The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by Vlad

During day time when heat demand is low and temperature outside is "high" you can gain some heat from air and transfer it to underground loop, increasing loop capacity. In my case I can add couple sun collectors on my roof, which has south exposure and during day time return line fluid before going back underground can go through sun collectors, gain heat and transfer it back to ground. At night when heat demand is high, you can extract this heat.

You are right, I hadn't counted the headers. Burying them at four feet is a very good idea...

I really like the heat reservoir idea too. Xringer has a point, if your loops are in an aquifer, the water will carry away the heat. On the other hand, if your loops are in an aquifer, the thermal transfer will be so high, and the fact that the aquifer will be refreshing the area around each loop with new warmth-bearing water, you may not need the solar boost...

However, if you decide to go with solar boost, be careful to not exceed the HDPE maximum temperature of 180 degrees. You would want at least a couple of sensors monitoring this condition, since the damage could be expensive.

It sounds like your weather and my weather are pretty much identical, with your temps being just a bit cooler.

On those freakish days when the sun come out and the sky is clear, solar collectors can really pump out some serious heat.

I have considered just such a setup with solar collectors and GSHP. It's not so unusual. The thing holding me back is that about 10 years ago, I put an aluminum shingle roof on my house, and they are not easy like composition to seal up.

I don't know what the situation is where you live, but here in the US, used flat plate solar collectors are practically being given away. In the 1970's there was a big push with government incentives, to go for solar water heat. Lots of people did it. The program was not as effective as it could have been, partly because the financial incentives were for the installation of the solar panels, not for the continued use of the panels. So after the initial pay-out from the government, there was little incentive to keep them working. Another thing is that the solar industry was very new and the "pioneers" who were the installers didn't grasp the importance of continuing customer support. The upshot is that the roofs that had the solar panels installed are now failing, and people are removing the panels and selling them very cheap, sometimes giving them away. I have ten panels in my back yard that I got for a total of $600. Because of my aluminum roof issue, I'm considering converting some of them to hydronic wall and ceiling radiators...they might even work under the floor.

Lastly, regarding the ASHP issue that you mentioned, the weather such as you and I have is actually very favorable to ASHP... The level of cold is easily within the working range of the equipment, and the heavy moisture content of the air increases the amount of available heat to be extracted, and yes it does freeze up on the coils, and there is a very effective and fast freeze sensor and defrost cycle built in (I believe the unit actually routes hot refrigerant through the frosted coils... it all happens in less than a minute). I think Xringer was indicating something about this.