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Kingspan Solar Vacuum Tube hot water System troubleshooting

  • 29-06-2022 3:18pm
    Registered Users Posts: 21

    Hi, I have a Kingspan Vacuum Tube Solar hot water system, 60 tubes, with SC400 controller unit. I am having an intermittent problem that seems to occur when the sun gets really hot, or the rooftop temperature rises very fast. The system starts circulating properly, once the 8 degree temperature differential is reached, and the temperature of the sensor at the bottom of the hot water tank, starts to rise. However, the system seems to reach a point where the rooftop temperature rises too high or too fast, and the heat is not able to be transferred down to the tank fast enough, and the fluid stops circulating and I eventually get the flashing red Error 1 message. Even when I put the system into manual mode, to try to force the fluid to circulate, the Pump runs, but the flow rate is either zero or negligible. Only when the rooftop temperature falls below a certain point, does the system stabilise and starts to circulate again(once I have cleared the error message a few times). Anyone have any ideas what might be the issue please? I have played with some of the menus and settings but can't really see anything amiss.


  • Registered Users Posts: 3,489 ✭✭✭John.G

    Firstly ensure system pressure is ~ between 1.5bar & 2.5 bar. If so, its more than likely that you have air trapped in the collector tubes, you should also have a pump station with pump and temperature gauges, this may also incorporate a deaerator which is cylinderical and will have a venting (screwdriver slotted) screw, you can try venting here but more than likely that air will remain trapped above in the tubes.

  • Registered Users Posts: 21 david200

    Thanks John, I will check out those things tonight

  • Registered Users Posts: 21 david200

    Hi again John, I've been watching the performance of the system more closely in recent days. What is happening is that when the rooftop temperature rises, the system starts to circulate, but after a while as the reported incoming temp on the red side of the pumping station gets towards 80 degrees Celsius, air bubbles begin to become visible in the viewing window of the pumping station, and the build up and become more frequent, causing increasing momentary interuptions to the flow, and eventually causing the flow to stop, even though the pump keeps running. Eventually the rooftop temp on the controller unit goes up to 150 degrees and the whole system sits like that until later in the day when the rooftop temperature is lowered, then, after I clear the red flashing Er 1 message, the system starts to circulate once again. I'm trying to get someone to look at it in the next couple of weeks, but I wondered in the meantime if I might have too much water in the fluid, as it seems the air/gas builds up once the rooftop temp reaches around 100 degrees C, and the water is turning to steam maybe? Do you know what the right mix of Glycol/water is? Thanks

  • Registered Users Posts: 299 ✭✭spose

    Can you increase the pump speed to keep the tank temp closer to the panel temp

  • Registered Users Posts: 1,397 ✭✭✭dathi

    " if I might have too much water in the fluid, as it seems the air/gas builds up once the rooftop temp reaches around 100 degrees C, and the water is turning to steam maybe"

    no you have air in your system as the system heats up the gas expands and stops the flow. you need to remove the air and top up the fluid in your system

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  • Registered Users Posts: 21 david200

    Yes I think thats the problem. Either related to that or not, an additional issue is that the control unit seems to be slow to see the rooftop temperature going up. Could the air in the system be causing the rooftop temperature sensor to under-read the temperature? Just yesterday morning the control unit was reporting a rooftop temp of 30 degrees, but the incoming temp on the red gauge on the pump station was already over 60 degrees. So by the time the controller instructs the pump to start circulating, the fluid is too hot and won't circulate. I am able to enable the manual override and force the pump to run, early in the day, before the rooftop temp gets too high and long before the controller unit will tell the pump to run, and this works perfectly and is able to keep working away, slowly increasing the water temperature without any issue. The rooftop sensor was checked not too long ago and was working fine.

  • Registered Users Posts: 21 david200

    yes, by forcing the pump into manual mode, early in the day I can achieve that, and yesterday that worked successfully to the point where the temp at top and bottom of the water tank was 70 degrees

  • Registered Users Posts: 10,317 ✭✭✭✭tom1ie

    Folks are the solar water tubes worth it in your opinions?

    How do they operate in winter?

    How much do they cost?

  • Registered Users Posts: 1 liamo23

    Hi. I have what I assume is same system as topic of this post with Kingspan sc400 panel. I am wondering if anyone knows what issue could be as water is not heating and there is a knocking noise coming from panels on roof when sun shines. I recently got system serviced like glycol refilled etc but it's only since the summer has come that I realize there's this issue? I find it hard to get anyone who deals with repairs. Has anybody any ideas? Thanks so much.

    Kind regards