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Discuss Electric Boiler Installation: - in the Central Heating Forum area at

  1. DjClubber

    DjClubber GSR

    Going to be doing a job installing a Full Heating System using an Electric Boiler: -

    Is working out the kw to the property the same way as sizing a Gas or Oil Boiler?

    I am hoping to go down a Combi route in a 4 Bathroom House, 2 Main Bathrooms and 2 En Suites. Not actually seen the Job until Monday. . . But want to get advice on Electric Boilers.

    May have to go down the route of Un-Vented and Electric Boiler setup but prefer Combi. Think its a 4bed or 3bed House in Rural Area and no room for Oil Tank. South East Area. . .

    Not much experience with Electric Boilers, therefore advice gratefully received. And some for instances as had a little look but will proper look after the viewing on Monday. . .
  2. oz-plumber

    oz-plumber Plumber

    Combi - 4 bathroom house?????

    Wrong option!!!!
    • Agree Agree x 3
  3. DjClubber

    DjClubber GSR

    Ok, nothing suitable in Electric???
  4. snowhead

    snowhead Plumber

    Is this a new build or update?
    Has (is) the Electrical supply already been installed?
    Is it single phase or 3 phase?
    Who's doing the wiring for the boiler?

    The first, or a very early thing you need to establish is the maximum load available on the Electrical supply.
    It may not be big enough for an electric boiler especially if it's an overhead supply.
  5. DjClubber

    DjClubber GSR

    Ok, there Electrics are being done by an Electrician. Its a renovation, complete rebuild refurb. . . All I am going to be doing is the Plumbing, Heating, Drainage, all the way through, all Electrics are the responsibility of the Electrician although will brief him with more info. . .
  6. chris watkins

    chris watkins Plumber

    Do you think they have any idea of the running costs of such a system at 13p per kW/h ?

    (Combi) instantaneous hot water is not an option as it requires more energy than the electrical cables can practically supply.

    In answer to your question yes the loading is the same for both fuels, so you will need to do a proper heatloss of the whole house (use the whole house method) to find the required kW's.
    The largest single boiler unit such as the Amptec is 10kW @220 Volts - 12kW @240 Volts, and thats what you need to remember unlike gas / oil the energy available changes as the voltage goes up & down in the system I seem to remember they are allow +10% / -6% from the stated 230 Volts.
    Each boiler unit will require 10mm2 twin & earth from a 50amp supply (bear in mind most house supplies are only 100amp).

    If you do go down the electric route with an un-vent cylinder please don't install an indirect cylinder use a direct & leave the boiler to just do the heating.
  7. DjClubber

    DjClubber GSR

    Ok, so boiler just do the Heating, get a direct Cylinder. ..
  8. chris watkins

    chris watkins Plumber

    It is far more efficient that way & you can reduce to kW loading by heating the domestic hot water overnight (possible using off-peak)
  9. Toby emery

    Toby emery New Member

    What about a High temp air source heat pump ? Expensive initially but at least it’ll do the heating and cylinder. Electric bills would be a fortune.
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