GSHP vs. Wood Boiler

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I thought the DSH would only create usable "warm" water when the heat pump is running in cooling mode - am I wrong? We don't have much need for AC in Central NY, and the 1 or 2 weeks we might need it we would probably use the mini-split or a window AC unit, so I thought the DSH would be of dubious value. In my village house, I do already have a Marathon hot water with an add-on Geyser HPWH - I like it a lot for the dehumidification of the basement. So I'll definitely be doing this in the new place - it's just a question as to whether I pre-heat through my large 500+ gallon buffer tank or through something else..
If the geo runs for a long time and their is no need for hot water, it will make water up to 130F and then shutdown the DSH.

It will make a decent amount of hot water in the winter also. In the winter, you are robbing heat from your system to make hot water. In the summer hot water is being made from waste heat that is being pushed back into the loop. So you are essentially "making it for free". Sometimes I will turn the DSH off in the winter but haven't ever noticed a change in heat output. The COP on my geo is 3.5, the COP on my HPHW is 2.5 so the geo is a little more efficient at making hot water.
 
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If the geo runs for a long time and their is no need for hot water, it will make water up to 130F and then shutdown the DSH.
Thanks for this clarification. If I go with a GSHP, I'm going to build a big non-pressurized storage tank. Then, I'll run a pre-heat coil for the hot water heater through the storage tank. That will do the same as a DSH but without the extra cost and complexity. And I like to use the HPWH in the summer for dehumidification.
 
Thanks for the Uponor link webfish - I know this company well. I'm wondering if the staple-up (underside) radiant heat is worth the bother. Does anybody have any experience with this? Something like this http://www.radiantec.com/retrofit/
 
Late to the party, but a couple of observations.

We are also in central NY, with a 3 ton Climatemaster water to air geo system installed in 2011.
  • Horizontal loop on ours...not an issue in colder climates, the installer just has to have enough pipe in the ground, correct depth, and proper soil type. We stay warm at -20 F (not without some aux heat use when 0 and below). The decision of going with ground loop vs bore holes is usually a result of area of land for the system, soil conditions, or installer preference and cost.
  • Aux heat use is not a dirty word. There's a trade-off between size of system and cost of install vs some extra electricity needed to maintain temp when it's really cold. You can burn the wood stove then, if you want, but we don't bother. People think I'm lying to them when I tell them how cheaply we heat our house now. When the system is using aux heat, it is still extracting most of the heat from the ground.
  • Cost of system...varies a lot. Ours was not unreasonable, by any means.
  • Most important is the installer. The ability of the installer to design and install the best system for your situation, will make or break the system. There are a lot of horror stories out there (ours is not one of them).
  • Air vs hydronic heat. Personal choice...We have air, which makes AC easier to accomplish in the summer. FWIW, the unit has a huge HEPA filter in it. I always felt it was working as a whole house air filter, as well.
  • On the wood boiler vs geo, all I can say, is you never know what may happen in the future. A bad back injury took me out of the wood cutting I used to do, so we put the geo in instead of staying with our oil furnace. If you stay with a wood system only, you're locked into the manual labor that it takes.
My 2 cents, but I'd do the geo system again in a heartbeat. One of the best improvements to our house that we've done.
 
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