Low temperature baseboards with geothermal

Discussion in 'Geothermal Heat Pump Applications' started by Brad, Jun 8, 2018.

  1. Brad

    Brad New Member

    Based on Doc's comments about my desuperheater thread, and other aspects, I've started to rethink my geothermal setup.

    Considering my house currently uses hydronic baseboard heating (currently using an oil boiler) across all three floors (2nd story, 1st story, finished basement) and ducted central air (2nd story, 1st story), I'm now instead considering the Hydron Cruise Variable Speed Water-to-Water unit... anyone have any experience with these types of units? Per Doc's idea, this unit could also produce domestic hot water for us in addition to the heating and cooling. Seems like a truly all-in-one solution.

    We would put an air handler in the conditioned attic (ceiling close cell spray foamed) and use the existing ductwork for cooling. While the ductwork could be improved, we're in Massachusetts and cooling is definitely the less critical aspect of our climate control.

    I would replace all existing baseboards w/ low temperature baseboards. The Hydronic Heating Technologies Inc. Eco-Con caught my eye, but I see there are a number of other brands too. I'm sure I'll need to do some math on if I can do a one-to-one (i.e. linear foot match) swap out of the existing baseboards w/ the low temp ones. I expect this also depends on outputted water temperature and flow rate.

    All that said, does anyone have experience w/ low temp baseboards? If so, on average, do you find you need more or less linear feet of low-temp baseboards to cover the current heating load?

    This really seems to be a great solution for those who currently use hydronic heating w/ typical baseboards and want to go geothermal.

    Thanks for reading and cheers.
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

  3. Brad

    Brad New Member

    Hmmm. I guess with this unit, there's the possibility I don't even need to upgrade my baseboard radiators. I'll confirm how they run in the dead of winter w/ the water temp set to 140 to 150F. Given it is an oil boiler now, I expect the water temp is closer to 180F. I actually haven't even moved into the house yet (next week), hence my not having data from this past winter.

    Thank you for the reply.
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You might want to consider the "direct to Load piping", getting you 10F warmer water to the radiators.

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    Brad likes this.
  5. Brad

    Brad New Member

    Thanks again for your willingness to share your expertise.
    Last edited: Jun 11, 2018
  6. Brad

    Brad New Member

    Doc, given your favorable view of the Waterfurnace 7 Series, do you think the Hydron Cruise variable speed water-to-water system is a solid investment and ready for primetime? I remember you saying on another thread to focus on performance over saving some money upfront. Because of this, I'm thinking maybe I should try for the variable speed water-to-water system and upgrade the baseboards to low temp baseboards, instead of going with the Waterfurnace 504W11.

    The 504W11 would presumably allow me to keep the original baseboards, but I'd also need to buy an additional two tanks for domestic hot water, bring the total tanks needed for that system to three (compare that to one tank needed w/ the Hydron).

    On top of that, the Hydron Cruise (variable speed compressor) should run more efficiently than the Waterfurnace (single stage). I've seen some apprehension on variable speed compressors, both water-to-air and water-to-water... but this has only been theoretical concerns by contractors I've spoken with. However, the empirical evidence seems to suggest these systems do indeed work and work very well.
  7. ChrisJ

    ChrisJ Active Member Forum Leader

    I believe you still need a second tank for DHW, internal heat exchangers that will have water from the heat pump circulated through them.
  8. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Attached is a Optiheat with DHW. 2 tanks. Credit to John Manning at Phoenix Energy Supply for the drawings...

    Your question is a tough one. The Hydron is a new unit, and I like the water-water variable speed concept. But the problem is that it is a new unit, and it might be prone to bugs a mature unit does not have. Plus it is utterly expensive.
    In general lowering your water temp via higher efficiency baseboards is a good idea.

    Just don't know if all of this is very cost effective. You mind get their cheaper with a good outdoor reset.

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