14Kw Electric Boiler

[Chrisknowlesuk]

I would like some advice please.

A friend of mine has moved into a small flat. There is no Gas supply to the property and so is looking into having a 14Kw Boiler installed. This would require a 63A breaker on the board. My calculations for Maximum Demand based on the other circuits in the property comes to approx 95A.

She has no access to the meter as it is situated in the neighbours flat across the hallway - they are currently away travelling. Although, based on the probable age of the flat I would expect it only has a 60 or 80Amp fuse on the supply. And would therefore need upgrading.

Since this will present a whole load of issues I just wanted to make sure I am thinking along the right tracks and if anyone had any good ideas please??

Thanks

Chris

 

[brianmoooore]

My calculations for Maximum Demand based on the other circuits in the property comes to approx 95A.

Care to share them?

 

[Chrisknowlesuk]

Care to share them?

I am trying to find the spreadsheet that I used to calculated them.

It was something like;

Electric Boiler 63a x 100% = 63A
7Kw Cooker after diversity applied - 21A x 40% = 8.4A
Kitchen ring 32A x 40% = 12.8A
Ring main 32a x 40% = 12.8A
LED lights (60w) negliible

Total current demand - 97A

 

[brianmoooore]

Ah! You were including the boiler in that calculation. Your OP reads (to me, at least) that you were calculating 97A without the boiler.
My calculations for diversity wouldn't be quite the same as yours, but I wouldn't end up with a figure much different, so, yes, there are likely to be issues with an old supply.

 

[littlespark]

Having your meter in someone else’s property doesn’t sound like a good arrangement.

There may be additional controls that come with the boiler where it cuts out when, say, the cooker is on.

 

[Chrisknowlesuk]

Having your meter in someone else’s property doesn’t sound like a good arrangement.

There may be additional controls that come with the boiler where it cuts out when, say, the cooker is on.

Yes it is a bit of a mess and I'm not sure why it wasn't picked up during the survey? (it is a friend of mine). They should have had an EICR which would have highlighted it straight away.

 

[Chrisknowlesuk]

Ah! You were including the boiler in that calculation. Your OP reads (to me, at least) that you were calculating 97A without the boiler.
My calculations for diversity wouldn't be quite the same as yours, but I wouldn't end up with a figure much different, so, yes, there are likely to be issues with an old supply.

Yes sorry that is with the boiler.

However, it has occurred to me that the boiler they are thinking of getting is perhaps more powerful than they need? It is only a 1 bed second floor flat. So 5 rads max plus hot water for kitchen and bathroom. I'm thinking now that their best solution would be to look for a smaller unit (perhaps 8/9Kw) which brings it within the load for the current supply.

I don't know what supply fuse they have, but they showed me a photo of the meter that the previous owner had, which had 80A rating on the meter - but would that necessarily mean an 80A supply fuse??

 

[brianmoooore]

14kW is probably well over the top for the heating load, but I wouldn't want to be dependant on much less for instant water heating. Ever tried catching water in a pan from even a 10kW electric shower? Takes a while to fill.

 

[Zerax]

I would question the cost of running such a system... I also have a small flat (it's actually 2 bed) that has no gas and is entirely electric. My setup is a hot water cylinder, then panel heaters in each room. I'm on the Octopus Go tariff so I have the 4 hrs per night at 5p/kWh (as of now, but I'm sure this will be going up soon) which is when I heat the water. The panel heaters are used as and when required and total 7 x 750W... but I never have them all on... the two bedroom ones are on rarely, and the bathroom one mostly when it's being used, else it's very low. So it's more like 3.5 kW heating load... but only when it's heating from cold... else it cycles.

I think having a wet system removes one of the main benefits of electric heating... in that it's super controllable (if setup and designed to be) unlike radiators usually are.

If I were your mate... I'd be looking at the possibility of installing an air to air heat pump... parts are about £1k + install (if he can get permission for a 2nd floor flat)... far more interesting and cheaper to run

 

[snowhead]

Where did the 14kw idea come from?

The first thing to do, is to get an accurate assessment of the heat loss of the flat done by a professional and the suitable size of boiler to heat it.
That professional should also be someone who can advise install costs and running costs of suitable heating systems, not just boiler and wet systems so would probably not be a Plumber / Heating engineer.
And would also include any heat saving measures that could be done to reduce the load / running costs.

Sometime / somewhere along the way depending on whether it turns out to be an electric boiler or not and the supply needs upgrading, the meter needs moving to an accessible location.

 

[brianmoooore]

Where did the 14kw idea come from?

The first thing to do, is to get an accurate assessment of the heat loss of the flat done by a professional and the suitable size of boiler to heat it.
That professional should also be someone who can advise install costs and running costs of suitable heating systems, not just boiler and wet systems so would probably not be a Plumber / Heating engineer.
And would also include any heat saving measures that could be done to reduce the load / running costs.

Sometime / somewhere along the way depending on whether it turns out to be an electric boiler or not and the supply needs upgrading, the meter needs moving to an accessible location.

As above, and also needs provision for some kind of stored hot water system. Can be a small cylinder with just 2kW loading, or can be bigger if it's wired to have priority over the heating.

 

[Rockingit]

Just a thought...... if it were me, I'd be looking along the lines of modern 'smart' panel heaters and under-counter water heater/s. Way more cost effective in the long run and no pipes! And also no need to pay hundreds to the DNO (even though I actually think you'd be fine). However - unaccessible meter is not very clever.

 

[brianmoooore]

Just a thought...... if it were me, I'd be looking along the lines of modern 'smart' panel heaters and under-counter water heater/s. Way more cost effective in the long run and no pipes! And also no need to pay hundreds to the DNO (even though I actually think you'd be fine). However - unaccessible meter is not very clever.

Don't forget there's no diversity on water heaters, so if you fit two, you double the design load. Capacity of the water heater depends to some degree as to whether there's a bath in the flat. If there is, it needs to be able to fill it in one hit.

 

[Rockingit]

Don't forget there's no diversity on water heaters, so if you fit two, you double the design load. Capacity of the water heater depends to some degree as to whether there's a bath in the flat. If there is, it needs to be able to fill it in one hit.

Yes, ish, except in practice what we're achieving is dropping a load down from 14kW for hot water down to at a guess 6-7. And the panels all become hundreds of Watts individually, not thousands as a whole system. Besides, beyond all of that, does away with Mr WetPants Plumber which has to be far more important.

 

[Chrisknowlesuk]

I would question the cost of running such a system... I also have a small flat (it's actually 2 bed) that has no gas and is entirely electric. My setup is a hot water cylinder, then panel heaters in each room. I'm on the Octopus Go tariff so I have the 4 hrs per night at 5p/kWh (as of now, but I'm sure this will be going up soon) which is when I heat the water. The panel heaters are used as and when required and total 7 x 750W... but I never have them all on... the two bedroom ones are on rarely, and the bathroom one mostly when it's being used, else it's very low. So it's more like 3.5 kW heating load... but only when it's heating from cold... else it cycles.

I think having a wet system removes one of the main benefits of electric heating... in that it's super controllable (if setup and designed to be) unlike radiators usually are.

If I were your mate... I'd be looking at the possibility of installing an air to air heat pump... parts are about £1k + install (if he can get permission for a 2nd floor flat)... far more interesting and cheaper to run

Thanks for the detailed advice.

I've just gone to the flat below where all of the meters are. The meters have a 60Amp fused isolator box which has a thick armoured cable that goes up and away into the flat, but its hard to identify what size this is??

It doesn't give much head room at all for electric options.

I'll look into the air to air heat pump.

Thanks

 

[brianmoooore]

Besides, beyond all of that, does away with Mr WetPants Plumber which has to be far more important.

I have the advantage on you there! I kicked Mr Wetpants out of the door 40 years ago or so, and donned his hat, alongside my sparky's one. Never had to put up with one since, (except for one couple month period, that I wrote about on here recently.)
Can't see the point of electric boilers into wet radiator systems, without any kind of thermal store, except, I suppose, if a serviceable
wet system is already present.
Could be an advantage if you have access to significantly cheaper off peak electricity, and can use the boiler to dump heat into a thermal store and/or thick slab wet UFH.

 

[Chrisknowlesuk]

I've just seen some of the posts to the thread.

The 14Kw size came from her relatives who do bathroom fitting (but not boilers). Having looked into it a bit myself, it does seem very over spec'ed for a small flat.

The owner of the flat on the ground floor let me in to look at the meters etc this evening. It is in a cupboard which may have been a communal area once upon a time perhaps which houses a very big grey box where I presume the supply is split then it goes to the meters for all three flats, split in each case to 60Amp isolators for Day and Night tariffs and a fat armoured cable leading up and away to the respective flats.

Fortunately, the tenant seems very accommodating but I would hate to think of the cost implications to get it all moved...

Hopefully, if the supplier can upgrade the meter that would be a start. Then I suppose the armoured cable going up to the flat would need to be changed?

Perhaps, if an EICR had been asked for before buying then this would have all been discovered and choices made before committing to the purchase?

 

[Sharlene]

Where did the 14kw idea come from?

The first thing to do, is to get an accurate assessment of the heat loss of the flat done by a professional and the suitable size of boiler to heat it.
That professional should also be someone who can advise install costs and running costs of suitable heating systems, not just boiler and wet systems so would probably not be a Plumber / Heating engineer.
And would also include any heat saving measures that could be done to reduce the load / running costs.

Sometime / somewhere along the way depending on whether it turns out to be an electric boiler or not and the supply needs upgrading, the meter needs moving to an accessible location.

What kind of professional that do the type of assessment and provide the advice you mentioned here please? We are about to renovate our property and need to choose the right central heating system, so we are really interested to know, thank you.

 

[brianmoooore]

It's not an exact science, whoever does the assessment, but it's not that difficult to work out for yourself, with a little research and use of simple arithmetic.
Look up how to design the requirements for a central heating system. It involves dividing your house into 'elements', working out the heat loss for each, then adding them all together. The 'elements' are each external wall for each room, any openings in that wall, such as doors and windows, the floor of that room, if a ground floor, and the ceiling of a top floor room, then there is an additional allowance for air changes in that room. You need to know the construction of each element, to access its insulation (u) value, and the required temperature difference either side of it.
Once you've worked out and added up all these 'elements', you have the heating requirement for the property, against the outside temperature that you chose (usually -1 degree). The final figure is then that figure, plus at least 10%, but it's generally a good idea to add on around 30% to ensure comfort in the worst weather.
I've always done these calculations as above, but I'm sure there are many online calculators or even apps. available today to do the arithmetic for you.

 

[partplonker]

14kW is pretty much the biggest size that electric boilers come in. There are smaller 6kW or 9kW ones available that might be more suitable for this property.

What Size Electric Boiler do I Need? | Boiler Guide

Electric boiler size is measured in kilowatts & installing one that’s too powerful will increase energy bills. Find the right electric boiler for your home.

www.boilerguide.co.uk

As others said, if there isn't wet central heating in there already (or it needs a lot of work), it might be more cost effective to use storage radiators and/or underfloor with small on demand water heaters for the bathroom and kitchen.

(edit: I just noticed that this thread is a month old but can't delete my comment now ...)