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Solar Collector not heating water effectively

  • 25-06-2020 4:56pm
    Registered Users Posts: 2


    Looking for advice on source of problem with solar water heating. Compared to previous years system is far less effective.

    Installed 2011 with 2x 18 tube collectors and worked ok until 2 years ago. Serviced last year in June (new glyco, pump checked, controlled checked) and worked again but struggled to increase water temperature (lower "TST" sensor) by more than 10 degrees even on sunniest days in June. previously temp increase would have been 30 to 40 degrees or more.

    Today for example, 21 deg high, full sun all day, following TST samples...

    15:23 - 37.9C
    10:24 - 30.4C
    09:13 - 27.8C

    Collector temp as expected rises to delta of +8 deg then pump is triggered and collector temp drops as expected until delta of +4 deg, pump stops, collector temp builds again, etc. with pump kicking in every 10/12 mins.

    Note: pressure ca. 2 bar.

    Appreciate any advice on steps to diagnose problem and address.


  • Registered Users Posts: 64,346 ✭✭✭✭unkel

    If it didn't perform well straight after the full service last year, something was not quite right. I would contact the company again and explain your situation. Of course you should have contacted them earlier, apologise for that, be nice and ask if they could come have a look. They might do it free of charge.

    For comparison, my system is similar size to yours and today (even though we used plenty of hot water - family of 5 with 3 teenage daughters) the whole 360l tank was heated to 60C top and bottom

    And welcome to :)

  • Registered Users Posts: 2 kissanee

    Thanks Unkel,

    I did contact them at the time, was asked to check various things, none of which helped diagnose the problem. System had not functioned at all prior to service. Pity they didn't check the system performance after the service but they limit checks and don't include checking the heating performance. In any case I'm back onto them again and they remember me and are advising.

    Latest theory is that multiple tubes are gone and need to be replaced... builder who installed them did not leave details so I'm now trying to identify what manufacturer, etc. to source replacement tubes.

    Anyone out there know who might have supplied 18 tube collectors back in 2011. Seems 18 is not a common number of tubes!

    Thanks for the welcome!

  • Registered Users Posts: 64,346 ✭✭✭✭unkel

    kissanee wrote: »
    Latest theory is that multiple tubes are gone and need to be replaced...

    Seems unlikely. Hopefully when the service guy calls out they will find what the issue is. Keep us updated!