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Old 12-17-12, 06:32 PM   #1381
randen
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Default DIY GSHP Control

The homemade GSHP for the shop needed some control. The two thermostats would call for heat for the shop area and/or the office in floor heat. The ground loop circulation pump and the infloor/air handler pump will start followed by the 10 min timer for the compressor to start. This is incase of a power drop-out that the compressor wouldn't restart with head pressure. The zone valves will open as per demand by the thermostat.
Made the control up old school with some small relays from old projects in keeping with the build it from recycled goodies. I tried to incorporate the solid state relays but for some reason they wouldn't function. Had to go back to a wound coil relay. Damm. The LEDs indicate which thermostat is calling for heat and which zone valve is open.
The thermostats are programable. Today Monday each came out of weekend set-back at 6:00am and warmed the shop to about 18Deg C and the office floor to 24Deg C so far so good. We'll have to wait and see what effect -24deg C nights will do.

Randen

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Old 12-17-12, 10:17 PM   #1382
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Quote:
Originally Posted by randen View Post
The homemade GSHP for the shop needed some control. The two thermostats would call for heat for the shop area and/or the office in floor heat. The ground loop circulation pump and the infloor/air handler pump will start followed by the 10 min timer for the compressor to start. This is incase of a power drop-out that the compressor wouldn't restart with head pressure. The zone valves will open as per demand by the thermostat.
Made the control up old school with some small relays from old projects in keeping with the build it from recycled goodies. I tried to incorporate the solid state relays but for some reason they wouldn't function. Had to go back to a wound coil relay. Damm. The LEDs indicate which thermostat is calling for heat and which zone valve is open.
The thermostats are programable. Today Monday each came out of weekend set-back at 6:00am and warmed the shop to about 18Deg C and the office floor to 24Deg C so far so good. We'll have to wait and see what effect -24deg C nights will do.

Randen
What did you use to provide signal to the SSR as mine are 24VAC for the trigger and yours is a VDC input. I just blew one 125A which failed to closed, which they are not supposed to do, because I didn't put the unit on a big heat sink. I knew better and still didn't do it. It caused 12kw of elecric elements to stay on and reach 108C in a 120 gal water tank. Off went the PRV.
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Old 12-18-12, 09:02 AM   #1383
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mikesolar

The trigger was 28vdc full bridge rectified but un-filtered. I had bought three one let the smoke out and I had tried the other with a filtered 14 vdc and no joy. I'll have to leave it for a nother time

Randen
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Old 12-18-12, 05:51 PM   #1384
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mikesolar

The trigger was 28vdc full bridge rectified but un-filtered. I had bought three one let the smoke out and I had tried the other with a filtered 14 vdc and no joy. I'll have to leave it for a nother time

Randen
How much current did you put through the control side? Most that I know if are limited to 7-8mA
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Old 01-06-13, 09:33 PM   #1385
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I am just starting here, but in go mode. I have my drilling rig nearly finished. Got a couple of 12,000btu a/c units to hack and practice on. I would like to use my system to heat and cool my house. Planning on a pump and dump for gs, and using a air coil in duct-work. I need some ideas. Loved reading all the informative research that was done here.
Has anyone figured out a way to switch the hx's from summer use to winter use(like Randons cross over valve) but with ball valves or something? I do have a milling machine and lathe, but limited skills and tooling. Is it possibly to do this in a simple manner? I have tried to draw it out on paper but with no simple answer. Thanks!
Joe
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Old 01-06-13, 11:32 PM   #1386
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Gentlemen:
I am new to this site and have been thinking on the idea of making my heat pump more efficient. I currently have a 4 year old heat pump that is rated at 15 seer. While I sit around in a semi state of boredom I am thinking about the sall stream running on the back edge of my yard, a meer 110 feet away.

My idea would be to purchase a water to refrigerant heat exchanger, bury a bunch of pex tubing in the stream bed and circulate some antifreeze through the pipe thusly increasing my heat pump efficiency. I would like to bury the pipe just below the stream bed surface. could i get enough temperature transfer to make this work? I want to mount the heat exchanger and pump beside the existing condenser outside. It is in full sun until12:00 midday then it is shaded. Would I need additional controls if this is feasible for low pressures, freezing etc?

Some information: I have a 3 ton unit, 1650 sq ft house. New 2 pane windows 12" insulation in attic, new insulated doors, most walls have been insulated to 3.5", brick exterior. The stream bed is mostly sand, my yard is mostly sand to a depth of 20 feet. I live in eastern NC. Since I have lived here the winter temp has never been below 20F. My standby heat rarely comes on. The stream flows continuously summer and winter.
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Old 01-07-13, 07:31 PM   #1387
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I'm in a rush at the moment, so just a brief note...

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...I am thinking about the sall stream running on the back edge of my yard, a meer 110 feet away...
This sounds like a very interesting idea. It is kind of a hybrid between ground source and water source.

The principle is sound. I think your problem will be to determine the amount of coil (probably PEX or HDPE) you will require in the bed of the stream.

You'll likely need less than is required for GSHP but more than is required for pond loops, if you have running water, it is possible that even less than what is required for pond loops would be required.

If you bury your pipe even a foot, you won't need anti-freeze. The fish in the stream will be glad to hear that.

-AC
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Old 01-07-13, 10:55 PM   #1388
randen
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jlaw

I would think a little research is needed here. Here in Canada streams can freeze up and at the same time the ground water 6' below is still 50 Deg F. You maybe subjected to large temperature swings with a stream running basically across the ground exposed to the elements. Deep ponds or rivers a different story. There maybe ice on the surface but deeper could be several degrees above the freezing level.

That being said a stream as you say is running continueously all year is better at 34 deg F than trying to get heat out of air via ASHP at 20 DegF But still your COP will not be consistantly good.

If your going to purchase a water to air heat-pump anyway and bring in an excavator to bury the tubing a foot below grade. I would suggest going the extra few feet and place your ground loop at the proper depth for your area and have all the benefits of the ground source heat pumps.

The new heat-pumps are so energy efficient with a good install you would be so pleased.
If your going to hack your own heat-pump the ground loop is an extremely important part of the system. The better the source of heat the better overall performance.

Randen
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Old 01-08-13, 02:02 AM   #1389
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Quote:
Originally Posted by randen View Post
... Here in Canada streams can freeze up and at the same time the ground water 6' below is still 50 Deg F. You maybe subjected to large temperature swings with a stream running basically across the ground exposed to the elements. Deep ponds or rivers a different story. There maybe ice on the surface but deeper could be several degrees above the freezing level...
A picture is worth 1000 words...



These are yearly average ground temps.

jlaw is between the 62 and 67 degree lines.

-AC
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Old 01-08-13, 11:10 AM   #1390
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As AChacker says I do live in that 62-67 degree area. I am about 1.5 west of the ocean. Sometimes we get 1 snowfall a year. The stream never ices even on the edges. I understand, mostly, the operation and function of the heat pump I don't understand completely the design issues involved with adding a water to refrigerant exchanger. How to calculate size, exactly where to cut into the condenser line, how much pipe would be needed, the effects it would have on my current system, etc. I am capable of doing the physical work such as cutting brazing, adding refrigerant, doing electrical, etc.

based on information I previously supplied I am looking for guidance from the smarter guys than me. Have a great day.

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