Storage Heater with room thermostat query

[Little Plumb]

The storage heater is a Dimplex xms724n and the thermal safety cutout keeps operating. The heater heats up so certainly takes some charge before the cutout operates. Looking at the link below it appears the old cutout stats which are like limpet thermostats are replaced with a repair kit featuring a different designed stat.
http://www.storageheater.co.uk/dimpex/xl-xt/xms724n.html

Whilst I was checking the heater after resetting the cutout I put an ohmmeter across L & N, with the supply switched off, and measured the resistance which was about 18ohms. However no matter which way I turned the input charge control knob, the meter still read 18ohms. Also turning this knob there was no audible click as when the charge switches on/off like on the other storage heaters. The only difference with this heater is there is a room stat sticking out of the bottom of the heater which I assume is connected to the input charge controller. My query is how do these two, room stat and input charge control, interact with each other and should I still hear that audible click when the knob is turned? TIA

 

[EFLImpudence]

The storage heater is a Dimplex xms724n and the thermal safety cutout keeps operating. The heater heats up so certainly takes some charge before the cutout operates. Looking at the link below it appears the old cutout stats which are like limpet thermostats are replaced with a repair kit featuring a different designed stat.
http://www.storageheater.co.uk/dimpex/xl-xt/xms724n.html

It should not cut out in normal usage.
If you cover the heater it may or it could be faulty.

Whilst I was checking the heater after resetting the cutout I put an ohmmeter across L & N, with the supply switched off, and measured the resistance which was about 18ohms. However no matter which way I turned the input charge control knob, the meter still read 18ohms.

That is the resistance of the elements and does not alter (apart from when they get hot). They are either on or off.

It is not related to the control which is either on or of by the temperature.

Also turning this knob there was no audible click as when the charge switches on/off like on the other storage heaters.

If they were cold then the control will be 'calling for heat' all the time.

The only difference with this heater is there is a room stat sticking out of the bottom of the heater which I assume is connected to the input charge controller.My query is how do these two, room stat and input charge control, interact with each other

I do not know how this would or could work.
Perhaps someone else will know what it is.

and should I still hear that audible click when the knob is turned? TIA

That depends on the temperature of the heater.

 

[Little Plumb]

Thanks for reply, heater's not been covered so suspect cutout stat may be faulty.

Nearby storage heaters give audible click between positions 3 and 4 on knob, this one no click from positions 1 through to 6

Definately room stat as per diagrams on link below
http://www.the50plus.co.uk/tech_support/storage-heaters.pdf

 

[JohnW2]

The only difference with this heater is there is a room stat sticking out of the bottom of the heater which I assume is connected to the input charge controller.My query is how do these two, room stat and input charge control, interact with each other

I do not know how this would or could work. Perhaps someone else will know what it is.

I would have said the same. However, the link which the OP provided includes:

"...More modern storage heaters have improved input controls including a thermostat, which senses the room temperature and reduces the heat if the room is naturally warm."

... which I have to say is a new one on me. I would have thought that it would be relatively unlikely that the room would be 'naturally warm' during the night when the storage heater was 'storing' it's heat.

Kind Regards, John

 

[EFLImpudence]

Oh thanks. I missed that and agree about the usefulness.

 

[EFLImpudence]

Nearby storage heaters give audible click between positions 3 and 4 on knob, this one no click from positions 1 through to 6

I would think that is because they are still warm.

Definately room stat as per diagrams on link below

It could be that which has switched off the power.

Does it click.

 

[flameport]

The 'room thermostat' at the bottom is the sensing element for a second thermostat which is designed to react to air temperature rather than the temperature of the heater. These are usually sold as 'auto' heaters, in that they will regulate the input charge based on the ambient temperature, and possibly use less electricity.

If the input knob doesn't click on/off when the heater and room is cold, the thermostat is defective and needs to be replaced. The cutout operating also indicates this, as it is there to disconnect the power when the heater gets too hot due to the thermostat failing.

 

[JohnW2]

The 'room thermostat' at the bottom is the sensing element for a second thermostat which is designed to react to air temperature rather than the temperature of the heater. These are usually sold as 'auto' heaters, in that they will regulate the input charge based on the ambient temperature, and possibly use less electricity.

So it seems - although, as I've just written that is a 'new one on me'. I would have thought that, at the times of year one would usually be using such heaters, it's pretty unlikely that the room would get warm enough 'in the middle of the night' (when the heater was 'heating up') to switch that thermostat off - so I suspect that it is of relatively (or worse!) limited usefulness.

Kind Regards, John

 

[Lectrician]

Faulty input stat. I would swap the input stat and fit the field repair kit to replace the old overheat cutout.

 

[Little Plumb]

Thanks for replies. As the last post states looks like cutout and input stats need replacing. Think the heater might need to be striped down to replace input stat as replacement comes with room stat attached, not sure if the room stat is a capillary tube thermostat type similar to http://www.rathgeber-gmbh.de/pages/capillary_e.html

So a simple fix that's been over complicated by providing an extra stat of dubious usefulness.

 

[JohnW2]

So a simple fix that's been over complicated by providing an extra stat of dubious usefulness.

It does rather sound like that.

Kind Regards, John

 

[Lectrician]

Double check the parts. If your current stat doesn't have a capillary, the replacement won't either. They're typically only on combination heaters.

 

[Little Plumb]

Below is the link for parts available for my model of storage heater, Dimplex xms724n, 2nd picture is the charge stat complete with room stat like the one that's currently fitted.
http://www.storageheater.co.uk/dimpex/xl-xt/xms724n.html

I assume it's a capillary stat because it looks very similar to the bottom stat in this link
http://www.rathgeber-gmbh.de/pages/capillary_e.html

Don't know much about cappillary stats, how they work, or how they act on the charge stat. The capillary tube appears to be fed through the main body of the heater, hence the need for a strip down.