Just surfed onto this forum. Looks like a lot of good info. Our family enjoyed the benefits of open loop geothermal (100% of heat, cool, DHW) for 40 years. I built the first unit since nobody sold them back then. Now we have moved west onto a mountain where good wells can not be obtained. The well serves our domestic requirements but will not support a geothermal. So this will be my first closed loop installation. I have a barrel of fuel grade methanol. Can I use it (20% in water) for circulant? Is inhibitor needed, essential? If so, where do I get it? Thanks, Km
We make sure the water is good, either truck it in or you can use rainwater. Then you usually don't need inhibitor in closed systems. Sometimes it is mixing in with Glycol. Methanol usually inhibits microbial growth anyway.
Mark, Thanks for the reply. As of yet, nothing's been installed in the loop. Three vertical 350 ft. bores were finished last week. They are in heavy, consolidated shale and granite. The loops are 1" sdr-11 HDPE, grouted with Hi thermal conductive grout. They are wet from 40 ft. down. To start with, I am installing a variable speed 3.5 ton. We are off grid so the geothermal will be run by solar. There is not enough solar January/February so we will be supplementing with wood. I am anticipating that the rest of the year we will be OK. We do need quite a bit of air conditioning here. I was going to put well water in the loop. I would have never suspected that water impurities were involved. As for water testing, we had it tested for coliform but I doubt that makes any difference here. The water seems to be good. It leaves no residue. What do we test for?
Mark knows more than most, from his problem solving with hydronics. You need to at a minimum do a mineral test, ph, and any other dissolved solids, or iron content for happiness down the road. Eric
I used to fill loops and systems, (I do a good bit of water to water work.) with the nearest garden hose, until I had a system grow brown snot in "city water". I now test all my water for systems before filling. Filling is easier than un-filling to add treatment. See if you can get a source for Furnox chemicals near you. They will test the water and tell you what and how much you need to have a trouble free system. Mark
I am reviving this old post to thank Mark Eric and Doc for their help. We have now in our 5th year with the system and it works great. The pick up loop is three 350 ft, 6" wells bored in mostly consolidated granite. They are grouted with Hi thermal conductivity grout. They are parallel connected to two 3.5 T heat pumps. One of the heat pumps is running at 60% speed via a VFD. We are in NW Washington State where the loop will run 57 deg F with no heat load. The lowest I have seen it is 49 deg. when it was 17 deg below 0. I originally filled the loop with well water. Our well water runs 260 ppm TDS with no Fe. I have no inhibitor nor anti-freeze in the system. The loop is all SS, and HDPE with brass fittings.
