Gas to electric boiler - which type?

steesw

I have a gas combi boiler, with a concealed flue that I've been told should be replaced with an electric system as it's not really possible to move the boiler/flue. I've had a few people quote different electric set ups, but can't tell which would be the best option:

• Direct acting boiler - e.g. Elnur Mattira MAC15 combi
• Storage system - e.g. Potterton heat only + 150L water tank

From what I've gathered from online searching, storage systems typically cost more to install but then have lower running costs, but when I've had companies quoting for both types it's been the direct acting system that costs substantially more to put in, and they claim it's more efficient to run... There also doesn't seem to be much agreement on which has the better lifespan/reliability!

I'd be grateful for any advice on which way to go! It's for a 1-bed, 1 bath flat with water underfloor heating.

alleycat`

Is there a restriction on access to the flue? As far as i know the Regs were only updated saying that full inspection must be possible.


If it's possible to put inspection hatches in i'd assume a gas boiler would still be much cheaper to operate.


I know that's not really your question but where possible / safe / meets Regs i'd be looking to do that.

steesw

Hi alleycat, thanks for your message. The flue goes upwards through the flats above and as far as I’m aware they didn’t put inspection hatches in unfortunately.

macman

Any type of electric boiler is going to triple your energy bills, so you really do need to investigate all the options to retain your gas combi system.
A storage system might enable you to heat a tank of hot water on cheap rate E7, but that will be more than cancelled out by the higher cost of space heating during the day/evening on E7 peak rate.
In a small flat, you would be better off reverting to an immersion heater and NSH's if you cannot retain the gas combi.

Autumnella

I would look into the possibility of having the boiler moved. Electric heating systems cost a fortune to run.

Owain_Moneysaver

Instant electric heaters are limited to about 10 kW due to the loading on the supply. The Elnur Mattira MAC15 is limited to 12kW on a single phase supply.

That will be very very very very slow filling a bath. Whether it's suitable for your wet underfloor heating depends on the heating load and in particular how well your floor is insulated.

It could turn out to be very expensive to run.

If you want to fill a bath quickly you will need a hot water storage cylinder. That combi will produce a shower, but so will an electric instant shower for less than £100.

If you feel you must continue with wet underfloor heating I'd be looking at a vented thermal store on Economy 7, where a large tank of hot water stores the heat. The other option is to move to storage heating.

steesw

Thank you everyone for the advice, this is really helpful! I’ll see if it might be possible to move the boiler flue - I think not because there’s only one external wall which is mostly windows - but if not it seems like a water cylinder might be the best option.