I installed a used FHP open loop

Discussion in 'Geothermal Heat Pump Testimonials' started by Tony Scarpelli, Dec 1, 2013.

  1. Tony Scarpelli

    Tony Scarpelli New Member

    Hello all,

    This is my first post. I am a remodel contractor and Spray Polyurethane Foam insulation installer.

    I remodeled my retirement home (out in the country a bit) and when I got the prices of propane gas these days I started researching zero energy homes. That led me to install spray foam insulation in the walls and attic and install a water sourced heat pump.

    I cheated a little bit in that I used the Climate master savings calculator for a rough estimate of change in manual J. The calculator seemed accurate for the previous state of size and insulation so I thought I would give it a try. It said that the best level of weatherization and insulation properties in a home of 1674 sqft would draw 18,000 btus a/c and 20,000 btus heat, in my area (Kansas zone 4). So without too fine of point on it, I feel we did as good of job insulating a home as could be done with 4.5" wall cavity fill open cell foam in the walls and 5.5" in the cathedral room and 7" in the attic and gables. R values are low R14 and R28 or so but the spray foam prevents nearly all unintended breathing or heat gain/loss so probably perform close to R30 walls and R50 ceiling. We sprayed 100% of the walls, ceilings or attic and only have about 12-13% windows and almost none on the north and east walls. We plan on using passive solar warming as well and I might eventually get around to active solar heating of water and hydroponic system for partial heat to augment my FHP.

    I had a 3 ton a/c and 50,000 btu furnace. Now Climate-master calculator is calling for less than half those loads with the new "best" insulation option. I had my doubts in the accuracy of it considering the gun shot way I did the manual j. Rather than ordering a new unit based on that I held off ordering until a HVAC professional could consult me with new measurements for both Manual J and check the ducts.

    As luck would have it a client of mine was switching his server room A/C over from a GT serious (EER 20) 2 ton FHP. They could not afford the city water bills to run it after the city had 3 consecutive rate increases. AC guy checked it out and felt it works. So with destiny providing a free and easy way for me to test this size out, my having to fix the ducts and run the water lines eventually anyway, most of the work had to be done either way. We installed it. I installed it myself with the help of an off duty mechanical laborer. We doubled up the mastic on the old ducts within the attic (even-though the attic is sprayed with foam making the attic a sealed or conditioned space). I wanted the heat or a/c to go where I direct it to. The change in CFM from about 1100 cfm to 800 cfm was an issue so I talked to the code enforcement and he recommended closing the supply vents half way first and then down sizing the vents or cutting off one of three vents into a 900' openroom to help increase the air flow.

    After spray foam insulating the house we still worked on it through last winter and summer drywalling, painting and such (before installing the FHP) so we had a chance to see how the insulation performed. We keep the house 60 d F with a 1200 watt ceramic heater and the heat gain of the south windows and no other heat other than bodies of our labor. We also kept it 72 d F all summer with a 5000 btu window air conditioner. Even the few days that got above 111 d F it maintained 72 d F(although I suspect the cinder-block structure and concrete slab floor helped keep it cool as we did not have the long weeks of heat we might see).

    I think my well guy might have steered me wrong a bit as we upgraded 35' water level well pump from 1/2hp 10gpm to a 3/4 hp 20 gpm pump and it is cycling on and off several times a minute. I am going to order the largest pressure tank I can find but I am wondering if I should go back to a 1/2hp 10-12 gpm pump. I am only allowing 3-4 gpm through the FHP and with a full freon charge we are getting 8-9 Degree difference in water temps in and out.

    I'd love any feedback others would like to offer or questions. I thought we would start with the open loop but I might switch later to a closed loop. We have sand for a few ft and clay for about 20' and then more sand and clay below that.
     
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    My gut feeling on the pump is that a 10 - 12 gpm pump can run quite easily (even continuously without harm) and should operate more economically than one rated at 20 gpm unless you have a real 15 gpm load. (You have your pump dealer go over the flow curve charts of the different pumps which reveals where a particular pump runs best) (I am assuming that your new pump is significantly larger)

    Geo heat pumps always need an optimum (i.e. large) sized bladder tank if the pump is to have cool off or rest time between cycles. Being submerged helps dissipate the heat. I get good results with a conventional 3/4 HP pump rated 10 - 12 gpm on a 2 ton geo system. My actual flows do NOT remotely approach 7 gallons per minute.

    I have actually clocked almost three minutes off depending on how flows are adjusted. Another option to research or consider is 3/4 HP variable speed. I run a recently replaced a conventional pump which probably will last another 7 or 8 years. But the next time I would go with variable speed because it should save a little more energy.
     
  3. Tony Scarpelli

    Tony Scarpelli New Member

    Yes, its about time to upgrade the pressure tank. It is a 10 year old 30 gallon tank and I think I am going to get the 86 gallon, largest they have at Home Depot. We have the room, its only $350 or so and I will live here a long time.
     
  4. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    It your going to live there a long time.... Don't buy the tank from HomeDepot. Buy a high quality tank from a supply house or driller contractor.
     
  5. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Consider a Franklin VFD drive and a very small bladder tank. Open loop geo systems typically require 5 or fewer psi water pressure, a fact lost upon many who specify pumps for these systems. Oversized / poorly selected as to curve pumps tend to eat up some, most or all of the energy savings derived from geo, which is a crying shame.
     

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