Cylinder Immersion Heater Tripping

GarethW · Mar 7, 2022

Hoping someone can give me some advice.
My cyclinder immersion thermostat is tripping every few days.
It hasn't been used for a few years, but now, because I got Solar panels and an Eddi connected, we've started using it again.
I've established that the Eddi, nor the top thermostat, is faulty. Both have been replaced, and the problem persists.
The problem is that the thermostat keeps tripping, and when I press the reset button, it works again. But a few days later, it trips.
Could you bottom element be at fault? Could it somehow be the wiring in the system? Any other potential areas to consider?
Any questions welcome. A pic attached.
Many thanks.

snowhead · Mar 7, 2022

The top safety thermostat is tripping it's because it's detecting over temperature in the cylinder or it's faulty and falsely detecting over temperature.

If there is another immersion heater below it then the temperature setting on that one may be set too high causing the top of the cylinder to overheat and trip the top over temp safety themostat.

Is the water from the cylinder very hot?
And is the bottom thermostat turned up high the same as the top one (in the picture), if so that's the problem (or the bottom stat is faulty)?

GarethW · Mar 7, 2022

snowhead said:
The top safety thermostat is tripping it's because it's detecting over temperature in the cylinder or it's faulty and falsely detecting over temperature.

If there is another immersion heater below it then the temperature setting on that one may be set too high causing the top of the cylinder to overheat and trip the top over temp safety themostat.

Is the water from the cylinder very hot?
And is the bottom thermostat turned up high the same as the top one (in the picture), if so that's the problem (or the bottom stat is faulty)?

Thank you for the reply.

The water in the cylinder is typically very hot, yes. Not boiling by any means, but very hot.

I don't see a temperature adjustment on the bottom thermostat. Should there be one? Pic attached.

Can I just lower the stat in the top? I see there are two temp controls at the top. One with the red switch, and the other has 1-5. Which one (or both) should I lower a little?)

Thanks.

Thanks.

James · Mar 7, 2022

lower it a little and see if the problem persists.

GarethW · Mar 7, 2022

James said:
lower it a little and see if the problem persists.

The red dial? Or the number 1-5?

James · Mar 7, 2022

i would lower both by 1 mark and see if it fixes the problem.

johntheo · Apr 7, 2022

Presuming the

GarethW said:
The red dial? Or the number 1-5?

I presume the Unival is the safety stat?, if so I would leave that at 5 and assuming the adjusting screw above it (set to 4) is the control stat, when the water is very hot but hasn't tripped the safety stat, turn the "4" adjustment screw down until you hear the control stat clicking off, turning the safety adjustment down should test the safety stat setting?.