Electric boilers for flats

[Andy78]

Hi all, looking for some advice from those that may have used these products.

A landlord is renovating a building with a large shop on the ground floor and 5no. flats being redeveloped above. As no gas is present they are looking at all electric solutions for the flats.
Their first idea was to have electric shower, electric wall mounted heaters, and undersink water heater for the hot taps. I was thinking that an electric boiler capable of both hot water and central heating provision would be a better option for efficiency and simplicity. Having never provided or installed one however I'm after any advice that can be offered to help me out here. Looking for ideas on brands and any general helpful info.
Thanks

 

[snowhead]

As it's 5 flats the Landlord would be better employing a Consultant or M&E design company to correctly spec the services.
This would also involve weighing up the cost of upgrading the incoming electrical service(s).
This sort of design and spec is not something to be entered into without experience.

 

[Andy78]

As it's 5 flats the Landlord would be better employing a Consultant or M&E design company to correctly spec the services.
This would also involve weighing up the cost of upgrading the incoming electrical service(s).
This sort of design and spec is not something to be entered into without experience.

The landlord is already committed to bringing in a second supply just for the flats and leaving the existing supply to power the shop unit below. He is yet to have a meeting with the DNO to discuss requirements. It's not actually my job, but a friends that I happened to look round with him yesterday.
Just trying to get some ideas of possible ways forward within each flat unit to be able to get some demand figures together.

 

[Deleted member 105166]

It's going to need a chunky supply - five shower circuits alone is >200A and there's unlikely to be much scope for diversity.

 

[ashrow]

Andy

We have installed many electric boilers with rads, UFH and hot water cylinder.
We use a 9kw on smaller jobs and bigger KW boilers for UFH jobs (these are designed and specified by the makers as a free service)
plumber fits everything and then we connect up electrics.
Good thing with having the cylinder is you can also fit an immersion, so they have hot water if boiler fails

Be aware that as manufacture do not like their MCB's running at full load for long periods of time i would now recommend a separate swa submain with HRC fuse (i have had a few 50amp mcbs burn out on 11/12kw and the makers now recommend a 63amp mcb which most makers of domestic single phase boards no longer make.

If you are to have a upgraded electric supply they most likely will not add another to the existing but just put one bigger supply in, as now there must be one means of isolation for the entire installation.
On a 10 block flat we had to have a 400amp supply cost around £25000 as sub station 25 meters away
On a 6 block flat we had a 200amp supply
On a pub and 7 flats we had a 400amp supply cost £47000 as sub station was over 150 meters away

Also i am sure there is electric combi boilers made now so if no room for a cylinder then a combi will do

edited due to poor spelling !

 

[Andy78]

Very useful info @ashrow. Thanks very much ?

 

[Deleted member 105166]

Be aware that as manufacture do not like their MCB's running at full load for long periods of time

@ashrow this is interesting - could you explain this in more detail, as I haven't come across this before. I thought In was continuous with no time implications, provided not exceeded.

 

[richy3333]

If you speak to Heatstore via CEF they are really helpful with possible solutions. With 5 flats depending on size you will need a large supply intake.

 

[James]

Andy

We have installed many electric boilers with rads, UFH and hot water cylinder.
We use a 9kw on smaller jobs and bigger KW boilers for UFH jobs (these are designed and specified by the makers as a free service)
plumber fits everything and then we connect up electrics.
Good thing with having the cylinder is you can also fit an immersion, so they have hot water if boiler fails

Be aware that as manufacture do not like their MCB's running at full load for long periods of time i would now recommend a separate swa submain with HRC fuse (i have had a few 50amp mcbs burn out on 11/12kw and the makers now recommend a 63amp mcb which most makers of domestic single phase boards no longer make.

If you are to have a upgraded electric supply they most likely will not add another to the existing but just put one bigger supply in, as now there must be one means of isolation for the entire installation.
On a 10 block flat we had to have a 400amp supply cost around £25000 as sub station 25 meters away
On a 6 block flat we had a 200amp supply
On a pub and 7 flats we had a 400amp supply cost £47000 as sub station was over 150 meters away

Also i am sure there is electric combi boilers made now so if no room for a cylinder then a combi will do

edited due to poor spelling !

11kw at 230V is 48A
should not be damaging mcb

12Kw at 230V is 52A
long periods of slightly overcurrent will cause damage to anything over time, even if it is not enough to trip the breaker.

it all seems a bit tight, the breaker is to protect the cable, the cable is to supply the load.
if you have a load of 52A why not use a cable rated at 55 or 60A and fuse according to the cable, not the load?

 

[ashrow]

11kw at 230V is 48A
should not be damaging mcb

12Kw at 230V is 52A
long periods of slightly overcurrent will cause damage to anything over time, even if it is not enough to trip the breaker.

it all seems a bit tight, the breaker is to protect the cable, the cable is to supply the load.
if you have a load of 52A why not use a cable rated at 55 or 60A and fuse according to the cable, not the load?

I installed the mcb rated specified by the maker, they have now changed their installation instructions to state a 63 amp (i will try to find the older version and post links etc)
See page 3 of this for kw rating per voltage rating ie https://www.heatraesadia.com/-/medi...lation-manuals/amptec-installation-manual.pdf

The cable i installed are all good for 63amp over the 2 meter run from consumer unit to boiler isolater
Please note i did only install 50amp rated isolators to the installation and none of them burnt out, just the mcb (even with the air gap stated by the makers) this was no loose terminals either the mcb burnt out sideways from the casing

 

[James]

I installed the mcb rated specified by the maker, they have now changed their installation instructions to state a 63 amp (i will try to find the older version and post links etc)
See page 3 of this for kw rating per voltage rating ie https://www.heatraesadia.com/-/medi...lation-manuals/amptec-installation-manual.pdf

The cable i installed are all good for 63amp over the 2 meter run from consumer unit to boiler isolater
Please note i did only install 50amp rated isolators to the installation and none of them burnt out, just the mcb (even with the air gap stated by the makers) this was no loose terminals either the mcb burnt out sideways from the casing

I am not judging you.
manufacturers guidance should be good.
they have presumabley had problems so updated there guidance.
as I have mentioned before in other posts, over spec. is better than under spec.
going close to the line often involves being called back.

 

[ashrow]

@ashrow this is interesting - could you explain this in more detail, as I haven't come across this before. I thought In was continuous with no time implications, provided not exceeded.

Working on finding where i read this, will post back when i find it
[automerge]1570215142[/automerge]

I am not judging you.
manufacturers guidance should be good.
they have presumabley had problems so updated there guidance.
as I have mentioned before in other posts, over spec. is better than under spec.
going close to the line often involves being called back.

@ashrow this is interesting - could you explain this in more detail, as I haven't come across this before. I thought In was continuous with no time implications, provided not exceeded.

https://www.tlc-direct.co.uk/Technical/DataSheets/Wylex/WylexNsMcb.pdf

The NS single pole MCB with its Type B characteristics is suited for general domestic ... recommend a 66% diversity factor is applied to the MCB nominal rated current where it is intended to load the MCBs continuously (in excess of 1 hour). ... WYLEX NS RANGE MCB INTERNAL VIEW. Maximum prospective fault current.

 

[dmxtothemax]

I know from experience that running electrical gear close to or at maximum ratings is a recipe for short life, count on it !

 

[telectrix]

pal of mine ..new build. no gas. i insisted he had 3 phase installed, and fitted a 3 phase boiler. would have bee 65A on single phase, but on 3 phase it was down to 22A per phase. manageable. he winged about the extra cost of supply £5K single phase, 7K 3 phase. now he's over the moon and i'm his favorite guy.

 

[Zerax]

pal of mine ..new build. no gas. i insisted he had 3 phase installed, and fitted a 3 phase boiler. would have bee 65A on single phase, but on 3 phase it was down to 22A per phase. manageable. he winged about the extra cost of supply £5K single phase, 7K 3 phase. now he's over the moon and i'm his favorite guy.

How many guys does he know ?