Dxgshpwh (ground source heat pump water heater)

[NiHaoMike]

Originally Posted by AC_Hacker

I didn't realize you were reading this thread...

Are you going to build up one of these little puppies??

-AC

Not in the near future, though it does look very interesting for an ultra portable A/C.

I don't think there's much of a good reason to go that small for a heat pump water heater except maybe in an off grid home. Even then, a small window A/C compressor would only use around 330W in a well designed water heater, which is easily handled by any proper off grid setup.

[jeff5may]

The same firm that specializes in the tiny compressors also builds larger bldc units. These ones run off r600a (butane lighter fuel):
H Series Catalogue -
The soda can line runs off r134a, it is commonly used in cars. If I wanted to use a natural gas in one, butane fuel would work. To get a decent condensing temp, some propane might need to be blended in. For such a small rig, I would probably just stick with r134a.

You won't see me messing with any of these things anytime soon. Until the end products start showing up in the second hand stores and yard sales, they are out of my target price range. For the price of a new compressor and control, I'm confident that I could throw together a mini split.

[marx290]

Yeah, I wouldn't suppose a HPWH with a 150 watt compressor, is going to have much capacity for heating. The recovery time is going to be very long. Seems almost absurd to attempt it....almost. I'm probably nit attempting such a device either, but refrigerator or freezer is another matter! Rarely does anyone attempt homemade refrigeration! I suppose these appliances consume relatively small amounts of energy,compared to heat and air conditioning, so they get little attention.

Building a better refrigerator has been a plan of mine for some time now. Basing the system on direct current seems like a logical thing to do. The few DC refrigerators I'm aware of are very costly, and not very attractive.

[NiHaoMike]

There's the Shannon Liu Quadrature Drive that is basically a VFD for "single phase" compressors, but it never made it outside the realm of research. The main application is a cheap alternative to small 3 phase compressors. Maybe we should work on an open source clone...

[Redmohawk]

I have a a Chinese made 12/24v 80L fridge freezer that uses a compressor that cosmetically looks very similar to the coke can unit displayed. I managed to pick it up new for under $250 Aust . They are a little unreliable I hear after talking with a local fridge mech .

They don't fix them , just throw them out. I've been keen to get my hands on a dead one for some fun , seems from what I can gather the compressors are fine , its electronics fails due to water ingress that kills them. Driving the compressor with an off the shelf 3 phase "Brushless motor controller" should be no issue.

[jeff5may]

Originally Posted by Redmohawk

I have a a Chinese made 12/24v 80L fridge freezer that uses a compressor that cosmetically looks very similar to the coke can unit displayed. I managed to pick it up new for under $250 Aust . They are a little unreliable I hear after talking with a local fridge mech .

They don't fix them , just throw them out. I've been keen to get my hands on a dead one for some fun , seems from what I can gather the compressors are fine , its electronics fails due to water ingress that kills them. Driving the compressor with an off the shelf 3 phase "Brushless motor controller" should be no issue.

Someone needs to build a refrigerator water heater. No doubt about it. Something euro-sized, somewhat smaller than an American-market dishwasher or oven unit. Large enough for two kitchen sinks of hot water (maybe 10 gallons) and at least a pony keg of beer. Its uses would be limitless for bachelors everywhere. If it could make ice, that would be ultimate.

[MEMPHIS91]

UPDATE:
234kwh used in 2635 hours (110 days)
That is 2.12 kwh per day. My power company just went to the peak hour and % system..... So as of right now I have NO IDEA what my power cost.

I will be adding a small accumulator to the system soon just because I know my green house heat pump runs liquid for a few seconds, I'm sure this one does too. I am also going to go with R1270 and a slightly larger compressor. And when my power company finely releases its peak hours I will make a timer so it will not run during those times.

[jeff5may]

I dontt know if you are aware of this, but the mapp/pro gas in the yellow cylinder isn't actually pure propylene. A mixture of propyne 30%, propadiene 14%, propylene 43%, propane 7%, C4H10 (isobutane, butane) 6% might be more typical. The manufacturers decided to stick some other stuff in the can because the mixture boils off better at lower temperatures.

[MEMPHIS91]

I'm pretty sure that mixture of MAPP is no longer made. What I'm reading says that now it is some propane/butane and high percentage of propelyne. I read that when I started using it, but I could be wrong. The stuff for sure preforms better, it's just very expensive. Lol

[superlen]

Memphis,

Thanks for the great project & great write up!

Do you have any concerns about the refrigerant line directly in contact with potable water? (single walled) I see that there are not any connections made in that loop, just copper in/out so the chance for a leak is small. (Nifty way to connect it to the tank too as others have mentioned) I have a desuperheater project and my coaxial heat exhanger is only single walled so I had planned on connecting it through a side arm to effectively make it a double walled equivalent. Maybe overkill, but I already have the side arm.

Len