per Minute - multiply Watts * 0.005689

If you want to cover all possibilities, figure the watts for the available power (i.e., 120V * 15 or 20 amps), then calculate the BTU from there.

Good Luck

Scott

 

[CycloWizard]

All the power your machine dissipates is converted to heat (where else could it go?), so I'm not sure where the 10% number comes from but I'm highly skeptical. The maximum heat generation is the maximum power output by your PSU. You could also try posting this in cases and cooling, but the guys there are full of misinformation, so take their advice with a grain of salt. 😛

 

[imported_Soldier]

I'd say your half right CycloWizard. Some of the Watts are doing work so they wont go to waste heat. Looking at it the other way though I seriously doubt the equipment in the cabinet is running at 90% efficency either so Vickens 10% rule is suspect. I believe typical efficency for electronics rarley goes past 75-80%. I tend to agree with Scott that by figuring for total available watts to the cabinet you would at worse case buy more cooling than you need. I'd recommend that route anyway since typical cabinets end up with more jammed into them before too long so you'd be saving a future cooling upgrade.

 

[CycloWizard]

Originally posted by: Soldier
I'd say your half right CycloWizard. Some of the Watts are doing work so they wont go to waste heat. Looking at it the other way though I seriously doubt the equipment in the cabinet is running at 90% efficency either so Vickens 10% rule is suspect. I believe typical efficency for electronics rarley goes past 75-80%. I tend to agree with Scott that by figuring for total available watts to the cabinet you would at worse case buy more cooling than you need. I'd recommend that route anyway since typical cabinets end up with more jammed into them before too long so you'd be saving a future cooling upgrade.

Doing work - like turning the fans and spinning drives? That's about the only work done in the cabinet as far as I know, and even that must be converted to heat.