Discussion in 'Maintenance and Troubleshooting' started by BatocheBob, Nov 12, 2012.

  1. BatocheBob

    BatocheBob Member

    I recently built a new house and installed geothermal heat. I tried to do everything right, used an ICF foundation, Walltite Eco sprayed in 2x6 walls and over the entire roofdeck and rim joists and used triple glass with two gas layers for windows. The geothermal pumps and ground loops were designed by one of the most reputable dealers in the area. Since they did not do any of the hydronics or air ducting one of the bigger and more reputable plumbing shops in the area built my control board and designed the floor loops. A local shop installed the air ducts.

    The winter heating season has just barely begun and I am finding my power bill for the past month is $300. It is calculated that the house itself is consuming about $130 worth of power which leaves about $170 to run the heating system. $170 strikes me as kinda high even for a conventional heat system and especially for geothermal. The system is keeping the house quite warm but is running in excess of 50% of the time. What I am noticing is that I have a 20 degree drop across my floor manifolds (in 95, out 75). I've had suggestions that the temp drop is two great to be efficient and the power company has suggested that sometimes these systems are wired wrong and consume excessive energy.

    I would appreciate any tips on troubleshooting, if in fact things are as wrong as they seem to me. The system consists of a 3 ton water-to-air system and 4 tons of water-to-water with 5 hydronic zones, only three of which are in production at this time. Thanks.
  2. Bergy

    Bergy Member Industry Professional Forum Leader

    Does your water to air unit have strip heaters? If so, they might be wired wrong allowing them to run when not needed. If your contractors are not familiar with heat pumps they might have the strip heaters wired to come on with a call for heat.

  3. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Couple of questions

    Size of house?
    Size of geo system?

    These give us an idea as to what you should be looking at for a bill.

    Do you have any circulating pumps running full time? Are they fixed speed?

    And then the bill questions. If I got a question like that for my local, my first question would be an actual usage bill? Or an estimate based on previous usage?
  4. Howard Ek

    Howard Ek Member

    Make sure your floor insulation is in properly!!! On the rim joists, I would recommend spray-on insulation.
  5. ChrisJ

    ChrisJ Active Member Forum Leader

    I have a radiant slab basement, my delta T is about the same as yours: supply 90*F, return 65*-70*. I am only heating the basement area to 65*F and I have a zone for the garage that I heat to 58*.

    How much under slab and perimeter insulation?

    The first year I started it up in November, it doubled my electric bill, but now I was heating 3800sq' not just 1900sq'. Now I start sending warm water to the floor before the cold weather really sets in.


    In the above thread it was discovered you only had a 2 stage thermostat for your water to air unit, Did you get one that has aux use available?

    Last edited: Nov 16, 2012
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Delta T of 20-25F is quite high, indicating very low flow rates. Geosystems should not have more than 10F, I prefer less than 7-8F. You circulation pump may be too small, or more likely, your zone valves have too high of a CV.
  7. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    If you told me you had 1000SF house and 8 cent kwh electricity in Dallas I'd be concerned. If you have a 5,000 SF house and 14 cent kwh electricity in Maine, maybe not that's darned good to heat for $170.00.

    Until you answer these questions (already asked) none of us knows if your bill is great or stinks.
  8. BatocheBob

    BatocheBob Member

    Sorry for the delay in acknowledging the responses. I usually receive notification but it didn't work this time. Starting from the top; The auxia\lary heat is not powered up; the heated area is about 4200 sq. ft.. My location is North Saskatchewan and I have 3 tons of water to air and 4 tons of water-water. There is a total of 10 circulating pumps. 3 on the ground loops, 2 on the buffer tank and 5 zone valves. Most of these are Stratos Eco & Wylo Star pumps; The floor has 2" of rigid foam, the basement is ICF and the rest of the house, including the rim joists, is Walltite Eco.

    I have contacted the power company but they are no help. Having said all this I have taken to monitoring my consumption. I checked after 5 days and I had consumed over 1400 kwh. I then took to monitoring on a daily basis and although nothing has changed, to the best of my knowledge, my most recent consumption is about 400 kwh for the past 5 days in spite of the weather getting colder. The one thing that still bothers me is the amount of time the system runs anywhere from 50% of the time up to 75% in this cold weather (-3C). If the power consumption stays where it is now I guess I'm not doing too bad considering the low temperature. Thanks
  9. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I still don't have a ton of information, but it looks like average temp in Jan for you is around -11C. If thats the case, and it's close to your design low (5 or so degrees) running 50-75% of the time.
    It really sounds like your expectations are the problem here, but again the information is scant.

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