Storage heater not heating up but powered

jjjinx · Feb 25, 2022

Hi guys,

I'm on a job where one of the storage heaters isn't heating up. it is a dimplex model FXL18N 2.34kW.

There are two of these heaters in the property but one is not heating up. I've checked & bypassed the supply using peak supply to verify that electricity is getting into the heater.
At the elements 240v, resistance is 23.7 ohms.

The control / thermostat clicks when moved but no change in resistance at the element & there is no disconnection of electricity when the thermostat is turned to zero. I've duplicated the test at the other heater & exactly the same results.

No thermal trips as there is electricity at the elements live & neutral, can anyone think of anything else i've missed or can try?

Cheers Jon.

Mark K · Oct 31, 2023

Rockingit said:
You might want to be careful doing that - the last storage heater I had to actually fully replace had gone pop because the old boy had pee'd into it. Yep - you read that right! All the internal insulation blanket was sopping wet with urine. That was not a fun job.

I opened it to look at the thermostat. Cut out not open, zero ohms between red and white wires so should get heat. When first turned on seem to be a bit of heat - checked with laser thermomenter with vent open - a few degrees C above ambient then goes cold. Measured resistance between neutral and thermostat output - Megohms. Can these lement fail in such a way theat they heat up a bit and then go open circuit with just a small rise in temperature? Dimplex DXLN

brianmoooore · Oct 31, 2023

Mark K said:
Can these lement fail in such a way theat they heat up a bit and then go open circuit with just a small rise in temperature? Dimplex DXLN

Not impossible, but unless it's the smallest version in the range, there are more than one element connected in parallel, so they would all have to fail to get an open circuit reading OR the wiring between the 'stat and the first element has failed..

Mark K · Nov 9, 2023

brianmoooore said:
Not impossible, but unless it's the smallest version in the range, there are more than one element connected in parallel, so they would all have to fail to get an open circuit reading OR the wiring between the 'stat and the first element has failed..

Oh Dear - measured the resistance between the neutral of the additional day-time convection heater and live of storage section so no wonder I got open circuit! Before I realised this, I opened up the unit and all elements are ok. Just looked at input section and found the attached - well cooked- no voltage across elements - will replace chock connector and cut off burnt bit of cable. Don't know why was getting small amount of heat on switch on before - perhaps thermostat gone as well.

Mark K · Nov 15, 2023

Mark K said:
Oh Dear - measured the resistance between the neutral of the additional day-time convection heater and live of storage section so no wonder I got open circuit! Before I realised this, I opened up the unit and all elements are ok. Just looked at input section and found the attached - well cooked- no voltage across elements - will replace chock connector and cut off burnt bit of cable. Don't know why was getting small amount of heat on switch on before - perhaps thermostat gone as well.

Has anyone known mains cable to go open circuit just from overheating. The wires were completely black when I took them out. Put in new ceramic block and it seems to be working ok now. So elements and thrmostat have lasted 20 years with no problems.