Feedback on a proposed retrofit system

Discussion in 'General Discussions' started by GEK, Jun 13, 2008.

  1. GEK

    GEK New Member

    I'm working on a retrofit residential geothermal heat pump system and would appreciate feedback from those with more experience.

    The house is large, about 5500 sq feet, currently with two furnaces (oil - forced hot air). It is a 1978 wood frame construction. We're located in New Hampshire.

    The main furnace services about 4500 sq feet, with a second unit servicing a large room over a garage. The main furnace also has central air conditioning. Air conditioning is a low priority, we only need it for a few weeks every summer.

    The property has had several well shafts drilled because of low water flow. The proposed well to be used is a 1000ft shaft that was abandoned because of low flow. I pulled the cap and the current static is at 16'

    Design proposal is to replace the AC unit in the main furnace with a 5 ton system. We'll tackle the secondary furnace in the future as funds allow. Oil will remain as a supplementary heat source in the main furnace. Proposal for the well is to place a pump at 100ft with a return at 980 feet (Standing Column) with zero bleed.

    I realize that a 5 ton system can't meet the total heat load in winter. We currently use 6.5 tons of pellets and 1250 gallons of oil overall. I hope that it will substantially reduce the oil usage. I also plan to increase insulation, seal air ducts etc and we are in the process of replacing windows to reduce the heat load demands.

    The option of a desuperheater has also been discussed. I wonder if it would be worthwhile with our low AC usage and a somewhat undersized system?

    Any thoughts, ideas would be greatly appreciated!

    - Gary
  2. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Sounds like an interesting project. How is your hotwater heated now?
  3. GEK

    GEK New Member

    Hot water is a stand alone oil system.
  4. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    You could add the desuperheater and then turn it off if the unit was not keeping up with the heat load. Just be sure and add a preheat tank for the desuperheater.

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