Solar hot water fault

[Johntheo5]

I’ll monitor it closely tomorrow but I’m sure the pump constantly runs, the display only shows one temp which I believe is the AUX sensor (on instructions) which I think is the top of the hot water tank , I cannot see the collector temp other than manually read with multimeter, I’ve had it on just over 2hrs and it’s gained about 20° (started on about 15° it’s at 35° ish )
Cheers I’ll try that tomorrow to

Not sure what the 10 tube area is but probably around 1.7M2.
If you heated a full cylinder of water from 15C to 35C (unlikely?) then the tubes output was 140*10/860, 1.63kW, pretty good, and even if it only heated say 1/2 the cylinder, then output still 0.82kW.
You posted at 1413 hrs that the cylinder temp was 35C, did it subsequently rise further or was HW beig drawn off?.

You would want to keep a good eye on the tubes temperature while the pump is off, especially if very sunny, you don't want to thermally shock the system if the tubes get very hot which they (should) definitely will if pump left off for a hour, at 1.5bar pressure the saturation temperature (boiling point) of "water" is 128C so best keep well below that, suggest a max temp of 75C/80C and then re enable the pump.

 

[Johntheo5]

Carry out some tests today, pump off, reasonably sunny day with the odd cloud.

Collector top temps.
41C to 51C 1200/1205hrs 2.0C/min
51C to 59C 1205/1210hrs 1.6C/min
62C to 75C 1414/1421hrs 1.9C/min
75C to 84C 1421/1426hrs 1.8C/min
84C to 90C 1427/1433hrs 1.0C/min

Temperature increased from 41C to 90C, 49C in 27mins, average rise, 1.81C/min.

 

[Chris_909]

Okay thanks for the results, I think I’m gunna try putting a delay timer between the pump and controller, the controller never turns the pump off so I’ll use the timer to force the pump on and off, maybe 15mins on and 30mins off or something like like
Then I can see if the temp climbs