Currently have Oil fired central heating using a standard boiler with cylinder (backed up by an immersion heater)

Mrs wants more space and is pursuing a new combi boiler to replace ours to remove the hot water cylinder to enlarge the bath room marginally!

What do i need to know (nothing atm!!) – efficiency/performance/cost/changes to the current system if any? Is there a secondary way to heat water should the oil run out in bad weather like last year?

anyone bored enough to advise me?

First up The oil didnt run out due to bad weather. It ran out due to bad planning.

Secondly , when i was looking it was advised that for oil combis only to look at worchester bosch or grant. Having had both in rentals on oil in previous houses i put my money on a grant – and stuck it outside at my back door….whichis great till you have a multi day power cut which lets the innards of the boiler get cold/freezy on the cold water side – the heating side has antifreeze in ( we had one this year ) …. How ever i want a generator for other purposes so as part of that it can run my boiler in the are powercut

How ever unless your boilers spackered beyond repair like mine was then i wouldnt bother replacing with a combi, maybe look at relocating the tank ?

Best advice is to get a few plumbers around to give you advice and prices.

We had our oil boiler replaced last year at over £3 grand and all plumbers advised that a combi wasn’t suitable. I cant remember why but it could have been the poor water pressure we have.

Perhaps seeing all the costs, she might decide the current bathroom size is OK 😉

The decision on combi or not should based on the number of hot water users. Obviously you will have a kitchen but if you have more than one bathroom\shower room I’d go for a system with a tank. It’s unlikely that a combi will be able to cope with the range of hot water demands that a house like that will require.

Only if its sized wrong.

My parents boiler was sized so to run 2 thermostatic mixer showers at the same time…. Does that no bother – rarely has to mind you

If thats a worry for you you put a leccy shower in one room

When was the last time you ran 2 baths at the same time ?

We’ve got an oil combi – a Potterton Statesman. It doesn’t cope that well with multiple HW use.

I’d prefer a tank to give a decent HW supply at peak demand times. I’d also go for a tank to give options for renewables, eg a duel coil for renewable HW, or an EMMA unit to give HW from supplementary electricity production if we ever install PV. Tank gives you the back up immersion too.

Isn’t simultaneous demand the main issue? I have a tank and a standard boiler, main issue we have is 3 boys emptying it so there’s nothing left for me .. a combi might be more appropriate for us.