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AC_Hacker · 05-01-09, 12:41 PM

OK, so by now we have some idea how refrigeration works, we have located and purchased an AC unit, we have taken the cover off and inspected it to familiarize ourselves with it.

The next step is to consider what we might do with it. If we do this right, we should get a COP of 2 to 5. Since COP is energy in divided by energy out, it means that for every kilowatt-hr we put in, we can get out 2 to 5 kilowatt!

Or to look at this in BTU terms, we multiply the watts by 3.412 to get BTUs. This means that every kilowatt will give us between 6824 BTUs (1000 x 3.412 x 2) to 17060 BTU's (1000 x 3.412 x 5). This really makes this an interesting project.

So here are some possible considerations:

Hack 0:
No mods at all. Just stick it in a window and use it as it was intended to be used. After all, summer is coming on.

Hack 1:
Turn it around backwards, modify the controls a bit and use it as an air-source, window-mounted heat pump.

Hack 2:
Keep the both the air-to-air condenser coil and the air-to-air evaporator coil, but re-configure them so that they could be used in a home ventilating system, to remove heat from the stale exhaust air (using the evaporator coil), and to warm fresh, incoming air (using the condenser coil).

Hack 3:
Keep the evaporator coil but remove the condenser coil and in it's place, use a refrigerant-to-water heat exchanger. This would give us a device that would remove heat from the air (and also de-humidify the air at the same time) and put the heat into water to be used somehow. One possibility would be a water pre-heater similar to these units:

Save Energy Maine - Energy Efficient Heat Pumps. Save Money on Your Heating Bills
Airgenerate.com | Adaptive Energy Solutions
Geyser Product Overview - Energy efficient heat pump water heater from North Road Technologies

Another possibility is that we could run the water through a ground loop, which would greatly increase the efficiency of our AC unit.

Hack 4:
Keep the condenser coil but remove the evaporator coil and in it's place, use a refrigerant-to-water heat exchanger. This would give us a unit that would remove heat from a water filled ground-loop, and bring it indoors for house heat.

We could also use the water loop for a high efficiency water-jacketed refrigerator.

Hack 5:
Replace both of the air-to-air coils, instead using water-to-water. This would give us a small, cheap water-in-water-out heat pump.

For the refrigerant-to-water heat exchangers, they can get pretty expensive. However, I have found that if you shop really hard, you can get good deals on ebay:

Here:
heat exchanger, Business Industrial, eBay Motors items on eBay.com

And here:
plate heat exchanger, Home Garden, Business Industrial items on eBay.com

The size we'll need is pretty small. For instance, if we're using a 400 watt compressor, and estimate our performance to be COP=2 to COP=5, the heat exchanger's capacity will be between 2730 and 6824 BTU. If we use a 1000 watt compressor, the heat exchanger's capacity will be between 6824 and 17060 BTU.

So look hard, there are some great bargains to be had.

Later I'll show you how to make a heat exchanger, but some of these on ebay are so good and so cheap, that it may be cheaper to buy.

05-01-09, 12:41 PM	#41
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	What Can We Do With This Thing? OK, so by now we have some idea how refrigeration works, we have located and purchased an AC unit, we have taken the cover off and inspected it to familiarize ourselves with it. The next step is to consider what we might do with it. If we do this right, we should get a COP of 2 to 5. Since COP is energy in divided by energy out, it means that for every kilowatt-hr we put in, we can get out 2 to 5 kilowatt! Or to look at this in BTU terms, we multiply the watts by 3.412 to get BTUs. This means that every kilowatt will give us between 6824 BTUs (1000 x 3.412 x 2) to 17060 BTU's (1000 x 3.412 x 5). This really makes this an interesting project. So here are some possible considerations: Hack 0: No mods at all. Just stick it in a window and use it as it was intended to be used. After all, summer is coming on. Hack 1: Turn it around backwards, modify the controls a bit and use it as an air-source, window-mounted heat pump. Hack 2: Keep the both the air-to-air condenser coil and the air-to-air evaporator coil, but re-configure them so that they could be used in a home ventilating system, to remove heat from the stale exhaust air (using the evaporator coil), and to warm fresh, incoming air (using the condenser coil). Hack 3: Keep the evaporator coil but remove the condenser coil and in it's place, use a refrigerant-to-water heat exchanger. This would give us a device that would remove heat from the air (and also de-humidify the air at the same time) and put the heat into water to be used somehow. One possibility would be a water pre-heater similar to these units: Save Energy Maine - Energy Efficient Heat Pumps. Save Money on Your Heating Bills Airgenerate.com \| Adaptive Energy Solutions Geyser Product Overview - Energy efficient heat pump water heater from North Road Technologies Another possibility is that we could run the water through a ground loop, which would greatly increase the efficiency of our AC unit. Hack 4: Keep the condenser coil but remove the evaporator coil and in it's place, use a refrigerant-to-water heat exchanger. This would give us a unit that would remove heat from a water filled ground-loop, and bring it indoors for house heat. We could also use the water loop for a high efficiency water-jacketed refrigerator. Hack 5: Replace both of the air-to-air coils, instead using water-to-water. This would give us a small, cheap water-in-water-out heat pump. For the refrigerant-to-water heat exchangers, they can get pretty expensive. However, I have found that if you shop really hard, you can get good deals on ebay: Here: heat exchanger, Business Industrial, eBay Motors items on eBay.com And here: plate heat exchanger, Home Garden, Business Industrial items on eBay.com The size we'll need is pretty small. For instance, if we're using a 400 watt compressor, and estimate our performance to be COP=2 to COP=5, the heat exchanger's capacity will be between 2730 and 6824 BTU. If we use a 1000 watt compressor, the heat exchanger's capacity will be between 6824 and 17060 BTU. So look hard, there are some great bargains to be had. Later I'll show you how to make a heat exchanger, but some of these on ebay are so good and so cheap, that it may be cheaper to buy.