Hot water temperature.

_Brian

We have solar thermal and solar PV with Eddie, eddi dissent need to heat hot water today but I noticed the thermal brought the water temperature to 71c, measured mid way on the tank, it’s 7ft tall tank don’t remember the volume.

What’s the usual temperature that’s enough and stop the thermal heating the water ??

graememk

https://www.boards.ie/discussion/2058351147/hot-water-temperature

Solar thermal tanks usually have a thermostatic mixer valve on the outflow to mix the tank down.(To make 70+c water safe)

If thermal solar is heating the tank, it's the whole tank.

I think there is a setting in the controller that would limit the temperature of the tank.

John.G

The sky's the limit if the HW demand is very low. I have flat plates and mine reached 78C today but I have the max cylinder temp set to 85C (on solar only) with a anti scald TMV on the cylinder outlet set to 60C, this high cylinder setting ensures that the solar circ pump keeps running and consequently the plates never reach stagnation temperature to cause premature degradation of the solar fluid, I have never changed mine in 13 years since installation. Evacuated tubes can reach > 250C during stagnation and should really have a heat dump installed but rarely do.

_Brian

https://www.boards.ie/discussion/comment/122121995#Comment_122121995

https://www.boards.ie/discussion/comment/122122016#Comment_122122016

Ours are flat plate not tube. In 14 years.
so 70’s isn’t excessive or dangerous?

John.G

Not dangerous/damaging to the solar system but obviously can result in scalding if no antiscald valve installed. There is a setting in the solar controller "max cylinder temperature" or words to that effect which then stops the solar circ pump at whatever its set to, the plates can reach temperatures of > 130/150C but this may may be lower dur to degradation over the years. What is the make/model of the controller?.

graememk

If it's in 14 yrs it would have reached that temperature on many occasions.

Are you noticing the hot taps are too hot?

_Brian

https://www.boards.ie/discussion/comment/122122242#Comment_122122242

your right. It’s possible it’s reached that temp before. We have an additional sensor on the tank so only seeing actual temps recently.