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Old 03-06-15, 10:52 AM   #1
Apprentice EcoRenovator
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Default Yet another window unit heater but with solar and questions!

Hello Folks -
I have benefited so much from your posts in laying out a combined solar & ground loop supplied hot water heater but as I get ready to braze it together I realize I have more questions than answers - I did the attached drawing to guide me and the questions kept coming! I am old enough to know I ain't gonna guess right on many of them!
Please keep in mind that I have no (zero) experience in Hvac plumbing other than from you guys and a little in hvac electrical aspects but am a good welder/mechanic/electrician and garage grade machinist.
I have a 80 gal elec water heater, 7500 btu R22 window shaker, new 1/2 ton txv valve 0.016 bore with ext equalizer tanks Ebay), a vac pump and gauges, some reclaimed r22 which may or may not be good, a start on the geo bore, and have pretty much finished the condenser.
The drawing attached is probably better than the following description.
The condenser is 5' of straight 1.5" copper tube with a 1.5 - 1 -3/4 reducing tee at each end, mounted vertically beside the water heater - it has a 3/4" straight copper tube running thru the center of the 1.5 tube that carries hot water from the solar panel tank (when its hot) and enters and leaves the 1.5" tube straight thru the tees at the top and bottom.
The high side refrig line comes from the compressor mounted on top of the water heater and is 1/4 tube which goes past a service tap (and maybe a high press/ high temp cutout?) then enters the side of the top condenser tee then is wrapped round and round and soldered to the central 3/4" tube and exits the side of the bottom tee over to the txv. The water heater water (from the existing tank drain fitting hole) also enters the side of the bottom condenser tee & passes by thermosiphon up the annular space between the 3/4 and 1.5" tubes over all the 1/4 twists and out the side of the upper tee over to the existing hot water out connection to the water heater.
The refrigerant goes out the bottom of the condenser to the txv then out in 3/8 tubing into the evaporator which is 1" copper tube also mounted vertically beside the water heater with the 3/8 line running 5' up the 1" tube thru a U at the top then back down to the bottom of the water heater where it exits the evaporator. The geo loop water goes into the 1" tube at the bottom where the 3/8 exits, then up the evap. thru the u back down and out the bottom of the 1" tube where the 3/8 enters and back to the geo loop. No fins etc, just 3/8 inside 1" copper.
The 3/8 low side line the goes up the side of the water heater vertically thru a sight glass and dryer/filter past a service tap and into the compressor.
There is an equalizer line from the high side down to the tvx and the tvx bulb is horizontally mounted on the 3/8 line where it exits the bottom of the 1" evap tubing. I wanted to run the 1" line from there thru another U and back to the top of the waterheater but only have 30" of bulb line from the txv.
OK, OK here's the questions - and please don't feel so limited if you see something else:

1. Is 7500 btu of compressor feeding r22 or propane thru about 20' of twisted 1/4 tubing (maybe a very little bit of flattening where I wound it round the 3/4 line) and a 1/2 ton tvx going to be good from a flow standpoint?

2. Is vertical mounting ok for the sight glass and filter?

3. Is low side service tap mounted before of after the sight glass and filter?

4. Do I need to purge this while I braze it up? I have some 15% silfos and could use some argon from my welding tank but have no nitrogen- is that ok? Would retaining the filter already on the compressor keep junk out of the comp and enable me to avoid the line flush while brazing? Is it ok to keep the old filter or replace it?

5. Does anyone know if 10' of 3/8 line w/no fins inside 1" of copper is going to be enough? Ground water here is about 55 degrees F

6. Is my math good? 1 gal/min water at 55* dropped to 40* = 15 Btu/min x 8 lbs/gal = 120 Btu/gal/min = 7200 Btu/gal/hr - so say 1.5 gal/min of geo water flow would be ok even with some antifreeze?

7. Should I reuse the rubber bumpers the compressor is sitting on to mount it on the top of the water heater - maybe sit it on some angle iron runs across the top of the heater top cover? and do I need "S" bends in the high and low lines where it attaches?

8. Thoughts on whether it will thermosiphon enough to keep ahead of a 7500 btu compressor? I looked at the T where the condenser water reenters the water heater tank and wondered whether outflow when someone was using water would stop the thermosiphon and thought about routing it back into the tank via into one of the unused taps at the top of the tank. There are 2 - one is used for the anode but I think the other is unused. I could also add it to the tap with the relief valve on the side near the top. And I can probaby hunt down a 5000 btu compressor.

9. I don't have a micron vacuum gauge - will my line set gauges tell me enough?

10. Any other glaring mishaps or even helpful hints?

Thanks guys!

Attached Files
File Type: pdf WaterHeaterThermoSiphonGeoAndSolar3-3-15.pdf (178.9 KB, 209 views)
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