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  • Solar Water heater problem.. advice needed.

    I just purchased a home that has a solar water heating system in it. I'm totally new to the system and want to learn, and unfortunately, fix it. A month ago it seemed to be working great.. I was getting water heated to about 180 I believe.. then I started hearing a click, click sound.. over and over from the differential controller (GL-30)... after a day or two of that I stopped hearing the clicking and assumed all was fine.. until I noticed my water was now at line temperature all the time. I also noticed that even when the GL-30 said my pump was on, it wasn't... first thought was that pump died.. but after a bit of work I determined the relay was dead (I hotwired the pump directly to power and heard/felt it come on).. SOOO.. I replaced the GL-30.. and, happily, when I saw the controller turn on the pump, the pump turned on! Sadly, after about an hour I noticed the temperature was not changing.. the pump was still running and very hot, but the water was not circulating from the tank up to the panels and back down..

    I have a Solaraide system (so says the sticker) with a grundfos 15-18up pump on it... I believe the system is a closed loop system using some sort of glycol or some such fluid? I drained a bit out of one of the faucets and, while clear and water like, it had a sweet smell to it..

    My question.. finally.. is this... Does this sound like a system that needs to be pressurized? The temperature gauge also shows a pressure reading (manual dial type gauge), so I assume so... I'm wondering if somehow the system lost necessary pressure to allow the fluid to move through it in a circuit? I have NO idea if this is how this works... if it is, and pressure is needed and I somehow lost that.. or that the pump needs to be primed or some such thing.. I can't figure out what I can do about it? Do I need to bite the bullet and pay somebody to come check it out, or is there something I might be able to do myself.

    Any advice or ideas would be GREATLY appreciated!!!

    So wanting to let the sun do the work instead of Southern California Edison...

    Thanks in advance!!!

  • #2
    First step, for me, would be to make sure that you have fluid at the pump instead of an air bubble that is preventing the pump from moving liquid.
    The next step would depend on the geometry of the system and where there are test cocks or bleeder valves that I could use to check circulation.
    It certainly sounds as if the circulation is blocked for some reason. The relay clicking is an indication of a problem in the temperature sensors or control loop, and even if the pump was not damaged by the rapid cycling it could certainly use up the effective life of the relay itself pretty quickly.

    Can you measure the current to the pump? (Clamp-on ammeter?). That will tell you whether it is working against a load (actually moving fluid against a pressure differential) or just spinning to no useful purpose and generating heat through the resistance of the motor. If the current is too high compared to the Full Load Amps (FLA) rating, then the pump has likely been damaged.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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    • #3
      I have a good multi-meter that I can use to check the current to the pump.. I assume I can just come off the terminals that feed the pump from the GL-30?

      When I turn off the pump I hear water (fluid) running back down the pipes.. almost as if the pump is pushing water part of the way up the line to the collectors, but just not getting it up and through and back down the other side.. My pressure / Temp gauge is on the return side and that is what is not showing any temperature rise or pressure..

      I was afraid to open any valves just in case the fluid needed to be closed (probably wrong term.. I was worried about air in the line, I guess.. and worried that if I pumped fluid out, then there wouldn't be enough to push back up?).

      But because of that nasty gravity thing.. I also worried that if I open anything while the pump is off, that I'll just drain the system.. I can't see how you replace or replenish the liquid in the line..

      If I get the multimeter on the terminals that run to the pump, what should I be seeing or looking for?

      Thanks again!

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      • #4
        Originally posted by Stuntman View Post
        I have a good multi-meter that I can use to check the current to the pump.. I assume I can just come off the terminals that feed the pump from the GL-30?

        When I turn off the pump I hear water (fluid) running back down the pipes.. almost as if the pump is pushing water part of the way up the line to the collectors, but just not getting it up and through and back down the other side.. My pressure / Temp gauge is on the return side and that is what is not showing any temperature rise or pressure..

        I was afraid to open any valves just in case the fluid needed to be closed (probably wrong term.. I was worried about air in the line, I guess.. and worried that if I pumped fluid out, then there wouldn't be enough to push back up?).

        But because of that nasty gravity thing.. I also worried that if I open anything while the pump is off, that I'll just drain the system.. I can't see how you replace or replenish the liquid in the line..

        If I get the multimeter on the terminals that run to the pump, what should I be seeing or looking for?

        Thanks again!
        Put the meter, set to an appropriate AC amp range (the motor is AC, yes?) in series with one lead to the motor and read the amps.
        Look at the specifications for the pump (online) and see what the FLA number is. Compare that to the current you read on the meter and come back to us with the results.
        NOTE!: If the meter has a separate lead configuration for high amp (like a separate hole for the + lead just for a 10A range) make sure that you configure both the leads and the range switch properly before turning the system on. Otherwise you will blow a fuse if you are lucky or blow up the meter in your face if you are not lucky!

        Your description of the liquid starting to flow and then stopping could either reflect a total obstruction in the pipes up around the collector (probably in the return) combined with an air bubble in the collector OR a low fluid level leading to the pump sucking air on the return side after it has pumped enough fluid into the collector.
        Filling the system may require the use of an external pump to force new fluid into the system, combined with a manual or automatic air bleed valve at the high point.
        Often you will see a small submersible pump sitting in a bucket of glycol solution as you refill. Or a pump with a suction hose pulling from bottles of mixture.
        SunnyBoy 3000 US, 18 BP Solar 175B panels.

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