Dimplex XLE150 Storage Heater with a Fan Control Problem. Also Model Variant options. Are there any?

[Reptech]

Where to begin.

An XLE150 of mine has suddenly developed a strange issue with the fan which is continuing to run when a 'Comfort On' period ends. This started 3 days ago and the behaviour seems consistent. Even after 15 minutes the fan still runs although the display correctly shows 'Comfort Off'.

The only way to stop the fan is to disconnect the supply for 3 or 4 minutes. Reapplying power behaves as normal and the fan is OFF. IF I select 'Advance' at this point to 'Comfort On' the fan starts correctly but again will not shut down when manually going to Comfort Off'.

When I have tried the above, the main 'Comfort On' period that has ended has been on for some 4.5 hours in the evening. What is strange is if I try a manual 'Comfort On' in the morning for say 5 minutes the fan runs as expected and now will shut down under control of the 'Advance' button.

I tried a 'Factory Reset' from the control panel (twice) with no success and then also tried removing the coin backup battery for an extended period followed by another reset. Still the same.

I will hopefully have access to another XLE main circuit board to try but the thought crossed my mind that these boards fit the whole model range and so there might be a question of how the board is initially programmed or set up to tell it which version (kWh rating) it is installed for? Or is that info held by the User Control Panel?

Is there a 'hidden' service mode available on the control panel to set this version info?

I can find no service info anywhere related to any of this. Could a Quantum model also be similar? although I still couldn't turn anything up for those either.

So if anyone has any experience or thoughts at all on any aspect of this they would be most welcome.

 

[binky]

Sounds like a dodgy control, but probably worth contacting Dimplex helpline for advice, especially if still under warranty.

 

[Reptech]

It does all sound a bit that way tbh. For curiosity I've just programmed it to come on for 20 minutes at lunchtime to see if a short 'Comfort On' time gives the same fault condition. I'll update with the result of that later all being well.

The heater was installed summer of 2020 so pretty new but out of warranty. I'm kind of 50:50 at this point as to whether its a genuine 'hard fault' meaning a component issue or a weird 'logic lock up' type of condition.

There is some documentation I have that says it can take the fan 'up to' 1 minute to respond and 'this is not a fault' which to me is a curious behaviour to the design anyway. Having said that it usually takes around 4 or 5 seconds for the fan to respond normally.

Even with a reset some info is still retained in the user logs so its not a total reset if that makes sense.

 

[binky]

the 1 minute would be a cooling down period for the heating element.

 

[Reptech]

Good thinking on that, yes that could well be. I hadn't considered that.

So the lunchtime test went off without incident. The fan cut off as it should although it was only a relatively short 'Comfort On' period. I've set it to come on again at 18:05 and to go off at 19:30 rather than 22:40 as it was originally before this trouble started. Lets see what happens with that one.

Around 20:00 I'll manually turn the boost on for 2 hours (setting to fan only, no element) and see if it turns off on that setting.

This might sound a bit 'out there' but these heaters make a slight twittery power supply noise all the time. Its very very faint but they do...
I've noticed when I used the 'Advance' to cycle the comfort periods on and off at the end of the day when the fault appears for real I can hear the sound change slightly. It takes on a slightly buzzy character. Turn comfort on and that buzzy sound disappears but the fan runs the same through it all at what seems to be probably the slowest speed.

So the command to turn off seems to be doing 'something' even though the fan carries on. Most of the switching on these for the elements and so on is done through solid state circuitry using Triacs but there is a single small relay on the board. I read somewhere that was for the boost element which is just the lower one of the three fitted.

I have some pictures of the control board which I can post for interest.

 

[Reptech]

Just for interest.

The main board and room sensing thermistor (the wire and plug)



The Triac switching for the elements and I think also the fan. The MOC3023's are optically isolated triacs to fire the high power ones on the heatsink. The fan connects to the two terminals in the upper right of the above image. The 2kW tabs are for the two parallel elements and the 1kw for the one also used as boost. Must admit the relay is near those terminals... one to investigate I guess.



And the small relay. I still think this handles the boost element. I say that because the fan can run at different speeds and so it needs more than just an on/off option.

One to ponder over the weekend.