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I have a small server room approx 7' x 12' with an A/C unit dedicated to this room that is positioned on of the short (7') sides and blows air across the room towards the other short (7') side.

The server room is set to temp of 69F but usually will only ever get down to around 70-71F (temp measured by the thermostat control panel on the wall).

I have two 1-wire temp. monitor gauges plugged into a linux box that graphs out measured temperatures. Right now the temp. monitor gauges hang on one of the long (12') sides and are positioned closely together.

I don't think this is ideal measurement and an accurate representation of the room's real temperatures and would like to fix this. Where is it best to position the temperature sensors in a room like this? I don't think hanging them from the drop-ceiling would work since then the A/C unit would blow cold air on them (skewing the measurements terribly).

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up vote 7 down vote accepted

It would seem to make most sense to measure the air temperature on the front of the racks, where air is drawn in from.

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wouldn't this mis-represent the room's temperature though? Since the suction of the intake fans would cause measured temps to be lower than they really are (do to chill-factor)? Similar problem to hanging from the drop-ceiling... – SnakeDoc Apr 15 '13 at 18:53
Well, but that is what you CARE for. THe exhaust will be hotter. Intake is the most relevant part. – TomTom Apr 15 '13 at 18:59
So if I'm understanding correctly, you are advising to not worry about ambient room temperature and instead focus on server intake temperature? I suppose hot exhaust will recirculate and either be cooled before intake again, or it will pool up in hot spots and effect overall room ambient temp... leading to intake temp rise. Is this logic correct? – SnakeDoc Apr 15 '13 at 19:08
@SnakeDoc - yep. In short, all that matters is the temperature of the intake air. – EEAA Apr 15 '13 at 20:38

I would recommend putting the temperature sensor on the very middle of the aisle on the front and on the top of the middle rack.

The top of the rack (in front) because hot air rises, and you want to see what the hottest intake air is going to be, not influenced by the cooler air down below. The middle of the aisle because again it's most indicative of the hottest area, least effected by the AC area.

Don't worry about 'chill factor' as that's a 'perception of the body to temperature' not an actual temperature change. 80 degrees is 80 degrees (Fahrenheit) no matter if it's sitting still or moving about a room. It may feel cooler when it's moving, but that's the body's perception not the actual data. (it's a perceived decrease.. not a real one)

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Try using one of AKCP's computer room temperature monitors called the sensorProbe2.

They have a bundle that costs around $295 and you get a free network monitoring software.

They have a how to here :

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