Storage heater not heating up but powered

[jjjinx]

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.

 

[littlespark]

Is there actual elements there?

I worked on one where there was only 2 out of 4 elements fitted.

If there’s voltage at the elements… (between L and N) and the elements are reading a resistance, (not dead short, not open circuit) then there is no reason why the elements don’t heat up. They won’t be hot instantaneously….

Some have resettable thermal trips, others are sacrificial, and would need replaced.

Can you photograph the control panel part?

 

[Dartlec]

As @littlespark says, if the element and not shorted then it should get hot - it's just a wire at the end of the day, nothing clever or sophisticated

If you can, bypass all the control part and wire the element directly into a plug - they often have ceramic terminals at the element side of the circuit.

If the elements are within the thermal blocks it may take a while before the heat is noticeable. May be worth removing the outer layer of blocks to check the condition of elements directly, but unless water has got in they don't often fail there in my experience.

I've had several issues with storage heaters not working in a couple of flats (Storad, not dimplex) and in each case it's been the heat overset that has tripped (a disk that pops up) - and in one case had failed completely...

 

[jjjinx]

Is there actual elements there?

I worked on one where there was only 2 out of 4 elements fitted.

If there’s voltage at the elements… (between L and N) and the elements are reading a resistance, (not dead short, not open circuit) then there is no reason why the elements don’t heat up. They won’t be hot instantaneously….

Some have resettable thermal trips, others are sacrificial, and would need replaced.

Can you photograph the control panel part?

yes there is definitely elements there, thanks for your input. I'm quite versed with older storage heaters but this ones got me vexed.

 

[jjjinx]

 

[jjjinx]

 

[brianmoooore]

If the resistance measured at one of the element's terminals is 23.7 ohms, then the wiring between all of them is OK, as are all of the elements. If you measured 240 volts across the terminals, then they will be heating up.
Have you checked that the 240 volts doesn't disappear after a short while?

 

[jjjinx]

If the resistance measured at one of the element's terminals is 23.7 ohms, then the wiring between all of them is OK, as are all of the elements. If you measured 240 volts across the terminals, then they will be heating up.
Have you checked that the 240 volts doesn't disappear after a short while?

no only stayed there about an hour, I usually get some warmth coming through by then but i'm going to back & double check the results & report back. Unless i've missed something its a little strange, checked between L-E & L-N across the furthest element but as I said will double check.

 

[Petej999]

yes there is definitely elements there, thanks for your input. I'm quite versed with older storage heaters but this ones got me vexed.

Thermal link open cicuit??, fuse open circuit, not switched ON

 

[SJD]

At the consumer unit / fuse box, if the heater is switched on, you should see the appropriate resistance (e.g. around 24 Ohm) between L & N for the outgoing circuit (be sure you have the correct circuit, and not seeing some other load). If not, then it is just a matter of working back through the circuit and the heater wiring itself. Faults tend to be an open circuit in the isolator/FCU, an open circuit internal thermal cut-out, faulty thermostat, also if there is any timer/contactor in the circuit not working.

If all appears good but the bricks don't seem to heat up, I've seen where the thermostat is faulty and operates shortly after powering up, so the heater hardly gets any heat charge.

 

[brianmoooore]

, I've seen where the thermostat is faulty and operates shortly after powering up, so the heater hardly gets any heat charge.

That's why I made my last post. I vaguely remember coming across the same at you once when fault finding a storage heater.

 

[westward10]

You need to measure resistance at the supply terminals to verify the appliance circuit.

 

[jjjinx]

You need to measure resistance at the supply terminals to verify the appliance circuit.

done that, then i measured the resistance at the element while turning the control, then I measured the voltage between L-N & L-E across the element

 

[Mark K]

At the consumer unit / fuse box, if the heater is switched on, you should see the appropriate resistance (e.g. around 24 Ohm) between L & N for the outgoing circuit (be sure you have the correct circuit, and not seeing some other load). If not, then it is just a matter of working back through the circuit and the heater wiring itself. Faults tend to be an open circuit in the isolator/FCU, an open circuit internal thermal cut-out, faulty thermostat, also if there is any timer/contactor in the circuit not working.

If all appears good but the bricks don't seem to heat up, I've seen where the thermostat is faulty and operates shortly after powering up, so the heater hardly gets any heat charge.

I think this maybe my fault. I stuck my snout near the vent and could feel a tiny amount of warmth after switching on but then it soon got cold again.- will open it up and check thermostat - thanks for you post.

 

[Rockingit]

I think this maybe my fault. I stuck my snout near the vent and could feel a tiny amount of warmth after switching on but then it soon got cold again.- will open it up and check thermostat - thanks for you post.

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.

 

[littlespark]

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.

You lot are trying to make me ill?

Between this, and badeggs finger injury…

 

[oscar21]

If its not got warm since Feb 2022 then its a safe bet it doesn't work by now.

Moving on though a multimeter with decent AC amps measurement is great in situations like this, put the meter in-line with the supply and if there is a good few amps of current then there must be heat. We had it with an immersion heater once, client was adamant that she didn't have any hot water yet the cylinder cupboard was always warm and the multimeter read 12A until you turned the thermostat off. The immersion heater was obviously doing it job, where that heat went though was a job for the plumber to sort.

 

[Mark K]

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 am an old boy myself - don't recall peeing in it - but then I suppose I wouldn't remember anyway. I see a replacement thermostat is over £80-00 - would it be too dangerous to bypass that -(I can control the onn/off period) - would this be the same as having the thermostat set to full on?

 

[DPG]

If its not got warm since Feb 2022 then its a safe bet it doesn't work by now.

Moving on though a multimeter with decent AC amps measurement is great in situations like this, put the meter in-line with the supply and if there is a good few amps of current then there must be heat. We had it with an immersion heater once, client was adamant that she didn't have any hot water yet the cylinder cupboard was always warm and the multimeter read 12A until you turned the thermostat off. The immersion heater was obviously doing it job, where that heat went though was a job for the plumber to sort.

Just be careful though - a lot of multimeters have a 10A limit.

 

[oscar21]

Just be careful though - a lot of multimeters have a 10A limit.

Yes, mine has a 20A AC limit, most multi meters don't do AC amps at all apart from maybe the mA range. Its a Proster one, had it for years, I cant even read the lables on the dial properly anymore.

 

[DPG]

Yes, mine has a 20A AC limit, most multi meters don't do AC amps at all apart from maybe the mA range. Its a Proster one, had it for years, I cant even read the lables on the dial properly anymore.

My Fluke 85 will do AC and DC up to 10 Amps.

 

[Rockingit]

My Fluke 85 will do AC and DC up to 10 Amps.

Spinal Tap makes one that goes to 11.

 

[oscar21]

This is what I use.

https://www.amazon.co.uk/gp/product/B00EYYJRC0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

 

[brianmoooore]

We had it with an immersion heater once, client was adamant that she didn't have any hot water yet the cylinder cupboard was always warm and the multimeter read 12A until you turned the thermostat off. The immersion heater was obviously doing it job, where that heat went though was a job for the plumber to sort.

Had exactly that one once. Cylinder was on the ground floor, and a pipe from the top of it went down through the concrete floor and up again under the kitchen sink about 2 metres away. Pipe had been put in with no thought of expansion, and it had sheared cleanly just where it emerged under the concrete in the airing cupboard. It was cut almost as clean as it would have been with a pipe cutter.

 

[Mark K]

I am an old boy myself - don't recall peeing in it - but then I suppose I wouldn't remember anyway. I see a replacement thermostat is over £80-00 - would it be too dangerous to bypass that -(I can control the onn/off period) - would this be the same as having the thermostat set to full on?

I am an old boy myself - don't recall peeing in it - but then I suppose I wouldn't remember anyway. I see a replacement thermostat is over £80-00 - would it be too dangerous to bypass that -(I can control the onn/off period) - would this be the same as having the thermostat set to full on?

Come to think of it the thermal cut-out is part of the thermostat (I suppose) so bypassing the thermostat probably isn't such a good idea. In the above when I said I can control the on/off period I should have clarified that I have a 20 A timer in the circuit also, because my Economy 7 no longer has a separate switched switched circuit.

 

[Mark K]

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]

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]

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]

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.