My daughter has an all electric house and she said that one of the storage heaters seems to be very hot. I am thinking that the thermostat on the "Input" control may have failed and the contacts have stuck.
Any views on the likelihood of this? Any other points to consider before I drive over to look.
A possibilty, of the 4 storeage heaters we have 2 have had failed thermostat units but with burnt out connections rather than failed contacts. They fail to off rather than on though. Or maybe the mechanical heat output control has jammed open.
If you can't get to it quickly I suggest that you tell your daughter to switch that heater off at the wall. It should have a switch where the cable from it goes into the fixed wiring. Failing that pull the appropiate fuse or trip the apprpiate breaker in the off peak consumer unit. If the input stat has stuck on it'll do nasty things to her power bill and is a reasonable fire risk.
Thanks for that.
I think the model is a Heatstore HSAF18N and the thermostat is part no XL9837.
I will go and investigate next week. I am wondering if the thermostat sensor could have got moved from wherever it should be. I will get my daughter to investigate if it clicks at any point on the dial.
Thought I'd google that model number to find more info. Only one hit, this thread. Fipping heck, that's quick to be indexed by google! Add heatstore and you get a few more hits but for model hsx18...
If it's hot it probably won't click at any point as it won't be wanting heat... and a clicking stat only means the bistable strip is moving not that the contacts are actually opening/closing as they should.
Dave - had a look today (bloody hot!) what it the centre thermostat for? The left is for the fan and the right is input - in between was one that is operated with a preset screw. I tweaked it toward the "open" position
One knob is input charge (E7).
- Knob adjusts a bimetallic thermostat to module charge level during the overnight E7 charge
- eg, knob set to "1" causes charge to cycle on/off at 4am, knob set to "6" causes charge to cycle on/off at 6am
One knob is output charge (room temperature).
- Knob turns a screw which adjusts the preload on a bimetallic lever
- The bimetallic lever pushes against a counterbalanced flap running along the top of the heater core
- Adjusting the preload alters the temperature at which the flap opens the core to convection
There is also a cutout thermostat.
- E7 charge period must be limited by a timer to 7-8hrs
- By which point the core will be 920-980oC
- If the timer sticks on this cutout prevents overheat & fire
E10 can mean heating outside of E7 periods.
- E7 is basically a 7hr overnight charge
- E10 is a 10hr charge, but over 3 discrete periods
- eg, 4hr overnight, 3hr afternoon, 3hr evening
If the heater is very hot:
- Does the time correlate with E7 or E10 timed charge?
- Is the boost element running - 750W?
E7/E10 is handled by a timer.
- E7 - timer by the heater, at the CU or DNO teleswitch
- E10 - timer at the CU or DNO smartswitch
If the timer jams on the heater will run until the thermal cutout operates. If the cutout does not operate and the heater is against a plywood or hardboard wall it can set fire to it, or wallpaper. This is extremely rare, but has been known. The cutout is either push-button reset or one-shot thermal fuse (or both, since some heaters have more than one safety trip like tumble dryers).
Turn all power off if possible and check the meter - a 3.3kW 24kWhr heater will draw 3.3units/hour if on charge. If it is E7 and you are seeing it draw current at 9am then a) the timer is stuffed or b) the contacts have welded themselves on. If instead 0.75units/hour are being drawn, then the boost element is running and the switch is stuffed.
I suspect the 750W element can run continually without triggering the safety cutout - it will just get hot.
There is no flap operated by a lever.
The heater is a Heatstore HSXAF24N.
The boost element is a Fan Heater type of thing in the bottom. The circuit is normally off.
Interesting, so it relies on the fan to output heat or pure convection?
When it was "very hot" was it drawing any current? Just to rule out a fault on the remote timeswitches.
Interesting, so it relies on the fan to output heat or pure convection?
When it was "very hot" was it drawing any current? Just to rule out a fault on the remote timeswitches.
It wasn't drawing current this afternoon.
The fan is the first stage of "Boost" - the next stage is to introduce another coiled element.
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