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  1. #1
    Join Date
    Mar 2012
    Location
    Florida
    Posts
    11

    Duel circuit water source heat pump

    One of my building units is a 5-1/2 ton duel circuit Florida Heat Pump (FHP) HE Series which is about 1990 vintage. I'm getting strange readings from both circuits that are testing my troubleshooting abilities. First, here is what I found initially;
    208 volt, 3 ph system, compressor data plate RLA 10.3 amp, T-Stat is single stage and both circuits were wired to start on a cooling call with a time delay for starting circuit #2.

    Circuit #1 Compressor sweating and icing at suction line, suction pressure 30, head 150, suction line temperature 31 degrees, 7.5 amps draw, reversing valve activated.
    Circuit #2 Compressor dry, suction pressure 105, head 150, suction line temperature 62 degrees, 4.5 amps draw, reversing valve activated.

    My first thought was that circuit #1 was low on gas so I added some. As I added gas my suction pressure did not change, head only went up a little and suction line temp went down a little so I stopped adding. I watched the reading for a few minutes and then I pulled my can of gas off the gauges to go warm it up. When I came back, My suction had shot up to 95, head was at 350 and my suction line temp was up to about 60. So I checked my condenser water to be sure I had good flow, I did, and so I recovered enough gas to bring my suction down to 74, head to 225, suction line temp was about 46. The compressor was still sweating but because this unit is not compartmentalized (evap coils and fan are not in a separate compartment from the compressors and condenser coils), odd design, so it's kind of like trying to work on an automobile engine with the hood closed, I thought the sweating could be due to air flow from having the cover cracked where my hoses came out. My thought at this point was that I had an obstruction in the fixed metering and it had suddenly cleared (no TXVs on this unit).

    I decided to take a look at Circuit #2 and found the high suction, low head previously described. I pulled the plug on the reversing valve, heard it click, but it did not change my readings. I activated, deactivated the reversing valve a number of times to see If I could get a change and eventually got a couple of reactions in the gauge readings. A couple times the suction shot up higher and other times it dropped back to 95. There was little or no change in the head pressure.

    So, my thinking is that the reversing valve on circuit #2 is bad and I had an obstruction in the metering device of circuit #1.

    One thing that bugs me is that I have little or no superheat on circuit #1. I checked the operation of the reversing valve on this circuit and found that it was also not operating, it clicks but does not change the gauge readings. Could it be bleeding by and causing my lack of superheat?

    Seems odd to lose two reversing valves but perhaps Circuit #1 has been OOO for a while and because it was in the cooling position it went un-noticed.

    Your thoughts are appreciated as always.

  2. #2
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    You never mentioned anything about the water temps. Also a plugged metering device will get you a high superheat. I would recommend getting your thread moved over to the tech to tech forum.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  3. #3
    Join Date
    Mar 2012
    Location
    Florida
    Posts
    11
    Water temps are 78 - 85 normally. I do think there must have have been an obstruction on circuit 1 that cleared (I hope). I'm replacing the reversing valves this week and I'll clean the system out good during that job. I still get the feeling like I'm missing something. As for moving the thread, once I get a few more posts and apply for Pro I'll try the Tech to Tech forum. Thanks

  4. #4
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    967
    you might as well check the water flow rates while your going through everything. but it sounds like your on the right track

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