1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Dimplex Quantum QM150 Storage Heater Off-Peak Electric Supply Wiring Help

Discussion in 'Electrics UK' started by bigp26, 20 Feb 2016.

  1. bigp26

    bigp26

    Joined:
    19 Nov 2014
    Messages:
    17
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Hi All,

    I hope you are all enjoying your weekends!



    Before I start, I just want to thank you for your help in advance…

    To summarise, I had storage heaters installed a few weeks ago by an installer, and have experienced a few problems!

    To cut a long story short, the flat I moved into used to have horrible storage heaters in the living room and hallway, which I replaced with electric panel heaters. I was told that my bills would go sky high (which they did), however at the time, I was a bit stuck as my refurb budget had run out.



    Fast forwarding to a few weeks ago, I had 3 Dimplex Quantum heaters installed. Now the Quantums in the living room and hallway seem to be fine (as the off-peak supply was already there, ready to be connected up via a fused spur), however the bedroom Quantum has given me some issues.

    As there was no storage heater in my bedroom before, there was no off-peak supply. As such, the electrician made the suggestion of simply plugging the off-peak element end of the heater via a normal 3 pin plug into a normal socket, via an electronic timer (to emulate the switching at off peak times to take advantage of Economy 10).

    I asked him if this was safe, and he said yes it was safe, and that it is a much better solution than having to pull a new cable from the other side of the property (literally the other side!). This gave me comfort as I know this electrician also performs electricity safety tests for properties. The DImplex Quantum QM150 was therefore installed in my bedroom using this setup.



    Now for the issues:

    1) About 2 weeks ago, I found that the heater wasn’t charging up with off-peak electricity, and thus wasn’t giving out any heat at any time.

    Having investigated this, I found that the switch for the socket that the 3 pin plug was plugged into, was stuck. I was thus unable to switch it from on and off.

    To test this, I plugged in my iPhone charger and confirmed that no electricity was being output even with the switch in the on position. I put this down to a cheap switch that had gone faulty, and simply replaced it.​


    2) Last night, I could hear some buzzing/crackling from the off-peak socket whilst I was in bed. I therefore went closer to investigate, and smelt a little bit of electrical burning (similar to when using a soldering iron). As such, I quickly turned the switch off and took the plug out of the socket.​

    What I found was that the front of the timer socket (i.e. where the 3 pin plug goes into), was very slightly melted. I also found that the plug was slightly melted on the neutral side. Opening the plug up, I could see that there was damage on the neutral connection of the pin (i.e. to the plastic and screw etc.). Obviously the front of the plug was warm to touch at this point too.​



    This has made me extremely worried, and I have been doing a few hours of research this morning.

    I understand that the off-peak elements of storage heaters are not really suited to be simply plugged into normal sockets (apologies if my terminology is incorrect, but I understand that the normal sockets are connected to the 30A ring main, and similarly, off-peak elements shouldn’t be connected to 30A ring mains).

    I have also read that the storage heaters should be connected with 2.5mm wire (both from the heater to the socket, and from the socket to the fuse box).



    So I’m just weighing up my options before I go back to the install company and start making a fuss:


    Option 1:

    I noticed that the connection between the plug and the timer socket wasn’t great i.e. the pins didn’t sit completely flush into the socket, but sat with a 1-2mm gap. Assuming that this was the issue (i.e. poor connection), the first option is to replace the plug and replace the timer with different models, which are a bit more compatible with each other and therefore don’t exhibit the 1-2mm gap.


    Option 2:

    Get rid of the socket and the plug, and replace this all with a Greenbrook T205-C Fused Timer Spur.


    Option 3:

    Ask the installer to come back and put in a new 2.5mm wire from the off-peak supply fuse box to my bedroom.


    Out of the 3 options, my least preferable option is number 3, as the fuse box and the bedroom are literally on opposite sides of the property, which will mean lots of ugly trunking.

    Option 2 therefore makes the most sense to me, but obviously this means that the off-peak element is still using the 30A ring main. The wire going from the heater to the socket looks like 2.5mm to me, but I think the wire going from the fuse box to the socket looks like 1.5mm (I’m not 100% sure about these wire sizes though – any easy way to confirm?). Considering these points, should this setup be OK?



    Thoughts and suggestions would be much appreciated.

    Kindest regards!
    P.
     
  2. Sponsored Links
  3. Echo the husky

    Echo the husky

    Joined:
    25 Mar 2011
    Messages:
    2,476
    Thanks Received:
    326
    Location:
    Devon
    Country:
    United Kingdom
    The manufacturers instructions must always be followed when installing any electrical equipment, they have not been in this case, and your installer is a fool.

    Option 3 is the only way to go, but call someone competent and registered to carry out electrical work, your installer isn't in this category. Depending on the construction of your flat it may be possible to conceal the cable.

    As the QM150 consumes more than 13A on the off peak part it should never have been connected to the socket circuit. Connecting it via a fused timer spur will just cause the timer spur to overheat and be damaged.
     
  4. bigp26

    bigp26

    Joined:
    19 Nov 2014
    Messages:
    17
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Many thanks for your reply Echo - confirms my doubts so will get onto writing a fairly stroppy email to the installers today.

    In terms of concealing the wire, I have plasterboard walls but have recently had the whole place done up so don't want to ruin all of that. As such, it may be a wall mount and trunking job (but keen to get any other ideas you have!).

    Just a couple of follow up points if you wouldn't mind:

    - Although on the face of it, it looks like the QM150 draws 3300W (http://www.dimplex.co.uk/products/d...g/quantum/quantum/technical_specification.htm), the actual manual says it draws 3024W @ 230V (http://www.dimplex.co.uk/assets/kb/operating_instructions/0/Quantum_Series_F_Installation_Instructions_Issue_1 .pdf). As such, this is slightly above the 13A limit that the plug and timer have. What about if I was to install say a 16A timer?

    - Linked to the point above somewhat, does wire diameter matter a lot? i.e. why are storage heater elements recommended to be connected using 2.5mm, but all normal switches and sockets use 1.5mm?

    Sorry if I sound dumb, but want to make sure I understand this in case another cowboy tries anything funny!

    Cheers
     
  5. OwainDIYer

    OwainDIYer

    Joined:
    5 May 2010
    Messages:
    4,534
    Thanks Received:
    694
    Location:
    Stirlingshire
    Country:
    United Kingdom
    You should NOT connect a load greater than 13A to a general ring or radial socket circuit.

    Usual socket circuits are connected with 2.5mm cable, not 1.5mm. Storage heaters take a heavy current continuously for several hours. They must be connected to dedicated circuits and should NOT be connected b a 13 amp fuse which is likely to overheat even if the heater itself is only 3kW or less.
     
  6. stillp

    stillp

    Joined:
    21 Sep 2009
    Messages:
    4,496
    Thanks Received:
    338
    Location:
    West Midlands
    Country:
    United Kingdom
    You need a better installer. The one you used should not be allowed to trade.
     
    • Like Like x 1
  7. Echo the husky

    Echo the husky

    Joined:
    25 Mar 2011
    Messages:
    2,476
    Thanks Received:
    326
    Location:
    Devon
    Country:
    United Kingdom
    An experienced electrician will have to tools and skills to do a professional and neat job, even if the cable can not be concealed they will likely be able to install it the most discrete way practical.

    Over 13A is still over 13A, You can buy kettles with a slightly over 3KW rating, this is not a problem as they are only on for a minute or two. Your heater will be at full power for some hours.

    A 16A timer will still require a 13A fuse for connection to the socket circuit. It is the fuse running at its rating that is the problem, as the fuse heats up near its rating. Several hours of heating every day causes damage to the fuse holder and eventually causing damage to the point it can't be used any more. The heat will be conducted through the metal contacts of the fuse holder and can cause thermal damage to the switch and the wires connected to the switch fuse.

    'Normal' sockets are wired with 2.5mm² cable. 2.5mm² flex is chosen as the cable will be protected by a 15A/20A fuse or 16A/20A circuit breaker, not a 13A fuse as found in plugs etc. 1.5mm² flex is ok for the smaller heaters and is rated at a maximum 16A. The smaller size will get warm near its maximum rating and can cause heating at terminals on a load that is connected for extended periods, such as storage heaters. 2.5mm² removes this issue. We fit 2.5mm² flex for all heaters except the little 1 element heaters where 1.5mm² flex is used - all heat resisting of course.
    Smaller flexes can be used for appliances plugged into a 30/32A socket circuit because the flex is protected from overloading by the (correctly selected for the size of conductor) fuse in the plug.

    There's no such thing as a silly question. Although there is no specific regulation that says fixed equipment with a heavy continuous load (13A maximum) cannot be connected, it is considered poor practice, and any fixed equipment over 2KW is recommended to have it's own dedicated radial circuit.

    433.1.204 ii Recommends: Not supplying immersion heaters, comprehensive electric space heating or loads of a similar profile from the ring final.

    Your heater still exceeds 13A though so all of this is irrelevant and a dedicated radial circuit is still required. I know this isn't what you want to hear, but your installer should have made you aware it isn't possible to install this heater without installing a new circuit for it.
     
    Last edited: 20 Feb 2016
    • Thanks Thanks x 1
  8. sparkwright

    sparkwright

    Joined:
    20 Aug 2009
    Messages:
    8,253
    Thanks Received:
    1,025
    Location:
    Dorset
    Country:
    United Kingdom
    It's a little strange you have storage heater wiring in some rooms, but not the bedroom - so check first there's no redundant point somewhere in the bedroom.

    Is this a house or flat?

    If it's a flat, sometimes they are wired in conduit, and you may be VERY lucky to draw a new cable in somehow (like I was) - but this is all quite unlikely.

    Running a cable in fitted wardrobes, cupboards, under kitchen units is also a good way to minimise the sight of cable trunking.

    Please feel free to send photos of the property, we may be able to make some suggestions.
     
  9. Echo the husky

    Echo the husky

    Joined:
    25 Mar 2011
    Messages:
    2,476
    Thanks Received:
    326
    Location:
    Devon
    Country:
    United Kingdom
     
    • Thanks Thanks x 1
  10. Sponsored Links
  11. sparkwright

    sparkwright

    Joined:
    20 Aug 2009
    Messages:
    8,253
    Thanks Received:
    1,025
    Location:
    Dorset
    Country:
    United Kingdom
    Thought it WAS a flat...
     
    • Like Like x 1
  12. OwainDIYer

    OwainDIYer

    Joined:
    5 May 2010
    Messages:
    4,534
    Thanks Received:
    694
    Location:
    Stirlingshire
    Country:
    United Kingdom
    Storage heaters were/are not usually fitted in bedrooms, as it was assumed that a small panel heater on overnight would be all that was required, and that would be running off-peak most of the time.
     
  13. bigp26

    bigp26

    Joined:
    19 Nov 2014
    Messages:
    17
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Many thanks for your advice so far. Very much appreciated.

    I've been exchanging emails with the installer all day, so I thought I would provide an update.

    They have been very apologetic, and the last email I received said the following:


    "Can you tell me what series your heater is please? (Under the flap on top it should say Series G or F or E, etc. If it is a G it can be programmed without the use of a timer.

    If it is not a G then it will need a suitable timer capable of switching 3.3KW wired in correctly to a 20amp double pole isolator.

    The heater will also need the 24hr supply for the timer/programming side which you already have with the socket outlet.

    This arrangement has been okayed by Lawrence at Dimplex providing that the off peak supply isn’t on a plug top and correctly isolated (20amp double pole isolator)."

    Any thoughts from you experts?
     
  14. Echo the husky

    Echo the husky

    Joined:
    25 Mar 2011
    Messages:
    2,476
    Thanks Received:
    326
    Location:
    Devon
    Country:
    United Kingdom
    You won't need a timer as the new 3.3KW off peak circuit will need to be wired back to the consumer unit - the off peak one, which will be already be time controlled. I'm probably totally wrong and misreading what they mean, but I read that as they would replace the 13A fused spur with a 20A switch connected to the socket circuit, and then control it with a heavy duty timer. Hopefully I'm wrong, and correctly wired means a new designated circuit wired back to the off peak consumer unit!

    The off peak supply will need to be able to be isolated with a 20A double pole switch (rather than a 13A fused spur), positioned beside the heater, just like your existing storage heaters. The 24Hour boost heater/control supply can be connected to the existing socket circuit with a 13A fused connection unit, the boost heater is less than 1.5KW.
     
  15. bigp26

    bigp26

    Joined:
    19 Nov 2014
    Messages:
    17
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Thanks again Echo!

    One final point - I think the other 2 storage heaters are connected via a 13A fused spur (to the off peak circuit of course). I assume that you would recommend that these are changed to 20A DP switches?
     
  16. The Q150 has a 1500W night storage heater, and a 1300W boost for daytime use,and whilst you shouldn't need to run them together, you always need to protect the user. But that makes a total of 2800w, or 2.8kW, so is actually fine for a 13amp plug - not that I'd advocate that.

    Most storage heaters have a dedicated consumer unit for the night storage circuit, but have the 1300w daytime boost wired into a 20a switched spur coming off the ring main circuit.

    Whilst I couldn't recommend what the installer did, it was creative, and as 1500w is only 6/7amps, it was well within tolerance. I suspect that the first timer was faulty, and the replacement, just a cheap replacement that couldn't handle the current going through it.

    As the installer badly screwed up, I suspect you may be able to get the job done properly (option 3) at a much reduced cost.
     
  17. bigp26

    bigp26

    Joined:
    19 Nov 2014
    Messages:
    17
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Thanks Doggit - I think the night element is actually between 3000W and 3300W (unless I'm mistaken?).

    Do I also need to change the switches at the on-peak end (which runs the boost and internal heater timer etc.) to 20A DP too?
     
Loading...

Share This Page