Electric Boilers: Reliable and cost effective?

[Raks]

Hi;
For a converted small studio, I can't put any gas combi because of the lack of space and gas supply.
Is the electric combi boilers like STORM (https://www.screwfix.com/p/strom-sbsp15c-single-phase-electric-combi-boiler/655hr) good alternative?
or is it better to have separate electric shower and electric radiators and a small unvented water heater for kitchen?

or is this multiport system good enough to supply hot water and shower? ( https://www.toolstation.com/strom-11kw-touch-instantaneous-water-heater/p78066?utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gclid=EAIaIQobChMI2oTorr3a5QIV0-R3Ch3o1wvUEAkYBCABEgIfG_D_BwE )
How are the alternative solutions compared by running cost, reliability wise.
So which electric boilers/heaters would you suggest for hot water, shower and heating for a small studio?
Thanks

[Moonshine]

As gas seems to be on the way out for environmental reasons, i am half wondering even though there is a potential gas supply to one of my plot, whether to not bother getting the connection, and just have electric with an electric boiler and decent electric hob cooker (i love cooking on gas hobs as electric ones seem to be pants).

 

Therefore i am interested in what the latest is with electric boilers are, do they heat water for the central heating system as well, or would having gas free house mean having electric radiators in each room?

 

Also there would be no flue required, which could make it much more flexible where it could be placed.

 

So, to add to the OP, Electric boilers, cons?

Edited November 8, 2019 by Moonshine

[SteamyTea]

22 hours ago, Moonshine said:

i love cooking on gas hobs as electric ones seem to be pants).

You have not used an induction hob then.

23 hours ago, Raks said:

or is it better to have separate electric shower and electric radiators and a small unvented water heater for kitchen?

It is always better to separate space heating and hot water. They do different things, at different times, and at different temperatures.

 

During this renovation can you put in underfloor heating?

[Raks]

24 minutes ago, SteamyTea said:

During this renovation can you put in underfloor heating?

 

yes I am considering UFH for the kitchen and entrance hall but not sure how effective they are for the bedrooms as there is not much floor space after the furniture and bed.

Actually I was considering to use one of these between joist UFH spreader plate systems but again have to see if they are good enough as there will be no screed on top for thermal storage, just the hot pipes, spreader plates and on the top, floor finish. (i think better to use tiles instead of hardwood as finish)

 

My previous related topic and link for UFH:

https://www.theunderfloorheatingstore.com/confused/water-underfloor-heating-for-between-joists-or-suspended-floors

 

 

[SteamyTea]

Using mass as storage is really just a way to either time shift when you put the energy in, which may save cash, or to stabilise output temperature, or both.

When normal radiators are put in, I have never heard it mentioned that they lack mass, and people see quite happy that they have an area of wall that is, in effect, unusable because there is a hot emitter there.

 

It is really just down to doing some simple heat loss calculations  and then finding a cost effective solution.

@TerryEuses UFH and a very simple inline, resistance element. He can explain more about it better than me.

 

[Big Jimbo]

The 11kw instantanious heater delivers about 6.2 lt of water a min. Not sure at what temp ??? In a small studio i would have thought that for a kitchen sink, toilet sink, and shower that would be ok as long as you are not using all the outlets at once. A power shower it ain't gonna be. I think my temp shower is 10.? kw and it has done the job for the passed Two years. Not a patch on my 18lt a min power shower in my last place.

[SteamyTea]

24 minutes ago, Big Jimbo said:

The 11kw instantanious heater delivers about 6.2 lt of water a min

My shower delivers at 11 lt/min, it is nice.  Probably get away with 9 lt/minute.

 

[Big Jimbo]

2 minutes ago, SteamyTea said:

My shower delivers at 11 lt/min, it is nice.  Probably get away with 9 lt/minute.

 

So 6.2 will be like getting P1553d on

[SteamyTea]

Just now, Big Jimbo said:

P1553d

Yes, and if the water temperature is low, it will flow even less.

[Big Jimbo]

Same as me in the middle of the night when it is freezing

[ProDave]

For anyone considering electric heating, you should look at Air Source Heat Pumps rather than resistance heating.  For every KW of electricity they use, you get between 3 and 4 KW of heat.

[SteamyTea]

12 minutes ago, ProDave said:

For anyone considering electric heating, you should look at Air Source Heat Pumps rather than resistance heating.  For every KW of electricity they use, you get between 3 and 4 KW of heat.

Does rely on having room for it, and a thermal store.

There are some relatively small, wall mounted air to air heap pumps, that could be good enough for a small place.

It may be able to fit them in with oversized MVHR, but again, in a small house or flat, probably not enough room.

[ProDave]

1 minute ago, SteamyTea said:

Does rely on having room for it, and a thermal store.

There are some relatively small, wall mounted air to air heap pumps, that could be good enough for a small place.

It may be able to fit them in with oversized MVHR, but again, in a small house or flat, probably not enough room.

Unless you have no outside space, then there should be somewhere to put one.

 

A hot water tank, that is the only significant inside bit should fit in not a lot more space that the OP was proposing for an electric boiler.

[Raks]

24 minutes ago, ProDave said:

For anyone considering electric heating, you should look at Air Source Heat Pumps rather than resistance heating.  For every KW of electricity they use, you get between 3 and 4 KW of heat.

maybe this could be an other topic but I have no idea about heat pumps. Are the air source heat pumps powerful enough to use as the main heating source of a house (DHW and heating) or are they good as a secondary source to support main the gas/electric heating system  of the house?  (say for a 3 bed detached house in London/UK)

Edited November 8, 2019 by Raks

[ProDave]

1 minute ago, Raks said:

maybe this could be an other topic but I have no idea about heat pumps. Are the air source heat pumps powerful enough to use as the main heating source of a house (DHW and heating) or are they good as a secondary source to support main the gas/electric heating system  of the house?  (say for a 3 bed detached house )

Yes if sized correctly. It depend how much heat the house needs (how well insulated)  Our 3 bedroom detached house is using a 5KW air source heat pump for heating and hot water.

[Temp]

14 hours ago, Raks said:

How are the alternative solutions compared by running cost,

 

Standard (eg daytime) electricity is roughly four times the cost of mains gas. Scroll down this page to the table..

 

https://nottenergy.com/resources/energy-cost-comparison/

 

So an electric ASHP (heat pump) with a COP of 4 gets you back to the same ball park price as mains gas.

 

Ok so maybe possible to get a better electricity deal than assumed by the Nottingham web site but you get the general idea.

[PeterW]

22 hours ago, Raks said:

Hi;
For a converted small studio, I can't put any gas combi because of the lack of space and gas supply.
Is the electric combi boilers like STORM (https://www.screwfix.com/p/strom-sbsp15c-single-phase-electric-combi-boiler/655hr) good alternative?
or is it better to have separate electric shower and electric radiators and a small unvented water heater for kitchen?

or is this multiport system good enough to supply hot water and shower? ( https://www.toolstation.com/strom-11kw-touch-instantaneous-water-heater/p78066?utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gclid=EAIaIQobChMI2oTorr3a5QIV0-R3Ch3o1wvUEAkYBCABEgIfG_D_BwE )
How are the alternative solutions compared by running cost, reliability wise.
So which electric boilers/heaters would you suggest for hot water, shower and heating for a small studio?
Thanks

How big is the studio and how often will it be used ..?? 
 

Also, how well insulated is it ..?

 

I would go with a small under sink unit feeding kitchen sink and basin in the bathroom, and a decent 10kw electric shower.

 

For heating I would swap to a split air con unit that can do both heating and cooling, and an electric towel rail in the shower room to keep that warm. If you stay away from cold tiles and go with a vinyl/Lino type product for the bathroom too, then tile heating wouldn’t be required. 

[PeterW]

22 hours ago, Moonshine said:

As gas seems to be on the way out for environmental reasons, i am half wondering even though there is a potential gas supply to one of my plot, whether to not bother getting the connection, and just have electric with an electric boiler and decent electric hob cooker (i love cooking on gas hobs as electric ones seem to be pants).

 

Therefore i am interested in what the latest is with electric boilers are, do they heat water for the central heating system as well, or would having gas free house mean having electric radiators in each room?

 

Also there would be no flue required, which could make it much more flexible where it could be placed.

 

So, to add to the OP, Electric boilers, cons?

Up the insulation and drop the heat demand and then you need to load shift as per @SteamyTea to get the loads onto E7 or at worst E10. 
 

Concrete slab as mass storage, then you may find you can even get away with a Willis type arrangement. I’ve seen inside an electric boiler thanks to @newhome and it’s basically a 3 phase immersion with a set of triac drivers - one per phase - that brought in individual 6kw immersion elements. Nothing fancy but not cheap for what is in effect a big Willis heater. 
 

You could very easily daisy chain 3 Willis heaters together to get 9kw and use an off the shelf PID controller to manage the lot for change of £150 if you really needed that sort of heat input into a slab and don’t want an ASHP. 

[Nickfromwales]

58 minutes ago, PeterW said:

Up the insulation and drop the heat demand and then you need to load shift as per @SteamyTea to get the loads onto E7 or at worst E10. 
 

Concrete slab as mass storage, then you may find you can even get away with a Willis type arrangement. I’ve seen inside an electric boiler thanks to @newhome and it’s basically a 3 phase immersion with a set of triac drivers - one per phase - that brought in individual 6kw immersion elements. Nothing fancy but not cheap for what is in effect a big Willis heater. 
 

You could very easily daisy chain 3 Willis heaters together to get 9kw and use an off the shelf PID controller to manage the lot for change of £150 if you really needed that sort of heat input into a slab and don’t want an ASHP. 

Why make it so complicated?

Willis heaters go in, paralleled up in qty to match max heat demand + 50%, on a recirculating loop ( or through a small low loss header for a very small dwelling ), and just let the dwelling suckle heat from that loop as it wants. Call for heat kicks in the heaters, and they go off or into 'satisfied state' until the recirculated water temperature drop low enough for the willis stat to kick back in.

Done a few like this recently where there was no gas, no room ( or desire ) for an ASHP, and low / infrequent demand. Works really well.

23 hours ago, Raks said:

So which electric boilers/heaters would you suggest for hot water, shower and heating for a small studio?

Keep it simple here

 

Heating;

Electric panel radiators are cheap as chips, and will heat the place almost instantly / on demand, and are very well suited if infrequent use is typical. Something as small as ~2kW units ( x2 for even spread of heat if more of a spread of heat is necessary ) which will kick in / out thermostatically as required. I'd buy the ones that have separate wall mounted wifi room stats / timers for ease of control & to prevent overheating the space aka economic running. These can run off 13a plugs with no special needs for a big electricity supply. Forget UFH unless you go for an ASHP, but that would seriously have to be justified by the usage of the dwelling mandating such a complex and costly setup? What is it's intended long-term use?

 

Hot water;

Fit a size 6 Uniq ( Sunamp ) and you'll only need a 3kW electric supply to get high pressure DHW on a 22mm supply   That will tee off to do basin / sink / shower from one source and no need for a discharge pipe and G3 annual inspection. Note: the Sunamp isn't a hot water tank it's an instant water heater / thermal store, so no actual 'stored water' to speak of. Next to no losses in comparison to an UVC, and a far, far more simplified installation with prob half the space or less taken up. It'll go into a kitchen unit as its only ~580mm deep x ~370mm wide x ~650mm high. Near zero maintenance too, as its only requires a single tiny expansion vessel that can be checked in minutes ( by anyone who's competent to do so ).

 

Electric boilers, and even worse electric combi's are very electricity hungry. If you had an electric boiler and a big electric shower you'd need a big electricity supply to match. Fit a big electric shower and it'll also be massively dependant on cold mains pressure / flow rate. It will suffer to a point that it's useless if anything is running off the same cold mains supply ( in the main building ) at the same time, and you'll end up running it on it's lowest setting most of the time just to get a decent stable temperature out of it. God help you if someone goes to use the kitchen sink whilst you're in the shower!!! The only way to combat that issue is with a 100-200L cold mains accumulator, which is a BIG vessel to try and integrate into somewhere where space is already tight.

[SteamyTea]

1 hour ago, Nickfromwales said:

 

Heating;

Electric panel radiators are cheap as chips, and will heat the place almost instantly / on demand, and are very well suited if infrequent use is typical.

Trouble is that in a small home, you loose wall space and floor area.

Why I took the panel heaters out of the bedrooms, they limited were I could put the beds.

[Nickfromwales]

34 minutes ago, SteamyTea said:

Trouble is that in a small home, you loose wall space and floor area.

Why I took the panel heaters out of the bedrooms, they limited were I could put the beds.

They can go behind furniture without issue. They heat by convection rather than radiation, so no problem not 'seeing' them .

Fit multiple smaller ones to get the required heat and fill any available 'gaps' to suit the room layout.

Number one rule; DON'T put them on outside walls wherever possible.

[SteamyTea]

2 minutes ago, Nickfromwales said:

Number one rule; DON'T put them on outside walls wherever possible

I don't think you realise just how restricted a badly designed, 48 square metre, 2 bed, terraced house can be.  Even windows get in the way.

 

[Nickfromwales]

3 minutes ago, SteamyTea said:

I don't think you realise just how restricted a badly designed, 48 square metre, 2 bed, terraced house can be.  Even windows get in the way.

 

Fortunately I spent about 13 years fitting new heating systems into exactly these types of properties   We had to get very inventive of how to get heat into these and often the only way to get sufficient heat output was to fit two smaller radiators in the same room wherever there was room to do so.

UFH in a retro fit is bloody hard to get right, even harder to insulate against the losses from, and are utterly impractical in small rooms with lots of furniture. The capital cost and impact to living pattern vs heating use is also a huge PITA.

Horses for courses  

[SteamyTea]

14 minutes ago, Nickfromwales said:

Horses for courses

I agree, but if we constantly keep bodgeing and compromising, we will get nowhere.

Sometimes, we just have to bite the bullet and do the right thing.  Often too much emphasis is put on price and not what is best for the occupants.

[Nickfromwales]

Putting convection heating into a retro fit is in no way whatsoever a bodge my old china mug  

If the occupants are in a tiny 2 bed terrace, there's a bloody good reason for it! UFH and an ASHP really need to be designed in at the outset. Lipstick on a pig and all that eh?