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  1. #1

    trouble shooting lack of heat

    Ive had a local hvac tech maintaining my FHP units for about 5 years. Started using him when I began noticing increase power consumption. Over the last 5 years my power consumption has tripled.

    System description: I have 2 FHPs
    FHP Model -GT042-1VTN, SN CG090069D
    FHP MODEL - GT026-1CSN SN CG0990070D
    Both have cupro nickel cores, gt042 desuperheater but its never been used. System was installed in 1996 originally an open loop system but converted in 1999 to a closed loop. Loop consisists of 4 vertical loops 225 feet deep for a total of 900 ft loop. 2 Bell & Gossett PL 36 pumps for the gt042 and 1 the same for the gt026

    My problem seems to be with the gt042 although I have another problem with the gt026 (it slowly leaks Freon somewhere).

    My hvac tech now recommending a replacement plus replacing the existing pump system with a new flow center enclosed unit. I dont believe he did any real trouble shooting other than to check the Freon levels.

    Its now mid February in New Jersey with one of the coldest winters weve had. The system is running almost constantly and my loop temp is steady at 45 degrees. I have little knowledge of hvac but this indicates to me the system is not extracting heat. Ive measured the pipe temp going into the unit and out with maybe to 1 degree delta. It does produce some heat, the air coming out is in the low 80s. My understanding is it should be in the 90s.

    Ive reached out to the mfg and all I get is a list of distributers. I did contact one and he confirmed that what I saw was not right. He suggested it could be scaling in the heat exchanger.

    Im at my wits end with this system now and its costing me thousands of dollars in wasted power now.

    Is it possible there is a valve stuck? Does scaling sound correct with the cupro nickel core and a closed loop? Is there something else I should be checking?

  2. #2
    Join Date
    Jul 2007
    Location
    New Jersey
    Posts
    3,031
    Did the power increase when converting to closed loop?
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  3. #3
    Join Date
    Aug 2001
    Location
    forney texas
    Posts
    17,890
    You should get someone to check the water pressure. You do it with a gauge inserted in the peets plug located where the water enters and leaves the unit. Water Furnace sell the gauge. After verifying the water pressure, have someone hook up a flush cart and flush as much scale and dirt out of the system as possible, then add water as needed. If I remember correctly , the water pressure should be at least 25 psi in cooling and higher in heat. You should have a specifications book that came with the FHP

    Does your system have heat strips for back up heat. Are they coming on.

    Resistance heat and rate increases by the power company should be the only reason your power consumption increases.

  4. #4
    When the loops were installed power did go up slightly. That was in 1999.

    Will check the presure (or have someone do it). The installation guide specifies for 40 degree water the suction pressure should be 45-50 and the discharge pressure sould be 192-200. I should also see a 6-7 degree drop. I'm thinking I might also have too much flow and was going to install a flow gauge.

    Yes it has 5KW heat strips that will basically run continually if I have them on. I've shut it off to save cost and because I installed a pellet stove and a gas fireplace for supplemental heat this year.

    Looking through the installation guide trouble shooting section it states to also check the reversing valve and TXV. I'm not sure how these are checked

  5. #5
    Join Date
    Aug 2001
    Location
    forney texas
    Posts
    17,890
    If the reversing valve was stuck, you'd either be getting hot air or cold air,

    unless it was partially stuck, then you'd see that with your gauges. If the

    TXV is blocked, the high side would try to pump down or you'd see Ice where

    the restriction is. You can also take the bulb off the suction line and heat it

    by holding it in your hand, making it open completely or throttle it down by

    putting it in Ice water. You verify by checking the sub cooling and monitoring

    the gauges.

    Before you do any of that you need to verify the water pressure is correct

    and flush the system. Here is a picture of a flush cart.

    http://ghpsystems.com/Equipment.htm

  6. #6
    Thanks all the quick response and advice. I had a new tech come today. system did not have the proper amount of freon even though the previous tech was here a couple weeks ago. Its possible it leaked but I doubt it as the unit was not producing any additional heat after he was looked at (plus he did not add freon). After the tech adjusted the levels the unit went from85 degrees to 97. I'll keep an eye on the temp delta between the air intake and output to ensure I'm maintaining the same increase, if not I'll have him back to look for leaks in the system. Thanks again, this was a costly problem!

  7. #7
    just wondering why you went from open to closed loop?
    If it was because of water quality than I hope they did an acid wash before hooking up the closed loop because a flush cart won't get all the build up out

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