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Electric boiler - G3 required?

Discussion in 'Plumbing and Central Heating' started by electronicsuk, 29 Jan 2014.

  1. electronicsuk

    electronicsuk

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    With regard to electric system boilers, can anyone tell me whether or not a G3 cert is required to install such a system? As far as I can tell, it carries a similar inherent risk to an unvented cylinder.

    Oh, and before anyone mentions it, yes, I realise electric boilers are the devil's spawn, but due to budget restrictions and lack of gas, it's about the only option.
     
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  3. Agile

    Agile

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    The G3 Cert requirement only applies to vessels of over 15 litres.

    Most pure electric flow boilers would be less than that!

    Tony
     
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  4. electronicsuk

    electronicsuk

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    Thanks Tony, being an electrician I was unsure as to whether it was the system volume as a whole, or the storage capacity inside the boiler itself. Presumably similar rules apply regarding PRV pipework?
     
  5. Agile

    Agile

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    I would expect the PRV pipework details to be included in the maker's installation instructions.

    Tony
     
  6. Dan Robinson

    Dan Robinson

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    Not anymore T.
     
  7. electronicsuk

    electronicsuk

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    Care to elaborate on that, Dan?
     
  8. Richardthe3rd

    Richardthe3rd

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    There are two types of electric boiler, a Flow Through type & a Storage type. The latter requires a G3 ticket.
     
  9. electronicsuk

    electronicsuk

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    So what's the deal with an electric flow boiler with internal expansion vessel <15l, i.e. an electric system boiler with no DHW storage?
     
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  11. Richardthe3rd

    Richardthe3rd

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    Do you have a link to the product please?
     
  12. electronicsuk

    electronicsuk

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    Elnur CM15 or Elterm Mars series, as these seem to be the only two in the 12-15kW range that can be run on three-phase. If you know of any others then I'd be glad to hear it. Absolutely cannot be single phase, as the supply to the entire building is only 63A/phase.
     
  13. Richardthe3rd

    Richardthe3rd

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    Have you had a look at these?
    http://www.acv.com/gb-en/03_03/18/app.rvb

    Sorry, I've not studied their products too closely but I think they maybe able to help. I take it you're on a commercial cheap tariff?
     
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  14. electronicsuk

    electronicsuk

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    Thanks Richard, I hadn't come across ACV in my searching, though they appear to be more expensive than the other two brands I mentioned previously. I can understand why that'd be the case when compared to the Elterm Mars, which isn't electronically power adjustable or triac controlled, but it seems a pretty similar product to the Elnur CM15.

    As for the tariff, it's a bit of an unusual situation, in that the electricity is free, for the next few years at least, as the costs are included as part of the lease. It would be a bit short sighted to choose electric heating for that reason alone, as power isn't always going to be free, but it's the only source of fuel available. A heat pump would be preferable, but it would have to be air source (it's an upstairs commercial building with no outdoor land), and budget is tight, given that we're talking about an old art-deco cinema that had sat dormant for twenty years, prior to being taken on as a volunteer driven restoration project. That's also the reason for choosing a wet system over direct electric heating, as the original cast iron radiators are going to be refurbished and used again to heat the lobby and bar area.
     
  15. Richardthe3rd

    Richardthe3rd

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    Certainly the tariff is the issue in the long term, so you'd need to establish if there's a cheap rate time for the supply. If you you'd be better looking at a 'Storage' type electric boiler, where the heat can be stored when the cheap tariff is available. Just my 2ds worth, I hope that's some help.
     
  16. electronicsuk

    electronicsuk

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    I would tend to agree, but I'm not sure how practical that would be. Does such a thing as a 15kW wet storage boiler even exist? It would surely have to be huge to retain enough heat to sustain system output during the day. Largely irrelevant anyway, the supply is split from the landlord downstairs, through private metering, so they're stuck with whatever commercial tariff he's running.
     
  17. Richardthe3rd

    Richardthe3rd

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    I'm fairly sure you'd get a >15KW 3Phase Storage type unit, after all Churchill units were fairly common 15-20 years ago. A storage type unit may not be required if your tariff is competitive, so I do think it would be prudent to confirm that before going much further.

    Have you had a heat loss calculation done on the property?

    I hope that's some help, it does sound like a lovely building & hope things go well.
     
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