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  1. #1
    Join Date
    Dec 2009
    Posts
    10

    Ductless (multi-split) geothermal (GSHP) ?

    Historic house is three-story, 180-years-old, solid brick interior and exterior walls with installed (some badly) ducts. Low-R envelope and resulting high energy $ has driven us toward 9-ton, closed-loop geothermal solution.

    And unusual heating and cooling loads and difficulty of installing ductwork through brick walls -- especially to second floor -- make at least partial ductless multi-split from GSHP attractive. (Hydronics alone don't solve cooling need.)

    There are plenty of split GSHPs with conventional air handlers available, but seemingly no ductless GSHP systems. Is there a commercial solution? Or would one have to be customed engineered? Seems like some progressive company would have been onto this combination by now.

    TIA ... Marc

  2. #2
    Join Date
    Nov 2007
    Posts
    86
    The preferred solution is either Liquid-to-Water or DX-to-Water Geothermal Heat Pump(s) with Hydronic fan coils. This solution will satisfy both heating & cooling - without the need to install forced air ducts! Only (relatively) small holes will have to be made to pass ~1in. pipes (plus insulation).

    SR

  3. #3
    Join Date
    Dec 2009
    Posts
    10
    Quote Originally Posted by fsq4cw View Post
    The preferred solution is either Liquid-to-Water or DX-to-Water Geothermal Heat Pump(s) with Hydronic fan coils. This solution will satisfy both heating & cooling - without the need to install forced air ducts! Only (relatively) small holes will have to be made to pass ~1in. pipes (plus insulation).

    SR
    Thanks for the prompt reply.

    DX is not an option (I'm a hydrogeologist and that much refrigerant in the ground gives me the willies ...). A water well was drilled for open-loop but it failed to provide adequate volume for heat pump. [I'm also an optimist ;-) -- It will be re-purposed/salvaged for garden irrigation. ]

    One of the most problematic rooms already has a Trane heat-only console. Ridding the room of that eyesore was one of the anticipated benefits of the HVAC make-over. A hydronic valence was considered when the open-loop supply was anticipated. We have not re-visited that option. Suggestions?

    Also: Residential *high-efficiency* liquid-liquid GSHPs are hard to find. WaterFurnace's Synergy 3D has good efficiency (although less than Envision) but its liquid loop is heat-only (Why !!? )

    ... Marc

  4. #4
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    They make a hydronic heat and cool coil that looks and works like a ductless split system. They need water lines, drain, and electrical connection. No outside unit required with water to water GSHP.

  5. #5
    Join Date
    Dec 2009
    Posts
    10
    Quote Originally Posted by hult View Post
    Also: Residential *high-efficiency* liquid-liquid GSHPs are hard to find. WaterFurnace's Synergy 3D has good efficiency (although less than Envision) but its liquid loop is heat-only (Why !!? )
    Ground-loop efficiencies for Heat Controller's Comfort-Aire new HWW Series Water-to-Water Systems don't look so good once one realizes that they have the data for ground-water and ground-loop reversed ...

    http://www.heatcontroller.com/products/pdf/HC-HWW-B.pdf
    http://www.heatcontroller.com/produc...W%20models.pdf

    ... Marc

  6. #6
    Join Date
    Dec 2009
    Posts
    10
    Quote Originally Posted by teeball57 View Post
    They make a hydronic heat and cool coil that looks and works like a ductless split system. They need water lines, drain, and electrical connection. No outside unit required with water to water GSHP.
    And most of what I've seen are floor-mounted consoles that look straight out of a 1960's government office building .... Can you steer me to a low-sone, high-mounting, unit that has a hand-held remote and other features that characterize the current crop of split mini ductless?

    My original question remains: Are there any modern multi/mini-split that use geothermal/GSHP technology ?

    Thanks!! Marc

  7. #7
    Join Date
    Dec 2009
    Posts
    10
    Quote Originally Posted by hult View Post
    And most of what I've seen are floor-mounted consoles that look straight out of a 1960's government office building .... Can you steer me to a low-sone, high-mounting, unit that has a hand-held remote and other features that characterize the current crop of split mini ductless?
    Answering my own question:

    http://www.multiaqua.com/

    Any others?

    Thanks ... Marc

  8. #8
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    And most of what I've seen are floor-mounted consoles that look straight out of a 1960's government office building .... Can you steer me to a low-sone, high-mounting, unit that has a hand-held remote and other features that characterize the current crop of split mini ductless?

    I'm not referring to floor mount units....See Mr. Google> Multi aqua!

  9. #9
    Join Date
    May 2008
    Location
    Columbia,SC
    Posts
    56

    Water sourced mini-splits

    I have not found any water sourced mini-splits but the commercial versions of mini-splits labeled VRF or VRV (for variable refrigerant flow or volume) offer water sourced condensers. Look at the Mitsubishi City Multi as well as the Daikin VRV equipment. I'm sure competitors like Sanyo and LG probably offer them too. All I have found so far are available in 3 phase power only so none address the residential market where 3 phase power is rare.

    I would definitely like to see single phase water sourced mini-splits.

  10. #10
    Join Date
    Jun 2006
    Location
    Republic
    Posts
    16
    Hydronic fan coils--water to water unit would work.

  11. #11
    Join Date
    May 2008
    Location
    Columbia,SC
    Posts
    56
    I've always felt a water to water system would be more efficient - and theoretically it "should be" - but as I look at the efficiency (EER) of most water to water units none that I have found approach the 27 to 30 EER of the current water to air GSHP units.

    I posed the question as to "why" in a recent on-line seminar and the manufacturer's rep said they have to use commercially available tube in tube heat exchangers. I'm stunned by that answer. Surely it would make sense to spend more to custom fabricate larger heat exchangers considering the tremendous cost of the geothermal source!

    I've actually seen air to air systems with higher EER's (close to 20) at part load than some of the water to water GSHP's! How can we justify drilling geothermal loops to install a water to water GSHP with an EER of 17 if we can have an air to air system with an equal or better EER?

    And making matters "worse" the stated EER of the water to water units often does not include the water source pumping energy (never for open loop) and can't include the energy the fan coils use to ultimately distribute the cooled or heated air. All that energy is included in the EER of an air to air heat pump even though it may be lower than what we encounter in the real world application due to increased static pressures, etc.

  12. #12
    Join Date
    Nov 2007
    Posts
    86
    “I've actually seen air to air systems with higher EER's (close to 20) at part load than some of the water to water GSHP's!”

    The question is at what temperatures…

    “And making matters "worse" the stated EER of the water to water units often does not include the water source pumping energy (never for open loop) and can't include the energy the fan coils use to ultimately distribute the cooled or heated air.”

    COP of mono block Liquid-to-Air GSHPs do include loop pumps & blowers. However,your point is well taken.

    If you’d like to eliminate ground loop heat exchangers (within the GSHP, not the ground loops themselves) & pumps, look into DX GSHPs.

    SR

  13. #13
    Join Date
    Aug 2004
    Posts
    200
    aermec make nice fan coils (even ones that look like minisplits) as well as air to water heatpumps

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