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Choosing between estimates for heat pump systems

LBrittBrattleboro | Posted in Mechanicals on

We live in Brattleboro VT and our 1300 sq ft house is far from air-tight but there is blown insulation in the attic and newish windows.

We are in the process of getting estimates for a ductless heat pump. We have 3 estimates.

Company #1:  suggested a single 30k btu split condenser with 1 wall mounted unit upstairs and another downstairs.

Company #2: suggested a single 24k btu split condenser with 1 wall mounted unit upstairs and another downstairs.

Company #3: suggested  2 separate systems, 1 condenser and wall unit for upstairs and 1 condenser and wall unit for downstairs. Each condenser would be 12k btu.  

To add to the confusion each suggested a different brand condenser.

So my question is which of the above plans makes the most sense and which brand of condenser is best for our situation.

Thank you,

Lindsey Britt


  1. user-2310254 | | #1


    Did any of the contractors provide you with a Manual J? The report will show how they calculated your home's load.

    Did any of the contractors suggest equipment that works well at low temperatures (Mitsubishi calls this Hyper Heat)?

    For a single-head or multi-head unit to work well, occupants typically need to keep doors open. If you close your bedroom doors while sleeping, you may encounter comfort issues. Did any of the contractors suggest installing a ducted heat pump?

    Last, it often a good idea to hire an independent HVAC designers to complete the Manual J. This person also spec the right equipment for delivering comfort with the lowest energy penalty. To learn more, see

    1. LBrittBrattleboro | | #2

      Thanks for the reply Steve. None of them mentioned preforming a Manual J calculation. All of them stated the equipment is rated to perform to -13f. None suggested ducted heat pumps.

  2. paul_wiedefeld | | #3

    Broadly, you want a system sized correctly for the heat load at design temperature (unless you have backup heat, which changes things). As capacity changes based on outdoor temperature, there's no way to know which, if any, of these options are sized correctly. Either 24kbtu might actually be higher capacity than the 30kbtu option, there's not way to know without looking at the spec sheet, which should show output at low temperatures.

    This heat loss method works great if you have historical fuel usage data.

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