Creda Sunhouse 79362S storage heater overheating

[youngplug]

Hi everyone, I'm a recently qualified electrician and I've been asked to look at a storage heater that's overheating. Getting too hot to touch apparently. I don't have any experience with storage heaters. Where do I start?
I figure it should have a top limit thermostat. But this document
https://usermanual.wiki/Document/UKSparesBrochure9.1708292019/view
doesn't give a part code for one on this model of storage heater.
And besides, I don't want to go buying and replacing a part if I don't know that that's where the problem is. I've taken a pic inside, nothing seemed visibly and obviously wrong.
I'm looking for direction on how to diagnose and where to go for relevant parts.
Thank you!

 

[flameport]

Getting too hot to touch apparently.

Have you actually confirmed the temperature of the thing?
Older storage heaters do get very hot by design, and someone's perception of 'too hot' may not be accurate.

Correct operation is for the output control (left knob) to be set to minimum, and the input control (right knob) set to an appropriate level based on what heat is required for the next day.
It then heats up overnight. If an extra boost of heat is required in the day, the left output control can be adjusted to release more heat. However that must always be set to minimum at the end of the day.

If the input control (right knob) is turned down to minimum, and then it's left to heat up overnight, it should be cooler than when that's set to maximum.
If it's just as hot and remains hot for the same amount of time, then the thermostat assembly requires replacement (which is what's shown in the picture).

The only other components are the heating elements and a big stack of bricks.

 

[brig001]

flameport is correct, and you should be able to turn the thermostat up and down and hear it clicking. Should be able to test the resistance between the (isolated) live and neutral terminals and see if the thermostat is actually breaking the circuit too. You may need to go later in the day if it has been on high overnight
PS. Ours is too hot to touch today too with 4 degrees outside overnight

Brian

 

[youngplug]

Thanks for your replies.
I'll confess that I haven't checked the temp myself, it's only on overnight obviously and with it being in the bedroom they're not using it now.
They're not new to storage heaters and were saying it was unusually hot, but I'll confirm this with them now.

 

[youngplug]

Hi FP and B1, a bit of an update for you:
I've been back to the property today, they say it was on again overnight and was again too hot to touch, more so than downstairs, so they switched it off in the night. It was still hot when I was there at the end of the day, although in my opinion was not quite as hot as the one downstairs (on similar settings), which was to be expected given that the downstairs was on all night.
The input thermostat cuts in and out fine, you can hear it doing so and multimeter confirms it, reading 0.1 Ohms.
There's no way of turning the limit stat up and down is there, but again multimeter reading was 0.1 Ohms.
The thermal cut out didn't appear to do anything when I tried to reset it. Assuming that I did the right thing which I'm pretty confident about - little sprig of metal sticking up just in front of the limit stat.
So given that the thermostats don't appear broken, I'm erring on the side of changing the limit stat and cut out assembly.
It was too warm to check the elements or that bricks weren't broken.
I did however notice that there was no insulation pad between the front sheet and the bricks. Obviously this is going to cause it to lose heat and feel stonking hot to the touch. And I'd be suggesting this is the only problem, except that the client says that the overheating is a new development.
I'd appreciate your thoughts again chaps.
thanks!

 

[flameport]

no insulation pad between the front sheet and the bricks.

That is the problem.
Replacing the thermostat will achieve nothing.

the client says that the overheating is a new development.

Either they have only just noticed the excessive temperature, or someone's been in there to 'fix' it before you did.