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Air to Water heat pump pipe layout

Here are my proposed piping layouts so far. They are missing quite a bit of detail like ball valves and such. I wanted to show the general thinking I am having for my system.

Currently, I have a gas boiler with cast iron radiators for heat and a standard ducted central a/c. My a/c is nearing it's end of life and I want to replace it all with an air to water heat pump to reduce my fossil fuel usage.

In the layouts, you will see that I am using the heat pump as a preheat for DHW. I will retain my gas boiler and indirect tank for DHW and as a central heating backup.

I have 3 heating zones and one cooling zone.


  • hot_rodhot_rod Member Posts: 13,509
    What is the hottest temperature you require? What is the purpose of MV 1?

    Piping the buffer as a 3 pipe would increase HP efficiency a bit, allowing system return directly to the HP or boiler.

    Here are the common piping arrangements for buffer tanks, subtle difference but definite advantages to 3 pipe.

    For 3 pipe, a tank with a large top connection is best. The buffer really only need to be involved when the load is gone, or smaller than the low end of the HP. Any other condition HP directly to load, no blending within the tank.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • hot_rodhot_rod Member Posts: 13,509

    I believe the issues are free if you registar.

    Volumes 4.5 & 6 are good reading with current piping technology.

    System 8 in the Solstice installation manual shows H&C, buffer, DHW and boiler backup.

    Notice how a single buffer with the boiler heating just the upper portion to assure DHW production.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • drooplugdrooplug Member Posts: 26
    I have looked at the Spacepak information. I have also read John Siegenthaler's book "Heating with Renewable Energy". That is where I am getting most of my information from.

    The 3 pipe buffer tank arrangement is interesting.

    The point of MV-1 is to reverse the flow to the buffer tank for cooling operation. That way the HP will supply the coldest water to the bottom of the tank. My goal is to stratify the buffer tank in both heating and cooling modes. I think having a 3 pipe buffer tank will preclude this from happening.

    I think the hottest temp I require is around 115F. I need to learn more about the heat pump I am considering and how much temperature loss I will have from the BPX.
  • drooplugdrooplug Member Posts: 26
    I was unable to locate the Solstice Extreme installation manual. I swear I've looked at it before.
  • RonnieJRonnieJ Member Posts: 41
    Energy Kinetics EK1
    SpacePak 3 ton Chiller
    Aircell Air Handlers
  • tim smithtim smith Member Posts: 2,317
    John Siegenthaler has one at his house he has been testing for appx 2 yrs. He is pretty impressed with it. Just for clarity, he is assessing it for mfr also. Total disclosure. I recommended one to a client and she had it installed, I could not get to it. Just up and running in last couple weeks. Will see.
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