Electric boiler solution

[purplemonkey23]

hi all,


I'm building a smaller flat in the front of my property with the intent to rent it out. I am able to run the ho****er and heating from my existing gas boiler, but I want to consider the alternative.
I don't want to use gas in this new flat, so electric is the way to go, however I'm having a hard time understanding electric boilers. It appears in most cases you need to have a hot water tank! and unfortunately I don't have any room for a hot water tank.


So far I can only see it working this way.(all models are for example only, none have been choosen yet)
1 long thin boiler to run my central heating system. (EHC Slim Jim 10KW Electric Flow Boiler)
1 electric shower unit to run the shower. (Triton Enrich Manual Electric Shower White 8.5kW)
2 under sink water 15l tanks (Ariston Europrisma 3kW 15Ltr Usink Water Heater) for kitchen and bath sink.


this seems like a real ball ache, especially the sink units. is there no simple Gas Combi boiler alternative?


Its unfortunate but the flat doesn't have any extra space for large water tanks, a gas combi could go in the kitchen, but all this electric alternative equipment looks like it'll take up a lot of space! And probably cost a damn fortune to run.


ideas or info would be much appreciated, cheers.

 

[Ray Stafford]

Hi Purplemonkey

Your proposed solution will work, although I feel very sorry for your tenants, whose energy bills will be excessive.

Its an issue that comes up on this forum every few weeks, but no, there is not an electric version of a gas combination boiler that a) avoids storage and b)delivers anything like a useful flow rate.

If you look at a gas combi, outputs start at 24kw and rise from there. This is because 24kw is the minimum input required to get even a modest flow-rate at a decent temperature rise in an instantaneous water heating appliance. Single phase domestic electric supplies top out at approx 11kw - you would need a commercial 3 phase installation to get 24kw.

Is your motivation regarding avoiding gas simply to avoid having a safety certificate? If so, put the rent up a bit - the pain you are going to cause your tenants in energy bills is an order of magnitude greater than the cost of getting a GSR in once a year.

 

[townfanjon]

Good advice from Ray ^^

Imo, a flowboiler and small unvented cylinder is the only way to go.

 

[purplemonkey23]

Thanks Ray that's a very informative post, I do have energy usage as a requirement, so I wouldn't just want to increase bills. Its just hard to find quality advice that explains the electric boiler problems. I also appreciate its more complex then a simple kw comparison, do you know of any good documentation or studies that have been done to show actual cost differences?

I do have lots of smaller eve space but the smallest water tanks are far too large to fit, do you know if anyone does a shorter wider hot water tank?

cheers.

 

[Ray Stafford]

Thanks Ray that's a very informative post, I do have energy usage as a requirement, so I wouldn't just want to increase bills. Its just hard to find quality advice that explains the electric boiler problems. I also appreciate its more complex then a simple kw comparison, do you know of any good documentation or studies that have been done to show actual cost differences?

I do have lots of smaller eve space but the smallest water tanks are far too large to fit, do you know if anyone does a shorter wider hot water tank?

cheers.

There's some data here on the cost per kw/h for various fuel types.

The two big variants are the mix of full tariff and reduced tariff (E7, E10 etc) on electricity prices, and the degree of standing losses from stored water vs instantaneous. If the property is likely to be rented to a permanent tenant, then stored water using reduced tariff leccy usually works out a lot cheaper. If its a holiday let, the maths changes depending on occupancy ratios.

If you have eaves space, have a look at horizontal cylinders, which, as the name suggests, lie like a torpedo, rather than standing up like a rocket. There are also Fatmax cylinders which are shorter and dumpier, but probably not sufficiently so to fit in an eaves space.

 

[purplemonkey23]

Thanks again Ray.
The flat is to be let as a holiday, short term let, and I'll be feeding hot water(&heating) from my gas boiler for this purpose. I want to preempt the possibility of letting more permanent in the future, and for this I want to plumb ready the flat for a new boiler system switch over in the future, without the need to ripping out the finishings.

Thanks for the Torpedo info, looking into them now.