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.

 

[Reptech]

The 6.05pm to 7:30pm Comfort test run passed without hitch. That is odd, the fan shut down after about 3 seconds which is normal behaviour based on past experience. Weird isn't it.. Tuesday, Wednesday and Thursday have seen it carry on running at the late evening shut off point.

I really can't pin this down based on the symptoms as to whether it is a software glitch/stuck corrupt logic etc or a real issue.

It might be worth me trying a disconnect of the user interface panel and its battery backup supply (even though I did remove the battery) from the main board for while.

 

[binky]

so is the fan running on when the night storage heater has been/is working? Sounds like a dodgy thermostat, which should be easy enough to change, perhaps it is breaking down when it gets too hot.

 

[Reptech]

Yes, it runs on when the Comfort On period ends late in the evening.

(last night the 1.5 hour test which went OK. I then set the boost to run for 2 hours and that also worked correctly and the fan promptly shut off at the exact time it should. Next test was to set it back to the full comfort run time which I did last night so it should have taken in the correct energy needed)

Its quite a complex system.

The unit looks at the room temperature that has been set by the user (say 21C) at a midnight when the E7 kicks in.

Based on that setting it then looks at the actual room temperature at midnight and the current core temperature at midnight and also the time it will have to run through the day (the total number of Comfort On periods) to maintain the room at that temperature during those periods.

When Comfort On time comes around if the room is below the set point (21C) the fan will run. The fan seems to be continuously variable in its speed from virtually nothing to a more intense flow to bring a room up quickly to temperature.

It has a separate option to to use 'Fan Only' or 'Fan + Boost' which can switch one of three 1.1kW elements on from the peak supply to increase heat output or maintain heat if the core is low.

Comfort Off is the mode that should kill all processes and the heater should go silent. It doesn't matter then if the room cools, the heater fan stays off.

Manual boost mode overrides that and can be set to run for 1, 2, 3 etc hours. That turns the fan on for that length of time. Again an option to use the element if wanted by the user is available.

Another useful but slightly hidden option is to add in hourly increments of additional charge to the automatically calculated values. I have that set at 1 hour. It gives a slightly hotter heater and less intense fan use needed.

You might find the attached interesting as it shows the info screens and what is monitored.

 

[Reptech]

I've managed to turn this video up on YouTube and although it relates to the Quantum range I'm hoping the XLE range is similar if I should have to swap panels. The hidden service menu... and it has the option to enter the heater size which hopefully answers my question on whether or how the replacement board would know what kWh rating the heater was. That info may in any case be stored in the control panel rather than the board.

 

[binky]

life used to be far simpler

 

[Reptech]

Didn't it just. You're not wrong there.

We're all electric and have four storage heaters and this is the only new LOT 20 type I have.

The one that it replaced was an XL24N from memory. That used to get through a few stats but never any elements surprisingly . You could resurrect the stat's up to a point but a new one was needed every few years. The oldest I have is a Dimplex but the one with a single wire element you thread through the bricks. In many ways that has been the best of all. The stat on that is rugged but has seen the swipe of fine carborundum paper through the contacts over the years. Those and the elements seem unobtanium now. The other two are a Dimplex XL18N and an 'Alto' which is a Dimplex XL24N in disguise. Those last two have the different type of stat fitted with a capillary tube.

 

[Geoff1946]

life used to be far simpler

Cars have gone the same way. Loads of unnecessary, (arguably useless) gadgets and more software than a space capsule!

 

[Reptech]

Wanting to get all my ducks in a row before diving in further I've been trying and trying to locate (any) service info but to no avail...

(and I'll post all this because in months and years to come it might help others)

As regards specific info on how to set/program the heater size (the kWh rating) if the main PCB is replaced I have turned absolutely nothing up. I tried the different button presses and actually discovered a couple of really hidden options, one a % increase setting in charge time and another with three (I think it was three) user/engineer enterable on/off charging periods. That was a scary one...

Time to attack this from a different angle.

I started looking up 'User Interface Panels' because on the Quantum range it seems like you can program these to suit all models in the range but when it comes to the XLE series it seems each User Interface Panel is actually unique and with its own different part number. That could be the answer and explain a lot.

So it seems I might be searching for a programming option that probably does not even exist. The info is Interface Panel specific and permanently written into the small interface panel. Of course that begs the question... which board might be faulty?

 

[Reptech]

An update and further thoughts...

I fitted a replacement main charge controller PCB on Monday and have to say the fan has operated correctly shutting off instantly at the allotted time... and yet I'm still a bit unconvinced strangely.

This is what's bugging me now. The curious note in some documentation stating 'the fan may take up to 1 minute to respond'. I had a chance when fitting the new board to do some quick observations and I can confirm that at the exact second the fan is due to come on that 240 volts appears across the motor winding. Its a squirrel cage shaded pole motor of just 8 watt rating.

So 240 volt across the motor and... zilch. No movement whatsoever. After say 10 to 15 seconds it starts crawling round, crawling as in inching its way forward but very smoothly. It then starts to slowly increase over a minute or so to what is still a pretty slow speed but enough to waft air out.

Is the fan sticky? I don't really know.

The speed as far as I recall is supposed to alter on demand and in past years I've heard it ramp up for a short time and then throttle back. Nothing like that these last few days, even with the old PCB fitted.

So I'm wondering whether we have a motor issue as well... which leads me back to the original issue. Was that real or a symptom of something else? Well it certainly wasn't behaving as it should for a whole week following the sudden 'failure' and with a new board it does behave, at least for the two days running so far.

So second bugging nagging thought... and this gets a bit 'electronici' now. Was the motor not switching off because of some change in back emf on the coil by it running slow (if indeed it is running slow... I'm not certain yet). That can cause triac based switching to 'not let go' and I was certainly aware of a change in sound from the motor as I toggled between fan on and fan off (where it kept running). Was the board trying to turn it off and failing.

Different board, different components, maybe a triac more immune to this effect (high dV/dT rate of change). Who knows. The new board seems to have effected a cure for that.

The fan I might investigate although not immediately. I tried seeing how free it was by pushing the rotor around and must admit it didn't feel all that free but I've zero experience on that. Gently pushing the outer edge of the blades and it all felt more normal.