Geothermal heating system and extreme temperatures.

[irvingj]

Dodge man, you could probably easily add some temp probes to your DHW lines, so you could see the heat gain. I had done that on my original system; pretty interesting to see.

techman, yeah, I still wish I had that condenser, but my old one was a one-off handmade unit by a couple of HVAC nerd-types. They did well, other than use some (IMHO) inferior parts. Once I swapped the inexpensive check valves (Gemline, I think, all 3) and the Singer expansion valve for Sporlan parts, it continued to run for over 25 years until the compressor finally died. Think I had to change one reversing valve too, IIRC, and the blower motor quit at around 20 years.

The only problem I'm having with the Water Furnace is that I think I'm right at the limit of my water loop; in our first winter, during a really cold spell (-20F), the heat pump ran continually until the water loop freeze-stat tripped -- and locked out. It's apparently a manual reset. Now, when it gets below +15 or so, I run my wood stove off & on to help out and give the heat pump a break, though I still burn only about 1.5 cords each winter. Don't want to wake up cold in the middle of the night with the heat pump off again!

Was talking with my brother yesterday (still owns an HVAC company), and learned that air-to-air heat pumps have in fact made significant progress in the past 30 years. Also ran across an interesting article about a REALLY tight house, which discusses these new split systems. Goodbye Radiant Floor | GreenBuildingAdvisor.com. Interesting reading. ijk

 

[buickanddeere]

As long as the inlet temp of the water to the evaporator is 45-50F, You are laughing . If it's an undersized closed loop system and it's starting to freeze the ground around the loops, efficiency is dropping fast.

 

[doxford jim]

Just a note to my earlier post. The high temperatures that I thought I was getting at the circulating pump to loop, was caused bt the pump failing. A few weeks after the post the circulating pump seized completely. After talking with the local Geo. company that installed my system, I swapped the roles of the two pumps (my system has two circ. pumps) one is primary and the second comes on only when auxiliary heat comes on (as I understand it). The pump that failed was the one that came on first - basically ran full time. I switched the wiring so that the second pump came on instead of the primary (which had seized).

I tried the unit out and the system ran fine. The unit was/is able to keep the 2,000+ sq.ft. home at 68F - 69F without any apparent problems. One leg of the loop (to loop line) runs cooler than the return line, but not enough to frost anything up. In fact the cooler line has a good sweat is all - which I understand is fine.

Last night the outside temperature was -27C or -14F and the unit kept the house temperature at the 68/69 level (which we find comfortable), with only the one circulating pump running. Could it be that my system is over engineered ? The second pump will get replaced as soon as is possible. Oh, and according to my house electric meter, 105 kWh electricity was used for that twenty four hour period. I don't know if that is excessive or not - we are an all electric house (lights, hot water, heating, clothes drier and stove).

Thanks

jim.