relative boiler efficiency

[LindaLancaster]

We are trying to choose a combi boiler to replace a 20 yr old instant hot water boiler and a 25yr old CH boiler that 'lives' in the chimney breast behind a gas fire (Sorry! I don't know what they are called) Both boilers go out on a fairly regular basis and are probably using way more gas than we really need to be using. Also the water boiler is an eyesore, and so is the gas fire in front of the other one.

I've added up the total radiator output (some new, some will be replaced when we get round to it) and it will be 37,000 BTU. The thing is, 2 of these radiators will never be used except to air the rooms occasionally, and 2 more only get used once in a blue moon. 4 of the remaining 5 are always turned down low. In other words, we don't use our heating very much at all, but we do need the facility.

My question is, which would be more efficient - a smaller boiler running 'higher' or a larger boiler running lower? I've looked at the technical specs of Worcester boilers and can't decide whether a '24' or a '28' would be better for our needs.

DHW - we will be running a shower and a bath, plus hot water for the kitchen. I can't see that we would ever need the shower and the bath at the same time.

Hope you can help - you all seem very knowledgeable!

Love Linda

 

[PEDANTICVINDICTIVEMAN]

I should fit the 28Cdi, you will get better flow rate at the taps, the 24 and 28 are pretty much identical except for the DHW flow rate, and the 28 is not that much dearer, the boiler will modulate down to suit the heating load anyway as far as the heating is concerned.

You wern't married to Burt by any chance were you ?

 

[LindaLancaster]

Hi PVman

No, I was NOT married to Burt!!

Thanks for your reply. I think we will go for the 28.

Linda

 

[PEDANTICVINDICTIVEMAN]

Burt was on tv today, cassandra crossing.