problem with Dimplex Duo300n heaters

Avo Mk8 said:

It seems you are doing all the right things with the controls.
Yes the idea is to have background turned up enough to give you the heat you need through most of the day, and as you say, you probably don't need much, if any, comfort heating at all. Since the elements are not being switched on by the controllers, in the ones that don't work, for some reason, it really doesn't matter how you leave them set at the moment!

The frustrating thing is that what you really need at this point is a competent engineer with a multimeter (preferably an engineer with experience of such appliances) to check what voltages are where, and it should become quickly apparent what's wrong. You need to befriend an electrical handyman!! But then knowing what's wrong may still not fix the problem - there may be more expense searching for, purchasing and fitting parts (where available)

So why are the background heating elements not coming on?
My thoughts on possible reasons:
The off-peak supply is not getting to the heaters that don't work.
The RXPW4 controller is preventing, or not enabling, background heating because of the status it has set on the pilot wire (of the heaters that are not working)
Something within the controller of each heater has broken (but why 3 heaters all 'faulty'?)
The fusible links for the background heater have blown (but as above)

So one last suggestion - could you focus on the RXPW4 controller, and check if there is anything you are supposed to set it to to enable background heating. Presumably you have instructions for that?

Thank you for your perseverance too!

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Thank you again very much. Yes I have the instruction for this controller - again old type but will do. Will read it, yet the two questions/comments I have remain:

A. somehow 1st heater and the water heater , which both were also connected to the controller still works now. Very likely they both were in a different/separate zone, and only other zones where the other heaters are might have been affected by "something" connected to that controller. At least this is my understanding of this situation.

B. When I turn this control on, will it automatically go to the old set up, or will I have to set it up from the beginning? The previous tenant told me that the zones were automatically set up already.

And one more question in relation to it "...and check if there is anything you are supposed to set it to to enable background heating..." if there will be something I would need to set up, would it mean that I always would have to have this controller on? There are flats here where they do not use it either and the heater are working. Maybe once set up, it has to be somehow properly "un set up/disconnected/disabled" rather than by switching the power on the wall, this is what I did as someone told to just do it this way.... what a mess, but we will get there. Rather scared to turn this controller on as again worrying about this working heater and the hot water heater - hopefully they are not going to be affected.

Once I have some more news in relation to it, I will post it - it might not be tomorrow as I will try to talk to one person who uses that panel and should know more, not sure when this person would be available though. Have a good evening

Agaxyz said:

Thank you again very much. Yes I have the instruction for this controller - again old type but will do. Will read it, yet the two questions/comments I have remain:

A. somehow 1st heater and the water heater , which both were also connected to the controller still works now. Very likely they both were in a different/separate zone, and only other zones where the other heaters are might have been affected by "something" connected to that controller. At least this is my understanding of this situation.

B. When I turn this control on, will it automatically go to the old set up, or will I have to set it up from the beginning? The previous tenant told me that the zones were automatically set up already.

And one more question in relation to it "...and check if there is anything you are supposed to set it to to enable background heating..." if there will be something I would need to set up, would it mean that I always would have to have this controller on? There are flats here where they do not use it either and the heater are working. Maybe once set up, it has to be somehow properly "un set up/disconnected/disabled" rather than by switching the power on the wall, this is what I did as someone told to just do it this way.... what a mess, but we will get there. Rather scared to turn this controller on as again worrying about this working heater and the hot water heater - hopefully they are not going to be affected.

Once I have some more news in relation to it, I will post it - it might not be tomorrow as I will try to talk to one person who uses that panel and should know more, not sure when this person would be available though. Have a good evening

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Thank you for this.

To answer A: if the water heater is connected via the Dimplex "Pilot Wire Interface Unit" (see my ramblings at the end below) to the controller, and the controller is switched off, the water heater will be permanently 'on'.
I'm beginning to understand that if the wall controller is 'off', and hence the pilot wire is 'off', then the heaters should just work from their buttons, but with none of the additional features of the wall control. However that's not completely borne out by the wall controler instructions below.

To answer B: If you turn the controller 'on', it will remember and revert to the original settings used by the previous occupants, according to the instructions.

Re the "one more question", I think I have established that your heaters ought to work with the controller in the 'off' state.
So don't worry about that, just leave the controller 'off' for the time being.
The curious thing is though, that the instructions for the controller do say that the controller should be set to 'comfort' (the sort of sun symbol) for the heaters background mode to work. see the trouble shooting part of the guide here:
So you might summon up your courage and set the wall controller to 'comfort' and see if anything changes overnight. If not, return it to 'off'!

To continue the fault finding game (!), I recommend you do a check of the off-peak fuseboard feeding the radiators:
You probably have two 'fuse boards', one for the normal power to sockets and lights etc, and one for the off-peak heaters. You should be able to tell which is which from the little labels by the fuses (MCB's). I would like you to make sure all the heater switches/'fuses' are "ON" !
If you have difficulty identifying what is what, a photo attached to your next post would help.

On the subject of your working hot water tank, I have been looking at the information on the Dimplex RXPWIF "Pilot Wire Interface Unit" that would be the connection between your wall controller and the tank, here:
This says that if the controller is switched 'off', the water heater will be on all the time. Which will be why you have hot water.
It would be useful to check if you can see a RXPWIF box on the wall wired to the immersion. If not, maybe the immersion heater is just wired directly to the off-peak supply.

Going back to your mention of the three switches on the wall for each heater (Which are presumably for day-rate power, night-rate power, and pilot wire for the controller). Is it the case that all three switches are on for all heaters (apart from the faulty/noisy one)? Has the first heater that's working properly got all 3 switches on?

Finally, can I ask if you are owner or tenant? If the latter, surely the Landlord has responsibility for sorting this out?

Avo Mk8 said:

Thank you for this.

To answer A: if the water heater is connected via the Dimplex "Pilot Wire Interface Unit" (see my ramblings at the end below) to the controller, and the controller is switched off, the water heater will be permanently 'on'.
I'm beginning to understand that if the wall controller is 'off', and hence the pilot wire is 'off', then the heaters should just work from their buttons, but with none of the additional features of the wall control. However that's not completely borne out by the wall controler instructions below.

To answer B: If you turn the controller 'on', it will remember and revert to the original settings used by the previous occupants, according to the instructions.

Re the "one more question", I think I have established that your heaters ought to work with the controller in the 'off' state.
So don't worry about that, just leave the controller 'off' for the time being.
The curious thing is though, that the instructions for the controller do say that the controller should be set to 'comfort' (the sort of sun symbol) for the heaters background mode to work. see the trouble shooting part of the guide here:

https://www.dimplex.co.uk/sites/default/files/assets//RXMBS4_RXPW4_Operating_Instructions_Issue_0.pdf

So you might summon up your courage and set the wall controller to 'comfort' and see if anything changes overnight. If not, return it to 'off'!

To continue the fault finding game (!), I recommend you do a check of the off-peak fuseboard feeding the radiators:
You probably have two 'fuse boards', one for the normal power to sockets and lights etc, and one for the off-peak heaters. You should be able to tell which is which from the little labels by the fuses (MCB's). I would like you to make sure all the heater switches/'fuses' are "ON" !
If you have difficulty identifying what is what, a photo attached to your next post would help.

On the subject of your working hot water tank, I have been looking at the information on the Dimplex RXPWIF "Pilot Wire Interface Unit" that would be the connection between your wall controller and the tank, here:

https://www.dimplex.co.uk/sites/default/files/assets//RXPWIF_Instructions_Issue_004.pdf

This says that if the controller is switched 'off', the water heater will be on all the time. Which will be why you have hot water.
It would be useful to check if you can see a RXPWIF box on the wall wired to the immersion. If not, maybe the immersion heater is just wired directly to the off-peak supply.

Going back to your mention of the three switches on the wall for each heater (Which are presumably for day-rate power, night-rate power, and pilot wire for the controller). Is it the case that all three switches are on for all heaters (apart from the faulty/noisy one)? Has the first heater that's working properly got all 3 switches on?

Finally, can I ask if you are owner or tenant? If the latter, surely the Landlord has responsibility for sorting this out?

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Hello, could not reply earlier, apologies, busy day.

Thank you for all the links/documents.

Will respond from the end: tenant or owner? Well, there is the 3rd option: I'm both as it is shared ownership The landlord/managing agency would not help in terms of the heaters...

Yes, for the heater that works properly, plus for all the heaters that kind of work, all 3 switches are on.

There is RXPWIF box on one side of the wall (inside the cabinet where the water tank is) and on the other side there are those two switches as per the photo. When the night rates comes on, the switch on the left on the photo is red. I've never used the switch for the immersion, as for me enough water is heated throughout the night (though I know the people who used to live here before did use the immersion as well).

The photos of the fuse boards are also here - from my point of they they all look fine.

In re to "...The curious thing is though, that the instructions for the controller do say that the controller should be set to 'comfort' (the sort of sun symbol) for the heaters background mode to work. see the trouble shooting part of the guide here:.." I had a look at it, and not sure I understand properly what would the comfort mode between 8AM & 10AM – 3PM & 9PM mean? Would it meant that option 1: the heat stored overnight is only shared/given away by the heater between 8AM & 10AM – 3PM & 9PM. Or option 2, does it meant the heaters would use the day heating (at the day rate) as well during those periods to allow the use of the night storage? Or maybe there is the 3rd option?

Also about turning this controller on - I would have to set up the day and time myself when I decide to turn this on (silly questions but better to check) probably yes?

That is all from me

Sorry I haven't replied for a while.
Thank you for the pics, which indicate there is nothing untoward with the power arrangements.

I'm afraid, basically, I know nothing about the controller!
If you decided to try it, I would recommend setting the clock to the correct time.
But I'm inclined to believe the background heating should work with the controller switched off - something you might check with neighbours if you haven't already. If that is the case, I would leave the controller 'off'.

So it seems there's no explanation for heaters not working, other than some failure(s) inside.

As far a water heating is concerned, it seems the main heater is directly on the night rate supply, and although there is the RXPWIF switch there, it's not actively timing the water heater. That's not a problem.

So I fear I don't have any other suggestions. It sems each non-working heater needs to be opened up and fault finding carried out.
The problem here is that an engineer's call-out charge, hourly rate, and the likely cost of spares (and finding them), it likely to be considerable. For this reason you may find you will only be able to get quotes for replacing the heaters, as many may consider the 'repair' option is so unpredictable, they won't want to risk losing money!
This is where a DIY repair (by someone competent) is probably the only economically viable option!

Avo Mk8 said:

Sorry I haven't replied for a while.
Thank you for the pics, which indicate there is nothing untoward with the power arrangements.

I'm afraid, basically, I know nothing about the controller!
If you decided to try it, I would recommend setting the clock to the correct time.
But I'm inclined to believe the background heating should work with the controller switched off - something you might check with neighbours if you haven't already. If that is the case, I would leave the controller 'off'.

So it seems there's no explanation for heaters not working, other than some failure(s) inside.

As far a water heating is concerned, it seems the main heater is directly on the night rate supply, and although there is the RXPWIF switch there, it's not actively timing the water heater. That's not a problem.

So I fear I don't have any other suggestions. It sems each non-working heater needs to be opened up and fault finding carried out.
The problem here is that an engineer's call-out charge, hourly rate, and the likely cost of spares (and finding them), it likely to be considerable. For this reason you may find you will only be able to get quotes for replacing the heaters, as many may consider the 'repair' option is so unpredictable, they won't want to risk losing money!
This is where a DIY repair (by someone competent) is probably the only economically viable option!

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Hello and thank you for all your help, advice and input in general - everything has been very helpful. I will try to sort this out somehow Merry Christmas or Happy Holiday season

Avo Mk8 said:

Sorry I haven't replied for a while.
Thank you for the pics, which indicate there is nothing untoward with the power arrangements.

I'm afraid, basically, I know nothing about the controller!
If you decided to try it, I would recommend setting the clock to the correct time.
But I'm inclined to believe the background heating should work with the controller switched off - something you might check with neighbours if you haven't already. If that is the case, I would leave the controller 'off'.

So it seems there's no explanation for heaters not working, other than some failure(s) inside.

As far a water heating is concerned, it seems the main heater is directly on the night rate supply, and although there is the RXPWIF switch there, it's not actively timing the water heater. That's not a problem.

So I fear I don't have any other suggestions. It sems each non-working heater needs to be opened up and fault finding carried out.
The problem here is that an engineer's call-out charge, hourly rate, and the likely cost of spares (and finding them), it likely to be considerable. For this reason you may find you will only be able to get quotes for replacing the heaters, as many may consider the 'repair' option is so unpredictable, they won't want to risk losing money!
This is where a DIY repair (by someone competent) is probably the only economically viable option!

Click to expand...

Hello again, I have contacted the electrician to come and have the look at those heaters, finally he might come and before the visit the sent me the message - part of the message is below:

"...On my visit as well as discussing the work you require I will also need to look at the existing fuse board. Two other things again we need to check is your water and gas (or oil) bonding. With them being metallic pipes rising from the ground these can carry an earth potential, we need to ensure they have the necessary earthing cables and clamps and run back to the Main Earthing Terminal, again this should be at the fuse board. Sometimes it is not always possible to confirm these 100% of the time but will give us a good idea of what's going on. With the need of having to look at these items (Fuse Board, Water & Gas) it would be good if anything stored in the same cupboards as them were removed so we can get the best view possible...."

I understand the fuse board needs to be checked but the water and gas pipes ( I do not have gas anyway)? Ok I'm not an electrician so is it a standard thing? The electrician wants to come have a look, assess first and next will give me a quote. I thought that when he comes he at once would be able to at least check and if necessary replace the fuses but the switches next to each heater, it seems like a small job (if that needs to be done). I also offered to buy some parts still available on ebay - you had suggested but have not beard about it. It would be more efficient if "simple" things which might casue the issue could be fixed at once, wouldn't it? I am just worried by this email that it already sounds like a huge job...

Agaxyz said:

Hello again, I have contacted the electrician to come and have the look at those heaters, finally he might come and before the visit the sent me the message - part of the message is below:

"...On my visit as well as discussing the work you require I will also need to look at the existing fuse board. Two other things again we need to check is your water and gas (or oil) bonding. With them being metallic pipes rising from the ground these can carry an earth potential, we need to ensure they have the necessary earthing cables and clamps and run back to the Main Earthing Terminal, again this should be at the fuse board. Sometimes it is not always possible to confirm these 100% of the time but will give us a good idea of what's going on. With the need of having to look at these items (Fuse Board, Water & Gas) it would be good if anything stored in the same cupboards as them were removed so we can get the best view possible...."

I understand the fuse board needs to be checked but the water and gas pipes ( I do not have gas anyway)? Ok I'm not an electrician so is it a standard thing? The electrician wants to come have a look, assess first and next will give me a quote. I thought that when he comes he at once would be able to at least check and if necessary replace the fuses but the switches next to each heater, it seems like a small job (if that needs to be done). I also offered to buy some parts still available on ebay - you had suggested but have not beard about it. It would be more efficient if "simple" things which might casue the issue could be fixed at once, wouldn't it? I am just worried by this email that it already sounds like a huge job...

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The electrician will need access to the fuseboard, so asking if things can be cleared out of the way is good. However it sounds to me as if the electrician is wanting to look at earth bonding arrangements in your electrical installation, which in my humble opinion is nothing to do with determining why your heaters don't work (and it will not give him "a good idea of what's going on" with regard to the heaters.! It looks suspiciously as if he is looking for further, perhaps more remunerative, work, or an excuse to conduct an Electrical Installation Condition Report (EICR). If yours is a rented property (sorry - can't remember!) the Landord is responsible for having that done, not you.
You might tactufully sugest he is welcome to review water pipe bonding if he must, but only after he has diagnosed, and fixed, your heaters.
I don't think it is a good idea to buy random spare parts in advance of an electrician looking for the fault.
Just be a bit wary and reiterate that you want a diagnosis of why the heaters do not work, not advice, or a report, on the condition of your electrical installation.

You might have to call an electrician for this so they can test the on peak and off peak flow for you.

Hello,

A bit of an “update”.

A couple of months ago an electrician came to look at those heaters which did not store the heat overnight. It was one brave electrician who did not have much experience with those heaters but was willing to help, all other electricians to whom I had talked to, said it was not worth it to look at those heaters anymore as they were discontinued.

Ok, so the electrician took the heaters all apart to check. It seems the CREDA DIMPLEX STORAGE HEATER CHARGE CONTROL MODULEs were not working in them. So he also took apart that one heater that used to work properly, and from that working heater he took that control module out and put it in the other heaters (those which did not store the heat overnight) to check if it would be working there and if it would make a difference – I am not an electrician, so I cannot specifically say what he did, but he did connect some cables to check the day electricity flow, including the night electricity flow E7 and it seemed it was flowing/working (he was able to check this night E7 electricity flow somehow during the day when he was here - apologies I know my description of what he did is rather “not precise/not professional” yet again I do not know much about the electricity). Anyway, once he checked those other heaters with that control module from that heater which worked he decided that that control module would need to be changed in all of them…(=needed to be changed in those ones which did not store the heat overnight to make them store the heat overnight). Ok.

At the end of the visit, once everything was checked, he put all heaters back to how they were, it also means that he put back the control module which was working last winter into the heater that used to work last winter. It was summer, the heaters were turned off, so I could not check if it was working again as it used it, it was too hot outside as well. Now it is getting colder, I turned that heater that used to work on, but the night storage heat stopped working… I could not believe it….So it does not store the heat overnight = it is cold in the morning, so the background mode is not working (it does not store the heat overnight), but the comfort zone is working.

It seems to have the same problem like with the other heaters. But what happened? It used to work before, and the electrician put the correct control module back in? Could you please advise? Would you have any idea how to make at last this one heater work again? As far as I know/read about those heaters the explanations might be:

• already mentioned: the control module also stopped working (but is this possible that something like this could happen just because he took it out and put it back in)?
• perhaps it is bad connection as he was disconnecting and connecting the parts heater?
• perhaps it is the thermostat (it seemed a little brown when he opened the cover, as the heater was used a lot)?
• Is it possible that I should only need to change the fuse which is next to the “off peak” switch on the wall to make that heater that used to work, work again?
• Any other idea why this one heater is not storing the heat overnight either now? Plus, which of the 4 ideas I mentioned is the most probable?

Someone, earlier in this thread mentioned “….The fusible links for the background heater have blown …” I was looking on the internet for those fusible links but can not sure how they look?

I think what I would like is the list of parts I should buy so when I call this electrician he can check and replace at once what needs to be replaced. The winter is coming, and it would be necessary to have 1-2 of those heaters working… In advance thank you for any advice.

I've been looking at availability of parts, and it seems that's considerably worse now than it was a year ago. There have been no spares available from Dimplex for years as you may know. I could not see any of the spares you need on eBay now, and one charge controller I see that had been for sale in the past went for £150!
Some of the electronic components inside your heaters, such as electrolytic capacitors, have probably reached their end of life, and the reliability of the assemblies may be so impaired that repair of your heaters with secondhand parts may not last long. In fact I think your enterprising electrician has demonstrated that concept - that the remaining parts are now so fragile that they may fail!

I think you have to accept the fact that these heaters are beyond economic repair. Sorry.

I think I might give it one more try. Seem a bit bizarre that those heaters are working in the other flats (not ideally and not all of them but still ...) and all of mine do not store the heat overnight ( plus the one which is constantly buzzing when turned on is totally out of order).. However, can someone please recommend some good heaters with the night storage option as well - just in case I really have to get one...

The general design and the PCBs in these are terrible and have a very short life. The components are underrated and the PCBs are mounted in a hot location, making the problem worse. They are often brown from the heat. They can sometimes be repaired but if the board is burned it's game over.

These are rubbish heaters, you are better off replacing them with the newer Quantum heaters, the design is much improved, though care should be taken to set the parameters up correctly to prevent excessive electricity use.

Agaxyz said:

I think I might give it one more try. Seem a bit bizarre that those heaters are working in the other flats (not ideally and not all of them but still ...) and all of mine do not store the heat overnight ( plus the one which is constantly buzzing when turned on is totally out of order)..

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You could always see if these people can repair the modules in your radiators, if you can get the offending items removed safely:
I have no experience of this seller, though they seem to have good feedback, but I'm not recommending this as the complete solution to your heating issues!

Thank you for the suggestion

Just a question, is it safe to take the module out and leave the heater without it for a week or so? - not sure how long the repairs will take.