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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










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  • 0
    Hi folks,


    Just called an electric heating manufacturer to get an idea of instantaneous demand of a typical system. In fact they do supply up to a 14kWatt system for heating and hot water.  The size depends on the heat loss of the flat (no surprises there) but also on water flow rate. If you have a bath then you'll need a sizeable system to cope with the water flow. 


    Now, it transpires that in order to add, say, the 14kWatt device (large flat, 4 bedroom with bath, say), their requirement is a 100 Amp supply at the flat.  Furthermore, the recommended procedure is to install an 80 Amp isolator and run 16mm cable to the boiler.  No small job for one device!  


    From my experience with this particular building all of the flat supplies are 60 Amp fused and their supply cables are 16mm.  So that sets a limit to begin with.  Smaller systems, 9kWatt for example, might be more feasible.


    This, of course, brings us to Mike's latest comment on why we are looking at this as a solution at all.  Well, it seems that one resident has been looking at it and discussed with others.  This travels through the community and we end up with the management committee worried about the power consumption rising to the point where they'll have to pay UK Power Networks extra for fuses and an eventual cable upgrade.  Then I get the call. I'm doing this study pretty much for no charge so far and a general update and education on fuel alternatives is not on my agenda.  That said, if a good critique comes out of this post, I'll be able to go back to them with a better informed opinion.
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  • 0
    Hi folks,


    Just called an electric heating manufacturer to get an idea of instantaneous demand of a typical system. In fact they do supply up to a 14kWatt system for heating and hot water.  The size depends on the heat loss of the flat (no surprises there) but also on water flow rate. If you have a bath then you'll need a sizeable system to cope with the water flow. 


    Now, it transpires that in order to add, say, the 14kWatt device (large flat, 4 bedroom with bath, say), their requirement is a 100 Amp supply at the flat.  Furthermore, the recommended procedure is to install an 80 Amp isolator and run 16mm cable to the boiler.  No small job for one device!  


    From my experience with this particular building all of the flat supplies are 60 Amp fused and their supply cables are 16mm.  So that sets a limit to begin with.  Smaller systems, 9kWatt for example, might be more feasible.


    This, of course, brings us to Mike's latest comment on why we are looking at this as a solution at all.  Well, it seems that one resident has been looking at it and discussed with others.  This travels through the community and we end up with the management committee worried about the power consumption rising to the point where they'll have to pay UK Power Networks extra for fuses and an eventual cable upgrade.  Then I get the call. I'm doing this study pretty much for no charge so far and a general update and education on fuel alternatives is not on my agenda.  That said, if a good critique comes out of this post, I'll be able to go back to them with a better informed opinion.
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