Electric CH and DHW

Discussion in 'Plumbing and Central Heating' started by JohnBoyII, 15 Nov 2020.

  1. JohnBoyII

    JohnBoyII

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    I've got a traditional gas CH and DHW system in a flat. Due to new regs I can't replace the gas boiler with another gas boiler so I'm going to have to go electric. Is it going to be as simple as changing from a gas boiler to an electric boiler and leaving everything else in place. What are my options?
     
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  3. ianmcd

    ianmcd

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    What new regulations ? no regulations stop you fitting another gas boiler ????
     
  4. flameport

    flameport

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    Unlikely, an electric boiler is likely to be significantly less powerful that the gas one, and there are considerations as to what the electricity supply to the flat can actually provide.
    An electric boiler will cost 4x more to run that the gas one.
     
  5. muggles

    muggles

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    As above, no idea what regulations would preclude you from fitting another gas boiler, an electric one would be considerably more expensive to run
     
  6. ericmark

    ericmark

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    Ronan Point was a long time ago, I know that resulted in no gas in many flats, but as said electric CH and DHW does not really need a boiler as such.

    First is the consideration if worth off peak, if so some storage is required, water storage likely best as it self cools slower, but heavy and bulky, so it is where it will fit, and if the premises and stand the weight.

    Heat pumps are cheapest to run, but also expensive to install. So unless going for a heat pump, the likely independent convection heaters in each room is way to go.

    As to DHW if you want a bath really no option but a storage tank, with a 28 kW gas boiler instant heat it took an age to fill a bath, with a 14 kW boiler it would be cooling down before you have filled it, so for a bath you need a storage tank. If no bath then you can get instant hot water showers and sink units, but likely would be better with small storage tanks around 7 litres, had one in my caravan, it was just 1 kW and because it stored the water could fill a bowl quickly.

    But it does not take much calculating to realise 28 kW from a gas boiler is 122 amp, and most houses have no more than 100 amp, many only 60 amp supply, so it is not as simple as just swapping the boiler. Your looking at a 3 phase supply. What regulations have been quoted?
     
  7. JohnBoyII

    JohnBoyII

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    Thanks for all the replies, I'd love to fit another gas boiler but I've been quoted two problems. Firstly the flue goes through a pipe (about 1.5m) in a cupboard before reaching the outside and there's some rule about not having a flue in a void. The flue was put in more than 10 years ago when there wasn't an issue with flues in voids.

    Secondly, a permanent awning was fitted to the building about 5 years ago, and as it's about a metre (or less) above where the flue comes out of the wall the rule says that the flue has got to go beyond the awning into open air. That isn't possible to do because of the design of the awning.

    I don't really want to go electric but I've had British Gas and others visit and they've all said that I won't be able to fit a gas boiler.

    I found some Strom electric system and combi boilers on screwfix, anybody know if they're any good and if there's something better out there.
     
  8. muggles

    muggles

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    Have you got any quotes from local independents who might be prepared to think outside the box more than the likes of BG?

    Thees no reason not to have a flue in a void. The only real change is that insurrection hatches must be strategically placed to allow the joints to be inspected.

    You could possibly discharge the flue under the awning, if it's effectively just a car port for example. What's the awning used for?

    You won't be able to have a decent electric combi boiler unless you have a three-phase electric supply. You'll need a system boiler and a hot water cylinder if you go down that route. Avoid Strom - they don't make anything, they just rebadge other people's kit and provide little to no backup if there's a problem. Heatrae Sadia are the main manufacturer to look at
     
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  9. JohnBoyII

    JohnBoyII

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    I came across two fitters who were working in the area and asked them to have a look and both said they wouldn't be able to do the job. No harm in asking around and getting a proper quote, or not.

    The awning is probably the bigger problem. The flat is open at the front and there's a balcony, the awning goes from the building to beyond the balcony, so its fairly wide (more than a metre).

    What's a three phase electric supply?, I've got "normal" electrics with a junction box by door. I just thought it'd just wire up to that. Does that mean I'd need to have some electrical work done beforehand?
     
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  11. endecotp

    endecotp

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    Do the other flats in the block face the same problem?
    Was this considered when the awning was added?

    Your realistic electric options are a hot water cylinder with an economy-7 immersion, and either night storage heaters or an air source heat pump. An air source heat pump requires an external unit on the wall or balcony, like an air conditioning system, which makes a noise.

    If you post some photos, I bet one of the experts here will think of a way to install a proper gas flue!
     
  12. vulcancontinental

    vulcancontinental

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    Pictures please. With flues from 60mm dia to 125mm dia and up to 50m in length it's unlikely there's no solution.
     
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  13. muggles

    muggles

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    3 phase is 415 volts - it would be very unusual to have that in a flat, and it sounds like you probably haven't. Without it you're limited to a combi boiler of around 12kW - barely more than a single electric shower can produce for hot water. You could have a storage combi - about the size of a large fridge-freezer. Expensive though https://www.plumbnation.co.uk/site/ehc-comet-electric-combination-storage-boilers/
     
  14. vulcancontinental

    vulcancontinental

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    3-4p/kw natural gas, 14-15p/kw electricity
     
  15. ianmcd

    ianmcd

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    As already asked post some photos , unlikely you cant get a gas boiler fitted
     
  16. JohnBoyII

    JohnBoyII

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    Hope you can see the photos now. The awning was put up about 5 years ago when the LA did some refurbishments.
    There's about 30 flats in the block and as far as I know everyone's got the same flue. The LA changed the boiler in their flats before the awning went up and its
    all looked after inhouse.
    I'd rather stay with gas if I can so any suggestions would be great!



    IMG_1321.JPG IMG_1320.JPG
     
  17. vulcancontinental

    vulcancontinental

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    That's a toughee. Lower the boiler or get a shorter one or a rear outlet model then use an extended flue or plume kit to the edge of the canopy if you can get 6'6" to the underside. Close.
     
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