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Do I need two mains supplies for boiler and wiring centre?

Former Community Member
Former Community Member

Good evening, Just like to say hello and that I am not a gas engineer or an electrician, but I would just like to understand what I need to ask for. I have a question about an old y-plan central heating installation dating back to 2000. I have an old Gloworm micron 50ff boiler situated in the consumer unit cupboard. However, it is connected to the wiring centre situated in the hot water cupboard 6 meters away via 3 wires, switched live, neutral and earth. I also have an old Grundfoss pump connected into the wiring centre that has only 4 wires, Blue, orange, brown-white, and grey, (I notice new pumps have 5 wires). The pump also has 3 settings using 40,65 & 95 watts. I also have 3 port mid-position valve, room stat, hot water stat and 2 channel programmer, (all from Danfoss heatshare pack).



 



Due to limited access in consumer unit cupboard I am limited to fitting either a Worcester greenstar ri series boiler or a Baxi ecoblue advance. Looking at the wiring diagrams, with my limited understanding, does fitting the Bosch require separate mains supplies in each cupboard, one for the boiler and one for the wiring centre and will the pump kill the boiler using an extra 5 watts as the worcester boiler is rated at 90 watts, and could I still use it with only 4 wires or would I need a new 5 wire pump too.



 



Or would it be better to go for what seems to be the simpler option of the Baxi as it requires no pump overrun or permanent live and looks as though it is fed with just live, neutral and earth from the wiring centre as I have now.



 



Sorry about the long question, and many thanks in advance. Simon.


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  • 0

    Sparkingchip:

    Did I say that we would not work around what is already installed?


    As the the original poster wants to keep the existing three port valve, pump and controls I assumed it would need a system boiler without all of those built into it in the factory.


    ?




    Quick posting whilst really concentrating on other things leads to posts that may not make sense as there is a clear contradiction in that post!


    However I wasn’t particularly trying to recommend any specific boiler, this is the second discussion lately where there has been a proposal to have two electrical supplies to a heating system.


    The topic heading is “Do I need two mains supplies for boiler and wiring centre” and my answer is no and actually it would be extremely dangerous, ideally take the supply into the boiler then connect the wiring centre and everything else so that when the boiler is disconnected everything else goes dead as well.


    There are some central heating systems around with extremely dangerous wiring, don’t assume that what is already there is safe and reusable.


    Andy Betteridge 

Reply
  • 0

    Sparkingchip:

    Did I say that we would not work around what is already installed?


    As the the original poster wants to keep the existing three port valve, pump and controls I assumed it would need a system boiler without all of those built into it in the factory.


    ?




    Quick posting whilst really concentrating on other things leads to posts that may not make sense as there is a clear contradiction in that post!


    However I wasn’t particularly trying to recommend any specific boiler, this is the second discussion lately where there has been a proposal to have two electrical supplies to a heating system.


    The topic heading is “Do I need two mains supplies for boiler and wiring centre” and my answer is no and actually it would be extremely dangerous, ideally take the supply into the boiler then connect the wiring centre and everything else so that when the boiler is disconnected everything else goes dead as well.


    There are some central heating systems around with extremely dangerous wiring, don’t assume that what is already there is safe and reusable.


    Andy Betteridge 

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