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Electric boilers - effect on power demand of a block of flats

donf
Hello there.


I would like to  know if anyone on the forum has done a study of or knows about an existing study of the impact on power demand of introducing electric boilers to block of flats. 


I have been tasked with estimating the impact of a gradual migration to electric boilers for central and water heating in a modern block of flats. Nearly all of the flats currently use gas fired combi boilers.


I then have to present this information to UK Power Networks so that they can asses whether or not an increase in capacity to the building supply might be needed in future.  Finally I need to put any recommendations to the owners' management board.


Clearly electric boilers will have some impact on power demand.


I can start with an estimate of current power demand (worst case) for a typical flat.  To that end, I'll be doing a survey of about 25% of the flats to come up with a figure.


I can then apply the IET Electrical Installation Design Guide diversity calculations for a typical flat and then the building as a whole using figure 3.4 (IET Electrical Design Guide Nov 2008 page 33).


I can then do a second power consumption exercise adding the demand of a typical electric boiler per flat and then the whole building.


However, it's not clear to me if this approach will be suitable for a massive migration to electric boilers.  I need to be sure of my ground if I approach UK Power Networks with a demand figure.


If we look at the usual peak use of heating demand (morning and evening) a building full of electric boilers, to me, could add a significant load to existing street fuses and possibly even cable capacity.


I would be grateful for any suggestions and experience people could bring.


Kind regards


donf










  • 0
    I had similar discussions with developers.

    They say they want all electric space and water heating, because they have to have an electric supply, but can save on the cost of installing a gas supply. 


    Then they find out how much the upgrade of the DNO network is going to cost and suddenly gas becomes the best option. 


    Don't forget the potentially higher bills will soon dissuade the residents from swapping to electric when they already have gas.


    However I was working in some flats built in the 1980's in the north of Cardiff before Christmas and all the steel gas pipework in and on the building is having to be replaced, so I would ask for some opinions from the gas providers and service engineers as to what the estimated life of the buildings gas pipework is and if applicable the potential cost of replacing it and factor that in.


    Andy Betteridge
  • 0
    Why is the steel pipework being replaced Andy, is it severely rusted or damaged in some way? Steel gas pipework is quite capable of lasting a very long time if suitably protected.
  • 0
    The simplest way to kill this off is to point out that moving to electric boilers will increase the fuel bill by about 3 times and increase the CO2 footprint by the same amount. Just look at the gas and electric prices expressed in pence per kWh.

    Electric heating with heat pumps is about par with gas on cost and CO2 footprint but plain electric is a disaster for the environment and will remain so until the UK marginal generation is wind or solar.

    And don't be fooled by arguments based on renewable tariffs, all they do is rob Peter to pay Paul.

  • 0

    davezawadi:

    Why is the steel pipework being replaced Andy, is it severely rusted or damaged in some way? Steel gas pipework is quite capable of lasting a very long time if suitably protected.




    As far as I know because of corrosion, the flat I worked in has a boiler that packed up over a year ago and the lady has managed with a couple of plug in electric heaters, an electric shower and a kettle since then.


    I hate to say it, but the 80’s were thirty years ago and although I was surprised the gas pipework is being replaced, it is.

  • 0

    Harry Macdonald:

    The simplest way to kill this off is to point out that moving to electric boilers will increase the fuel bill by about 3 times and increase the CO2 footprint by the same amount. Just look at the gas and electric prices expressed in pence per kWh.

    Electric heating with heat pumps is about par with gas on cost and CO2 footprint but plain electric is a disaster for the environment and will remain so until the UK marginal generation is wind or solar.

    And don't be fooled by arguments based on renewable tariffs, all they do is rob Peter to pay Paul.

     




    Given the EPC ratings heat pump are a non-starter even if there is some where to install them.


    Andy Betteridge 

  • 0

    Why is the steel pipework being replaced Andy, is it severely rusted or damaged in some way? Steel gas pipework is quite capable of lasting a very long time if suitably protected.



    I had this discussion with some gas engineers in my previous house when a routine gas meter swap identified low pressure - they told me there's a chemical reaction (not quite rusting, but similar) between gas and the inside of the steel pipework - which produces what looks like rusty sawdust  - and being that this stuff (oxide?) is many times the volume of the steel lost to create it, it gradually clogs up the pipe. Externally the galvanised pipes looked just about perfect. Solution was to dig up the garden and replace the steel pipes with MDPE. The steel pipe they replaced weren't the originals either - there was evidence of a much older gas supply pipe at the other end of the kitchen - presumably dated from when the house was built in about 1938 - which the gas engineers reckoned will have been abandoned for the same reasons. So two generations of steel pipe over 60 or 70 years - perhaps a 30 year service life?


       - Andy.
  • 0
    Plus modern gas combi boilers need more gas.

    Andy B
  • 0
    Steel pipes have come and gone, while black iron seems to just last and last. Unless it is  buried in clay or embedded in concrete. I have had a black iron pipe completely vanish in a concrete floor slab from 1970 or so, but oddly only near a fitting. Once the source of the fizzing bubbles when the floor was mopped were identified, and it was all made safe and we dug it up to see, it transpired that at that point, and pretty much only there, the plastic membrane DPC had been ripped, ironically given the angles, probably by the gas man's Stillsons. Slightly damper concrete, and something in the concrete had pretty much dissolved the iron pipe.

    The street mains are being replaced with polythene because there too, it rusts away to nothing after half a century or so.


    Internal corrosion of steel pipes is related to impurities like water vapour or hydrogen sulphides in the gas, not the methane itself. However A lot of the imported gas we are burning now is not as clean in this respect as the North Sea gas we used to have in abundance. Indeed some of it has to be blended on arrival with the better grade stuff to make it meet the standards for injection into the UK national grid.
  • 0
    Thinking about it and after doing an internet search it commons to mind that a gas fitter explained Microbiologically influenced corrosion to me, condensation and nasties in the gas leading to serious issues.

    https://corrosion-doctors.org/Pipeline/Internal-corrosion.htm
  • 0
    So whilst saying that the electrical networks and equipment may not be up to the standard required to switch from gas to electric, you also need to consider how long the gas network will last without upgrading.


    Andy B.

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