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gas furnace & heat pump

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harvey
harvey Member Posts: 153
in THE MAIN WALL
Is anyone using fossell fueled furnaces WITH heat pumps? The heat pump runs until 38* outdoor temp and then the furnace takes over. Little or no defrost cycle. Energy cost savings are impressive.

Comments

  • John H.
    John H. Member Posts: 38


    Have installed many dual fuel systems and have no problems. We are in the Chicago area. I would recomend them to any one as long as they are set up correctly.
  • Ted Inoue
    Ted Inoue Member Posts: 4


    yes.
    I had a geothermal installed last year in a house that had existing baseboard hot water. The geothermal is sized to provide heat down to ~15-20F so that it would be more propertly sized to the cooling load and run efficiently for the 95% usage. Baseboard gives backup heat and is used to even out temperature differentials you get from the forced air system. Overall, I'm very happy with this solution.
  • RianS
    RianS Member Posts: 104
    Dual fuel

    Have installed many systems like that with oil and gas. Installed 3 recently with 2-stage variable speed nat gas furnaces and 13SEER Heat Pumps. Heat pump is primary, first stage gas is auxilary. Outdoor t-stat turns heat pump off at 28 deg. then goes to gas only. One customer said the furnace rarely kicks on high fire. Great set-up for hot air.
  • Darin(in Michigan)
    Darin(in Michigan) Member Posts: 90
    Heat Pump+Gas

    I am curious about the secondary voltage wiring and how the ductwork between the heat pump and the furnace is arranged. Is there a manufacturer out there that still makes a "piggy back" style like Carrier had back in the 80's where the heat pump utilizes the furnace blower for air distribution? What brands do you use?
  • John Mills_5
    John Mills_5 Member Posts: 952
    Like cooling

    The HP coil sits in the supply air just like a standard A/C coil. Now days, most use a thermostat with outdoor thermistor to interface the heat pump and furnace so they don't both run at once. You tell the "stat" what temp to stop the heat pump. Some will bring on backup, like White-Rodgers 1F95-391, others won't like the Vision Pro TH8320. The W-R also handles 2 stage gas backup, the VP won't, you have to use the board's timer, a disadvantage.
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