Doing something useful with heat dissipated from your fridge compressor

[phorvati]

Hi, this might be more geared towards DIY tinkerers, but has anyone tried using a good quality heat exchanger and high side of the compressor to heat water for the shower? I was recenlty working on an old commercial espresso machine and was very impressed with the quaity of a copper boiler. It had a heat exchanger loop that heated the water for espresso.
Then i had a thought...
I still intend to keep the fan as the primary condesing element, but I would add the copper boiler before the condenser, and then cycle the water in the boiler as it got warm, into the 6gal waterheater tank.
Would the high side copper line be enough the heat the water in the copper boiler from espresso machine, its about 1/2 gal?
Petar

[Whimsical]

A refridgeration unit pumps a very small amout of heat and to heat 6 gal needs lots. Not worth the complication.

Mike

[Nordic cat]

For energy efficiency, you want to keep the condenser temperature as low as possible. The higher the temperature at the condenser, the higher the pressure is that the compressor needs to pump up against, the lower the efficiency of the system. It has to do with compression ratios. The lower the fridge temperature the lower the pressure is that the compressor has to "suck", so if there is a big difference between suction and discharge pressure, the amount of gas the compressor can move for each stroke goes down. In industrial systems they try to keep the ratio below around 1:8. If you know what refrigerant you have, you can look up the temperatures and correlated pressures to give you an idea of where you are. Or else post here, and I can do it for you

You need to go the other way, use a salt water cooled condenser if sailing in warmer climates especially.

Regards

Alan

[over40pirate]

I was on a 40 foot boat a fellow was building, and he had some very interesting inovations on the boat.
One of them was a clothes dryer, that used wasted heat from his refrigeration, to heat the drum. Not sure how well it worked, but was an interesting idea.
He had bought the bare hull, without a deck, and was almost done with the boat, when I met him.
Quite a project.

[malovich]

I think he is talking about putting the hot part of the refrigeration inside the hot water heater and then going out to the cooling part or whatever it is called. I've taken engineering thermodynamics and forget many of the terms, processes and whatnot.
You could also attach a peltier to the hot side of the refrigeration and add a heatsink with cool lake/ocean water flowing through, in this sense you could make electricity from the wasted heat.

[Josh H]

Originally Posted by malovich

... inside the hot water heater ...

Not that I have anything valuable to add but isn't it a cold water heater or just a water heater? If your already heating hot water doesn't that just defeat the purpose?

[phorvati]

Josh, water heaters are well insulated and can store the hot water. I want the hot, high side copper line exiting the danfoss compressor, to go through the heat exchanger, and heat the fresh water. The hot fresh water would go into the water heater for storage of hot water.
You could do the same with black hose on deck during the hot summer day. Then just feed the hose water into the water heater.
I am trying to avoid running the engine every day for hot water. I also don't have the kind of AC capability to heat the water.