Condensing unit BTU's

I found a place selling a used condensing unit for $120 that they say is rated at 12,000 BTU's. It is not listed as btuh (meaning btu's per hour) so I am wondering what this plain old btu rating is and how do you compare it to the amount of watts it can handle? I know that approximately 1,400 btuh is what's needed for one watt but the unit is not rated as btuh. Can anyone enlighten me?

Anyone know?

I think that even tho that unit is missing the 'h' in it's BTU measurement, it's understood that it's there.

As I understand it, BTU is a measure of heat over time- it doesn't mean anything unless it is coupled with a time variable.

A 12,000 BTU unit will transfer 12000 BTUs per hour if it is properly matched to an evaporator that was designed for it. Also, 12,000 BTU's is what is defined as one ton of air conditioning. In terms of cooling a CPU this is analogous to using a Howitzer to kill a mosquito.

One watt is equivalent to 3.14 BTU/HR. The maximum you would expect to see from the latest severly overclocked CPUs is probably no more than 75 watts (236 BTU/Hr). Since I work for an Electric Utility I certainly encourage you to proceed with this project (it will help my job security).

Also if you intend to use this unit you will need freon, a vacuum pump, soldering gear, a guage set and control circuitry. The evaporator will need an expansion valve or capillary tube. Other things like an accumulator/dryer and service valves will also be needed. How do you intend to build an evaporator that is matched to the unit and actually cool your CPU with it? In other words, the $120.00 might sound very seductive for that much energy transfer capibility but the practicality of actually utilizing it is zilch. The cost of constructing and operating it will many times pay for a dual processor machine with the fastest CPUs now available. Oh yeah, you will have to mount the condensing unit outside and run tubing to the condensing unit. It also probably needs a 220 volt 15 amp supply.

If these are used units and and have not been sealed, it is probable that internally they are in less than desireable condition. My suggestion is to stay away from it.

Just remember that it seems from ProjectX that the Evap should be 2x the condensor... That's lot of condensor...

Monster of Rock said:

As I understand it, BTU is a measure of heat over time- it doesn't mean anything unless it is coupled with a time variable.

Click to expand...

BTU is a measurement of energy. It is defined as the amount of energy required to raise the temperature of 1 lbm of water by 1 degree F.....The BTU/hr is implied, and this implication is fairly common if technically incorrect. When it comes down to it, the point is that 12000 BTU/hr is far too much overkill for a computer. I'm all for extremes, but a CPU can be cooled to far below freezing without going to these measures. Like RhoXS said, the support components to utilize the condenser to it's full capacity will cost far too much to make this a practical buy for this application. It's still a good deal on the condenser if it works, but it's not worth the money for this application.

The unit includes a compressor. Well, my idea was not for a direct die evaporator which would be small but rather to cool a tank of fluid to use as a subzero resevoir. I thought of getting a discarded chest freezer as the resevoir. It would be free and already insulated. This could acomodate a large evaporator. But if the rest of the components are expensive I do see your point.

just for future reference

about how much is a expansion valve?

evilted- so, the BTU measurement is like a calorie except in scale?

If that includes the compressor then it is a good deal... The evaporator can be made from simple copper tubing and the "expansion valve" while not very high tech can also be made by restricting the line some...

Monster of Rock said:

evilted- so, the BTU measurement is like a calorie except in scale?

Click to expand...

Yes, the BTU is the english measurement of heat energy, just as the calorie is a metric unit of heat energy.