Replacing boiler, but we have a Solar iBoost - go with combi?

blizeH

Hi,


We're replacing our boiler and everything seems to be pointing towards a combi boiler, especially looking at this list of pros and cons.


The problem is we have solar powered hot water at the moment, and in 5 years it's helped us save 1,898kWh in electricity... at our current energy rate with Bulb (12.443p) that's a potential saving of £236.16, or £47 a year.


As far as I can tell, a combi boiler (which doesn't need to heat the entire water tank) should save us more than that. Any thoughts please? Thank you

markin

Don't you mean its saved you 1,898kWh in Gas??? Or is the boiler not connected to the hot water tank?

blizeH

Oh, thank you! I'm dense and only just released that 1kWh of electric heating would equate to 1kWh of gas.

So at a price of 3.6015p per kWh I've actually only saved a total of £68.35... not even close to the amount we paid for the iSolar, eek!

That makes the decision to rip it out and go for a combi boiler much easier, thank you.

markin

Finding an old bill would be the best way to see the actual saving you made, With losses from the boiler and pipes it could be that Gas would use 3 or 4 KWH rather than 2 KWH for the iboost to heat the same amount of water.

Reed_Richards

I moved to a house (a bungalow) with a combi boiler and it's absolutely dreadful! The boiler is by the kitchen at one end of the house and the bathroom is at the opposite end. There used to be a hot water tank in the middle but that is long gone. The hot water from the boiler follows the same route it used to, first to the middle of the house and from there to the taps. This applies even to the kitchen tap which is very close to the boiler. You have to run-off a bucket full of water before the water from any tap runs hot, so expect an increase in your water bills if you are on a meter. And it you want to wash your hands with hot water you have to heat a full bucket load, which quickly goes cold standing in the pipes. So do make sure that either a combi is compatible with your existing pipework or that you can change the pipework as necessary.

EricMears

blizeH wrote: »

Oh, thank you! I'm dense and only just released that 1kWh of electric heating would equate to 1kWh of gas.

Allowing for the difference in efficiencies of gas boilers & electrical heating elements, 1kWh of electric heating is equivalent to several kWh of gas.

mmmmikey

EricMears wrote: »

Allowing for the difference in efficiencies of gas boilers & electrical heating elements, 1kWh of electric heating is equivalent to several kWh of gas.

...and not only that, you can buy 1kWh of electricity overnight for about 5p, store it in a battery and then use it to drive an ASHP whenever you want to deliver 2kWh or 3kWh heat, making it cheaper than gas on a cost per kWh of heat output basis as well. Doesn't scale too well at the moment because of battery costs and capacity but I'm doing just that at the moment and fairly confident it will cover my shoulder months heating needs.

silverwhistle

If I needed to replace my gas boiler I don't think I'd have a combi and no tank. Apart from testing I haven't used my boiler since March, I think it was, and not yet this new heating season either - currently shoving 1.6kW into the tank and already saved a kWh today. Having a boiler switching on and off all summer to get hot water doesn't seem an efficient way to do it, and like mmmmikey I'm thinking to the future of time of day tariffs.


When I go away on my skiing holiday I open the airing cupboard door and still get a small but useful contribution of heat to the core of the house.