Combi Boiler or not?


17 Aug 2006
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United Kingdom
I am getting quotes to replace the central heating in my house and so far these have all been for a combi boiler. My FIL was up at the weekend (he's a builder) and he reckons that unless space is a issue we should replace the old system with a new conventional boiler (i.e. keeping a tank). Space isn't really an issue as the tank is tucked away in an airing cupboard so is there any benefit to having a conventional sysyem rather than a combi? Broadly speaking which would be cheaper to install?
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For once I will agree with the Builder!

The combi will cost a lot more to instal.

The combi will give much reduced hot water flow to one tap at a time.

The combi may be more expensive than a heat only boiler.

Many thanks.

Is there any 'best' option between a conventional or system boiler? We currently have 1 bathroom but plan to add an en-suite in the future. The loft is already converted if that makes any difference.
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im facing the same problem, have just brought a house that although has a good central heating system I dont believe the water tank is going to be sufficeint to supply the two new en suites shower rooms and a further full bathroom....what do I do???
"system" boiler is one with built in expansion vessel etc ( did you mean combi?) water storage can be optimised by largest possible cylinder BUT quick recovery type ;) and also by storing water above 60deg. C and using blending valves on outlets ....also recommended to protect against Leigionella
Thanks for that.............not sure that I want to go for combi as I dont see the up side of one as the system and boiler doesnt need replacing so just the nw water cylinder would be good.....anything I need to consider when buying one (other than quick heat)...any idea of a ball park fiqure? or capacity size :D cheers
Blending valve lets you store water hotter than you really want it (up to 60) but supply it to the hot pipework cooler (say 47) so it "goes further".

Combi would provide pressurised HW which would be handy for your loft (no need for pump) but it wouldn't give enough HW overall.
Combis are much the same price as conventional boilers though, so if you're changing it anyway you could put a combi in to supply the loft, and also use it to heat the cylinder you have now - or a more efficient replacement.

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