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  1. #1
    Join Date
    Feb 2008
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    HeatController FP1/performance issue?

    I believe that our Heat Controller 5 ton GSHP forced air furnace is suffering from some emotional issues. The service guy has been here twice and has not done anything except call the factory help line and charge us a few hundred bucks to cut the FP1 and FP2 jumper. Both times I asked him to check the refrigerant levels and both times he "forgot his gauges"

    The FP1 cutout has been happening non-stop after the furnace being off for many weeks I turned it on for a cold evening and the furnace wouldnt stay running. I have tested the thermistor and it is good. Then magically it started going stints without tripping the lockout.

    The first 2 years we had this furnace NO PROBLEMS. This year the FP1 lockout has been going crazy... Tech cut FP1 jumper and problem went away for a few its back (even though its +40*<+80* outside and not -10*<40*??). NOTE: the entering water temp to the furnace has never been below 48* degrees and is above 50* 90+% of the time. and as I said the first 2 years we were fine at the 30* FP1 cutout and now all the sudden are tripping it at 10*????

    essentially when the furnace turns on I have these readings:
    FP1 = ~32*
    FP2 = ~71*
    LoopIn = 52*
    LoopOut = 51*
    ColdAirIn = 68*
    HotAirOut = 82*

    I installed probes on the FP1 and FP2 this weekend and real time data is available at: if anyone cares to look at real data or historical data. (note it displays ~40,000 points on the graph (which is zoom-able) so please use firefox or chrome to view... Internet Explorer will probably crash)

    Essentially I guess I dont understand how FP1 can consistently run at 32* with incoming water at 50* while only producing 13* worth of heat. Our electric bills and furnace run times have been climbing.

    P.S. the second stage (which never turned on the first 2 years) only adds about 2* to the output.... My calculations show the 5 ton furnace as putting out only a little over 2 tons.


  2. #2
    Join Date
    Feb 2008
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    Thread Starter
    Posted in wrong window... This should be in the HVAC directory but I cant seem to move/delete it!


  3. #3
    Join Date
    Jan 2004
    Sanborn, IA
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    without thinking too much about it i would be worried about your heat exchanger. your water as it is going through the unit is not dropping in temp at all. do you have a bacterial problem, or a hard water problem or other crap coating the heat exchanger which is in effect insulating the heat exchanger? i bet if he did put the gauges on he would be able to come up with a dirty heat exchanger.

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