Flue compatibility - old boiler vs new condensing boiler

30 Aug 2011
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United Kingdom
Dear All

I am looking for a flat to buy here in London. The flat I looked at had an old Ideal Classic FF250 boiler installed in 1995 connected to an unvented hot water cylinder. They both look in bad shape and probably could use a refresh.

If I buy this flat I would like to replace with a newer condensing boiler, perhaps a combi.

I am concerned about the flue. Do you guys know if the typical flue used for the Classic FF250 could be used with a new condensing boiler?

It's a top floor flat and access to the flue is not easy.

I ask this because in my previous flat I had an even older boiler, a Potterton RS50, and the flue they used for that one couldn't be used for a condensing boiler (it was a metal flue), and I was told we would need scaffolding from outside and a brand new plastic lined flue, which was quite expensive.

So is this something we can fix from the inside, or would we need access to the flue from outside?


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No, you can't use the old flue.

you really need to find an RGI to give you a survey and price. Even if you haven't bought the flat yeyt, someone may be able to do an outside visual and give you an opinion on the practicalities of access. You may be charged for this service. I would probably charge a fee, to be refunded on doing the work.

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