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  1. #1
    Join Date
    Nov 2006
    Posts
    1
    I have a Westinghouse 93% efficient gas furnace with an outdoor air conditioning compressor. The A coil is above the furnace. I would like to change the outdoor compressor to a heat pump and use the gas furnace only as a back up heat source if the heat pump can't keep up. I live in San Jose, CA.

    I have a 7,500 watt photovoltaic system on my roof so all my electricity is free. I am trying to convert all of my gas appliances to electricity.

    Can I change the AC compressor to a heat pump? Can I use the same A coil? Will I need a special thermostat or other controls to make it work properly?

    Thanks in advanced.

    Vince

  2. #2
    Join Date
    Oct 2004
    Posts
    3,400
    Yes, you can have a gas furnace with a heat pump.
    Whether or not you can use the indoor coil would depend on the particular model coil you have.

    Heat pumps must have a matched indoor & outdoor unit. Just offhand, I would say, don't reuse the indoor coil.

    A local contractor could give more guidance.

    Mention "dual fuel" when you call.

    [Edited by Wild Leg on 11-02-2006 at 03:57 PM]

  3. #3
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    You cannot change your a/c compressor to a heatpump without extensive work. You can change your entire outdoor unit(condenser) to a heatpump, and have a matched indoor coil installed,as long a s the airflow's correct. A local contractor is better suited to show you your options.Different controls are used,unless you have a h/p stat(universal). Free electric, I don't blame you.
    If everything was always done "by the book"....the book would never change.

  4. #4
    Join Date
    Sep 2006
    Posts
    1,253
    So what does it cost to get 7,500 watts for free? Is this the new thin rubberized sheets that glue to the roof?

  5. #5
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,296
    Originally posted by mchild
    So what does it cost to get 7,500 watts for free? Is this the new thin rubberized sheets that glue to the roof?
    FREE is a rather loose term
    ALWAYS !
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  6. #6
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,903
    So what's your surplus power per day as it is?

    On cold days, heatpumps can suck a hell of a lot of juice; less than electric resistance heat, but a hell of a lot nevertheless.

    Photovolaic systems do not produce as much in the winter as you probably know; on the other hand, 7.5kw is huge. (I don't even want to think about how much that cost you - even a 1kw system is upwards of $10,000)

    Direct solar hot water is the preferred renewable heating source.


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