Dxgshpwh (ground source heat pump water heater)

[MEMPHIS91]

Superlen, Thank you! Glad you enjoyed it!
I think double wall is going to hurt your heat transfer.
There is zero worry with the single walled pipe. 1/4" is some pretty tough stuff, and copper has been used to carry potable water for a very long time with no problems. It would be a pain to get anything bigger into the small size element hole.

Please let us know how your build goes!

[MEMPHIS91]

Update!
No problems at all!
5299 hrs running = 221 days
475 kwh = 2.15 kwh per day = less than 25 cents a day!!!

I will be adding the txv soon I believe.

[MEMPHIS91]

7632 hr = 318 days
Used 665 kwh of power. 2.1 kwh a day = 21 cents a day.
I haven't even check pressures since I built it.

[MEMPHIS91]

Alrighty, finally found time to start work on the long awaited update to the already amazing water heater. First round of business, prove WHY this was "needed".
This update will do the following.
Dehumidify my indoor air.
Cool my indoor air.
Save energy because the ground at 30' deep right now is only 55F, while my indoor air is 76-78F.
And 4th produce water to "flush" my dogs homemade liter pan. Yes you read that right.

So onto the build. First step was finding the right size coil. I thought it a good idea to go BIG, as in HUGE. First reason because everyone who has built one of these monsters has their coil freeze up, and reason two being that I want to use as small a fan as possible to save energy.
I selected an amazing trane 2 ton coil. Yes 2 ton.

Then I needed a drip pan. I just used the bottom of the unit I stole the coil from.

Next I used one of my large 110 cfm dc fans. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Added a drain tube and cut the supports.


Then the brazing began! First was the half ton TXV.


Then everything gets bolted together (glued/mold free silicone)

And lastly (for tonight) she get mounted to the wall.


I will have ball valves on both loops in order to control which loop for which season. Hence the need for the TXV, cap tubes need extremely fine tuned charge, while a TXV is sightly more forgiving. I would rather a little wasted power vs flooding my compressor with liquid propane.

More to come soon!

[jeff5may]

Nice! What a radical change! You can't say the air-cooled evap is too small compared to the dx loop...

However, I suspect you will be running into the same situation other dude is with your super-sized evaporator. To get a low enough SST, the fan may need to go SSSLLLLOWWWW if you need it to dehumidify.

[MEMPHIS91]

Thanks Jeff, yeah I thought about that. I can even cycle the fan on and off if I need to. But either way cold air will be made. I got the rest brazed this morning. And pulled a DWP vac, gonna fire her up when I get home.

[MEMPHIS91]

Well I finished up today. I don't have much data to post yet. And since i can only take outside tank temp the data will not look the same. What i can say is with an outside bottom of tank temp of 95F I had 66psi suction and 230psi discharge with 13F superheat and 11F subcooling. Compressor pulling 3.32 amps. So I might be just a little overcharged, but I will see what happens as things get hotter. (I had to take a shower so everything cooled back down)
I'm getting TONS of water and now my laundry room is the coolest room in the house.
I'll post more data soon.

[MEMPHIS91]

Info: This trane coil HOLDS water, so most of the water doesn't run off til AFTER the unit shuts off. I already have a timer to let it run doing the hottest time of the day (noon-7).
Question: Should I also have it run for 45 minutes and shut off for 15 minutes to aid in dehumification?

[jeff5may]

The water in the spines actually helps transfer heat better. Much research has been done on the subject of spiny pipe versus tubes and fins. Main ideas: spiny pipe costs the least to make, has slightly lower efficiency than tube and fin, and is harder to clean. Easy to flush, though. Dehumidification factor is the same. Parallel micro-channel and fin designs beat them both by a substantial margin, but cleaning and flushing them is much more difficult. Automakers have pretty much all switched to micro-channel condenser coils, so a contamination event pretty much necessitates a new condenser coil.

At 66PSIG, you are pretty close to freezing your coil. I try to keep mine above 60 during trials, as frozen things happen around 55. That's with propane. If you are running propylene, this happens around 70. Blend is somewhere in between.

Preliminary numbers look pretty darn good to me.

[MEMPHIS91]

I can tell how much the water on the coils help. I only used 1.2kwh of power today heating my water 4F HOTTER than the dx coil that was using 2.1kwh.

Parallel micro-channel coils.............. hhhmmmm, you say these can handle the pressures of a phase changing monster? Because I have 4 nice size coils that are not be used YET. I guess I always though they were only for water/low pressure.

So I think leaving the fan going the entire time is the best way. I'll continue to let my dehumidifier do the most moisture sucking til the geothermal unit can run as less capacity for longer times to take care of it.