9kw Ferroli Electric Boiler

[nightmareflat]

Hi,

Under the advice of my builder I replaced the gas combi boiler in my flat with an electric 9kw ferroli boiler + an immersion heater tank.

It's a 2 bed 900sqfoot flat with 3 large radiators and 2 small ones.

As expected, the electric bills are ghastly. I've had double glazing installed and I've had reflective foil installed behind all of the radiators. Even still, I'm finding the heating bills to be crazy in the winter, sometimes £15, £20, £25, £30 per day of electricity being used.

In my old new build flat, similar size, similar number of radiators, there was a 4kw potterton gold vertical boiler which never had any problems and the flat heated fine.

Would it be a bad idea to remove the 9KW boiler and replace it with a 4KW one?

My understanding was that the boiler shouldn't always be drawing on the full 9KW load when in use but it doesn't seem to be the case which is why I'm inclined to switch to one that will use less electric (though it might take a little longer to heat up the radiators).

Is it also worthwhile getting one of those little booster things installed at the same time ?

Thanks.

 

[ericmark]

Size of boiler will not help, water storage size may, assuming some off-peak supply, and swapping type of off-peak supply.

I use an off-peak supply to charge the batteries got for the solar panels, and was surprised to see such huge variation in off-peak rates. With the EV tariff being a lot cheaper to the economy 7 tariff. There is also economy 10, and huge difference between suppliers, not only on price, but what they will let you have.

British Gas gave me an EV tariff, 5 hours at 8.95p per kWh, looked at Octopus and the tariff is far better, but would not allow me to have it without an EV, and each area is also different.

Basic idea is in real terms likely twin tanks, but the idea is multi-fuels can be used, and it stores some heat, one I looked at had two massive 80 gallon tanks. This could store around 26 kWh of power, which is unlikely to be enough on really cold days, to span 19 hours. So one works on an average, but you have to work out when to use what.

I have the same problem with my simple solar panels, put tumble drier on, but at moment still exporting 3 kW which is not what I want to do, had I used less off-peak than would not be exporting now.

So easy to become a slave to the solar panels, and it is the same with any stored energy, when to store, when to use, and is all the faff around worth it, we can look at how much energy from heat pump, at what point to stop using heat pump and use immersion heater, etc, etc. But add installation cost, and specially the control system, not to mention the room or any reinforcing of the floor to take the weight, and you see how the heating and ventilation engineer earns his money.

I will admit my errors, many will not, last three homes, I made mistakes, in the main selection of thermostat, there are two ways to heat the home, 24/7 or only as and when required. Heat pumps with 24/7 work well, as does underfloor heating, but as required, recovery time is the buzz word, the fastest way to heat the home is inferred, but that has control issues, so next is fan assisted radiators, there is a noise issue, but the new ivector with 5 speed fans gets rid of most of that, but then also the installation cost. So most of us use near enough engineering, and the simple panel radiator, these lend themselves to control with TRV's and linked programmable TRV heads, but at around £60 a pop, back to what is worthwhile.

So when one starts to look at cost, is it getter to get rid of electric and move to gas or oil, at 73 I think my system will pay for its self just about in my lifetime inshallah, but only if I remain here, if I go into an old peoples home, then will not pay for its self.

So the question is if it is worth it? My flat in Hong Kong had simple stand-alone air conditioning units which both heated and cooled, mainly cooled, and there is a good point in "keep it simple silly" do we really need a complex system in a simple flat?

 

[nightmareflat]

Sorry, forgot to add.

It's a leasehold flat so I can't install solar panels, ASHP nor air conditioning.

I also don't have the storage space/capacity to put any more water tanks in. The existing 150l cylinder just heats up hot water for shower/kitchen/bath taps - it is not connected to the radiator system at all. That's fine as it is and isn't the source of the eye watering bills - it's only when the heating kicks on in the winter that they begin to skyrocket.

 

[RandomGrinch]

Under the advice of my builder I replaced the gas combi boiler in my flat with an electric 9kw ferroli boiler + an immersion heater tank.

I'm afraid that was your first mistake

Even still, I'm finding the heating bills to be crazy in the winter, sometimes £15, £20, £25, £30 per day of electricity being used.

Any electric heating system (excluding heat pumps) will be virtually 100% efficient, no matter if the heat comes from a wet system, or wall mounted convector heaters.
The question then becomes - is the flat a comfortable temperature, or is it overly hot?
If you couldn't stand the flat being cooler, it would be unlikely that you would save money from any other electric heating source, unless you had off-peak charging of storage heaters etc.

Gas heating may be less efficient than electric, but it is still around 1/3 to a 1/4 of the cost per kWh.

If you want to save money and stick with electric, wrap up warm, have a blanket on the sofa, turn the thermostat/TRV's down, only heat the rooms you use and insulate the flat.

I may also question your cost per day for the heating - how are you keeping track?
At around 25p per kWh, your 9kW boiler would be running flat out for over 12 hours a day, at your upper figure.