Differential controller running too long

Discussion in 'Solar and Geothermal Water Heating Forum' started by joe smith 100, Aug 1, 2009.

  1. joe smith 100

    joe smith 100 New Member

    I'm circulating water to my solar collectors with a pump is rated at 3.1gpm at 1300rpm and the heai is transferred to a 82 solar hot water tank. The temp.coming from the collector is about 210 degrees F.,but the differential controller keeps running all day long even when I'm not home and not drawing water except later in the day when the sun is setting. The water temp. at the faucet runs approx. 200 degrees F. Would increasing the gpm and rpm through the collector drop the water temp.?THANK YOU
  2. yes

    that is some damn hot water...
    are you sure it is that hot???.

    Is this a glycol system or some sort of potable water type????
    is this some sort of home --made system,
    or soemthing professionally installed??

    My guess is you probably have a bad sensor at the waterheater or on the panels
    or possibly in the differential controller cause
    it should only come on enough to heat the water maybe to 140, not to
    allow it literally boil the water in the heater...

    it is not suppose to literally keep running till the system starts to boil,
    it is only supposed to get so hot in a normal safe range and then shut off..

    200 degree water at what facuets???
    You must be talking about the boiler drains on your solar system??

    You dont mean faucets in your home, correct?? That would be so hot that it
    would literally warp the washers in a Delta faucet...

    JOE you really, really need to be careful with something
    that is literally close to or at boiling..

    I suggest you shut it off for your safety and your family.
    at that temp it would only take a micro second to be going
    to the hospital for massive scald damage

    you need to call some professional out to look over this system before
    someone gets hurt....

    Last edited: Aug 2, 2009
  3. joe smith 100

    joe smith 100 New Member

    Additional info

    This system was installed professionally 26years ago , and this month both the potable solar water tank and collectors have been replaced.Both sensors are new and checked out. The reading was taken at the kitchen faucet and since then a Honeywell thermostatic mixing and diverting was installed and the entire house hot water system only gets 140degree water. The controller is working as it should ,as mentioned earlier because when the sun is setting the pump stops running and does not come back on until the next morning when the sun is heating the collectors.I still believe that it has some thing to do with not enough flow through the collectors but that is only my guess an not based on proof.I have been told that covering one of collectors would help.Any suggestions .THANK YOU
  4. get them to come back out

    If they installed it only a month ago,
    you need to get them to come back out asap...

    becasue that simply is not working correctly..

    actually 140 through the home is pretty hot....

    I assume it is a drain down water type system
    where the water only is pumped up to the panels when
    the sun comes out??...

    they got something ass-backwards...


  5. Alphacarina

    Alphacarina New Member

    Biloxi, MS
    You obviously have a blockage somewhere - If you had even 1 GPM of actual flow, you'd never see anywhere near 210 degrees at the collector. Do you have a flowmeter in the system? If not, I'd recommend adding one and a valve to adjust the flow would be a good idea too

    Are you producing as much hot water as you were back when the system was working correctly? I'll bet not

    By comparison, with my system which consists of a 4 by 10 foot high efficiency collector and 110 gallons of storage, I've never seen collector temps above about 175 degrees . . . . and I circulate at 1 1/4 GPM. My pump kicks on 75 to 100 times per day and runs about 75 seconds each time. My temperature/pressure relief valve opens at about 200 degrees - 210 is dangerously HOT for any system


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