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Community and Q&A

Choosing an Air-to-Water Heat Pump

crain1 | Posted in Mechanicals on

Hello, I am Building a 2500sqft colonial in climate zone 5 (CT).

·        R49 Attic

·        R30 walls

I am looking for input on the heating and cooling systems.

I plan to keep all HVAC equipment and duct work in the conditioned space.

My plan is to use open web floor trusses for the second floor system and run all of the duct work in the interstitial space between the two floors which would allow me to maintain a vented roof/attic and use blown cellulose.

 Initially I was learning towards a 2 zone Mitsubishi hyper heat mini split ducted system, however we plan to run radiant floors throughout as well and wanted to avoid redundant systems and outdoor units.  I prefer the idea of using one heat pump for both heat and cooling.

 Therefore I have been looking into air to water heat pumps and running chilled water coil in the air handlers (1 per floor) possibly using a First Co hydronic air handler.  I have considered using the water coil for heating during the shoulder seasons.

I am planning to perform the install myself and I am looking for feedback from folks who have such a system and or who designed the systems.  I am looking for single entity to design the HVAC and Radiant system so that I do not end up with conflict Manual J calculations etc.

I have been investigating a few air source heat pumps including:

 ·     Taco System M

·       Enertec

·       Nordic

I attached a copy of the floor plan for the 1st & 2nd  floors.

Please let me know if you have any recommendations on equipment selection  (performance, reliability/maintenance & cost) or designers.

Thanks for your help!

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  1. paul_wiedefeld | | #1

    What’s your expectation for floor surface temperature?

    The equipment will be expensive and reliability is anyone’s guess, as it’s extremely uncommon in the US. Efficiency seems to trail air-to-air slightly, but might be comparable if you’re using low temperature water for floors. The Caleffi journals explain how to do it, I’d reach out to them for designer/installer recommendations.

    Spacepak is another manufacturer too!
    Here’s someone who has done it:

  2. BirchwoodBill | | #2

    Couple of things to consider:
    1. Who is going to fix things when they break?
    2. What type of emitters/ heat sinks are in use? Panel Rads, Warm board, ceiling panels?
    3. Are you going to micro zone the system, bedrooms at 67F and bathrooms at 72F?
    4. How well is house sealed? Do you need to run a dehumidifier and ERV?
    5. What is your definition of comfort? This is very subjective

    Healthy Heating is a good online resource if you want a comfort based design.

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