I spent a year reading and learning about radiant heating systems and spent close to a year installing one in my house. Heat supply was from an outdoor wood-fired boiler. I hired a company to put in a Geothermal system for me and tied it into my existing system so I could use either as a heat source. So I tried the new geo system in October. During that month the incoming ground fluid temp dropped from 55 to 45 degrees - an alarming drop I'd say.I reverted to wood heat and the Geo system has been idle since. The pipes were supposed to be down 6ft but are at between 2 and 4 feet because of hardpan encountered during trenching. Pipes are NOT slinky. They're straight pipe, four per trench as I recall. There's about 600' of trench altogether. I thought from day one that the design was inadequate but was reassured by the contractor that it would deliver outstanding performance. The heat pump is a Carrier 4 ton. The contractor gave me no warranty on his work. What I'd like to do is have someone evaluate his design and if it's inadequate, force him to improve it. Right now he won't even return my calls. Any ideas how to proceed? How to get a second opinion on the design? Any help would be appreciated. Oh, I live 25 miles east of Seattle.

I am in Portland Oregon and might be able to help a little bit. I would need much more detailed information on your Trench and a full Manual J load calc numbers for your house to see what loop design i would expect. i don't work in Washington so i can give an unbiased opinion as there is nothing in it for me. However...

45 degrees EWT(Entering Water Temperatures) is fairly normal. If the ground is 55 degrees and you have not used your system then the EWT when you start the system is going to be in the 55 degree range, if you run the system for a month your going to be extracting heat from 55 degree ground, but as you extract heat the ground will slowly cool as well and may not only be at 50 degrees so you are only able to heat the piping to 45 degrees. Most systems are designed with freeze protection in mind so that means you could even get into the low 30 degree EWT range and still be operating normally for the Seattle area.

Personally I prefer straight pipes to slinky coils. According to my geolink design studio using 40K BTU heat loss for seattle WA with 4 pipe horizontal and an average depth of 3' I am showing you would need 475' of trench with a 4 ton hydronic unit in damp silt/clay soil with a 105 degree radiant floor. This is very approximate as I know nothing of your exact conditions. Besides the average depth of the trench everything seems normal.

Thanks Sky for your response. Yes, I see how the ground temp of 50 would show a lower temp on the incoming water temp. When I first fired it up, it was at 55 and stayed there for a while. The weather was pretty mild at the time. Later in the month the outdoor temp dropped quite a bit - maybe to 40 or so and the heat pump was running every time I checked. I know the efficiency drops as the incoming water temp drops and was extrapolating the temp at the end of heating season to be below freezing, at which point an air to water heat pump would have this setup beat, no? Anyhow, I appreciate your input and I'll press the contractor for particulars on the design - that may take a while - and post them for your opinion. I should say that the rest of my experience with this contractor was quite good. The work crew was fast, competent and very easy to work with. My only concern was with the design.

I assure you there are people here with much more experience in design than me so I hope somebody else will chime in and very or deny what I am saying but from the resources I have it doesn't seem perfect but also not to far out of wack either.