Credanet Storage Heater installation

Published November 29, 2008 by Sean

Update 8Dec 09 Credanet Controller module for sale, little used, as new (and cheep since I have no use for it now).

Update 16Dec’11 : I still have this controller available for sale, although my recommendation would be to junk the system and go for an ASHP.

I’m stuck in the middle of nowhere with only electric heating, so I thought that an intelligent fan storage heater solution would be a good idea. When I first started using it, it seemed to work well, although I wasn’t sure it was saving much electricity.

I had some problems with it last year, and ended up doing a full system reset. It turns out that when they say ‘don’t switch off’ they really mean it. Powering down the system can result in it needing an installer-level reset, and of course the process is secret.

To reset a CNT18FW heater, first be very careful not to electrocute yourself. Switch off both supplies, and remove the lower pannel. Remove the 2 leads to the PCB from the room temperature sensor, and replace with a short between the two pins. Check nothing else is shorted, and power on. After 5-10 sec, the LED should flash, indicating the heater has been reset.

To reset the controller, dis-connect from the mains, ans set the battery switch off. Re-connect/disconnect again, and switch battery on. It should now be factory reset.

To enter installer mode,

Switch to ‘holiday’

Press 2,6,3,5,5.

Warm reset, press 3+9 together.

Filed under Heating

Comments (11)

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  1. Sean says:

    Just in case you’re here wondering about the merits of the Credanet system, my impression (as a designer of embedded microcontrolers) is that the technology is just not understood by the people designing it. I didn’t notice any significant savings in energy use (being out most of the day), and ended up destroying the controler PCB in my heater. I replaced it with a homebrew version, and felt even more that storage heaters are not really a good option.

    Posted June 24, 2009 @ 10:27 am (UK)
  2. Sean says:

    If you are in the position of having to work with a faulty Credanet system (and you don’t need my spare controller) I’d seriously consider looking at heat pump (GSHP) solutions. I am intending to do a new cost analysis soon (to compare with the 2002 quote of £7000 I had for an oil system)

    Posted December 16, 2009 @ 10:58 am (UK)
  3. Sean says: for comprehensive fault-finding info.

    Posted January 9, 2010 @ 12:41 am (UK)
  4. Mike says:

    I have one of these Credanet systems in our new house – it worked when we moved in, but decorators turned everything off to paint around the sockets and it hasn’t worked since. I have come across the Installation Instructions, and have run through them many times, but this fails to kick things back into like.

    We paid for an installation engineer to come around – he said our module was faulty. He tried his spare module but this didn’t work either. I bought another and this is exactly the same as my original….not working still. His recommendation was to have the heaters converted to standard storage heaters at £200 a pop. We would need to replace the convectors in the bedrooms.

    Anyway, I read with interest that you performed a reset of your heater by shorting out the temperature sender pins. Do you have any information on how to short them out (for example do I whack a screw driver across the pins or what?) and whether this fixed the problem? Many thanks, Mike

    Posted February 11, 2012 @ 10:58 pm (UK)
  5. Sean says:

    Hi Mike,

    It really shouldn’t cost £200 to convert one of these to a standard storage heater – all it would take would be to add a thermostat. However, if you’re up for trying the reset, I think what I did was to use a proper electrician’s insulated screwdriver to short the two pins.It did fix it for me, the first time… Then I killed the control PCB by shorting the wrong thing – and ended up building my own microprocessor based controller. I was never happy with it, and just spent £9000 on a full new air source heat pump and radiator system…

    Posted February 12, 2012 @ 2:03 am (UK)
  6. Andrew says:

    Hi Sean

    All very interesting reading. I have a CredaNet (version I) system and I think a total of 3 main controller (they call it the transceiver) boards have failed over the years.

    I was thinking of my own microcontroller board but going one step further and having inputs for both current and forecast (hourly for the next 24 hour) outside temperature.

    What I haven’t a clue how to do is write the necessary algorithm. Obviously it will have to learn, because I can’t possibly know what the correct equations are. Any thoughts would be greatly appreciated.

    I considered building up a table of values but there are too many dimensions. Basically I want to know how much heat input to provide during each of the three low-rate periods (I’m on Economy 10) to give the desired room temperature, given:

    1. The forecast outside temperature for each of the next 24 hours (Raspberry PI can get this for me from the internet)
    2. Desired temperature setting for each of the following 24 hours
    3. Current actual room temperature
    4. Actual outside temperature
    5. History of what’s happened over the last 72 hours

    Seems far too complicated to me (and probably not likely to be significantly better than a manual control in reality!).

    Plus of course operating the fans as required to run air over the elements.

    Posted September 12, 2012 @ 8:59 pm (UK)
  7. Sean says:

    I used a cheap arm-7 board from embedded artists, sensing the on-board store temp and room temp thermistors. I found these sensors very susceptible to air flow variations and never really managed to find a good compensation algorithm. In the end, I fell back to a static control of overnight heat loading, and manually adjusting the set point for the fan on the fly. You might have a little more success with the R-pi since it will be easier to log temperature plots to disk and analyse. I’d suggest a remote room stat, external temp compensation from a forecast (My 2 bed bungalow takes about 100kWh/week for a 60 degree day week, start by using forecast temp below 16C to modify 50% of your pre-load energy), and current temp to modify room setpoint by a degree or two (on a warmer day, you can cope with slightly cooler room fabric).
    Your algorithm can monitor how late in the day the core reaches ~50C and use this to adjust the parameters (manually, or closed loop).

    Getting the algorithm spot on will not save much by my limited experience. We’re talking probably some fraction of 30kWh per week which you waste from a bad algorithm. First half is easy, last 5% is impossible.

    Proposal for fan control – use the inputs to determine a fan duty cycle to run. Duty ~ (Set-room)*(Weather comp factor)*(1-((Tstore-50)/500)).

    Good luck!

    Posted September 12, 2012 @ 9:25 pm (UK)
  8. Sean says:

    Source for my control project is here:
    (at least the main part. It uses some framework code that came with the board)

    Posted September 12, 2012 @ 10:46 pm (UK)
  9. Andrew says:

    Many thanks, all useful ideas. I’m wondering whether the complexity is all too much (although I don’t mind having a go and tinkering as I go along to see how it pans out), Perhaps the best solution is a self-learning neural network. I see these being used now in things like NEUROBAT although this is intended for hot water radiator systems which don’t suffer quite so much lag!

    Posted September 13, 2012 @ 1:48 pm (UK)
  10. Andy says:

    Hi, thanks for your post very interesting! Do you happen to have any of the operating/installation instructions for this? Every link I have looked at is dead! Would be very greatful if you could help.

    Posted September 20, 2012 @ 4:53 pm (UK)
  11. Sean says:

    I searched all my PDFs on my machine, nothing drops out as seeming likely – unless you have a document name that might be worth trying? Probably too long ago… Have you tried the manufacturer?

    Posted September 20, 2012 @ 11:45 pm (UK)

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