Anyone gone down the route of using their existing vertical chimney from a floor mounted boiler for a new condensing boiler.

Seems that it is possible but not common…

Mine is cited on an internal wall that puts it pretty much in the middle of the house so to cite a new boiler on an external wall will be a faff in terms of moving a load of pipes I suspect.

Yes, very straightforward swap, done a couple of months ago. Not quite as you asked though, it was a floor standing non combi with a vertical flue through a pitched slate roof, replaced with a wall mounted combi in same location. All the old flue was removed, but the new flue used the existing hole in the roof and made to line up with a pair of 45 degree joins between boiler and ceiling.

If I’m reading right, you want the boiler flue to go into an existing chimney? If that’s the case you may have limited choice. Worcester Bosch do an internal chimney flue system for their Greenstar 30 & 42 CDi floorstanding boilers but I’m not aware of any other solutions.

For what it’s worth, it will be much less hassle than you think for a new boiler to be installed on an external wall. I wouldn’t write that off as an option until you’ve priced up the WB solution above.

Flying ox that’s right – utilise the existing brick built chimney. So not possible to remove it (all two floors plus stack) and replace with vertical normal flue (well it would be but that would be a Lot more hassle than moving the boiler)

The set up seems to be pipes in the floor screed which whilst very neat and tidy doesn’t fill me with a warm feeling with regard to maintenance. I’ll get some quotes for the move. Cheers.

I had a boiler installed on an internal wall last year (ideal eco-something), the flue goes up into a void space in the kitchen roof, turns 90 deg and then horizontal for ~5m to an outside wall. had to put two small hatches in the void so the flue can be inspected along its full length.

The set up seems to be pipes in the floor screed which whilst very neat and tidy doesn’t fill me with a warm feeling with regard to maintenance.

You can always connect to the pipes elsewhere, just needs a stop end on the ones sticking out of the screed, although you do then have some dead legs which isn’t ideal.

TBH I’d at least look at the Worcester internal chimney thing. It’ll be more expensive than a standard boiler install but it’ll keep the current aesthetic and pipework.

Jambo – that sounds like it might be another option I did wonder what the run could be. There is already some boxing for the extractor gubbins I think.

Does the ‘horizontal’ need to slope back to the boiler?

Where did you put the condensate? There’s already a floor drain next to my boiler so wonder if I could use that – although it’s open so not sure if that causes an issue with potential combustion gases coming into the room

To reuse the existing chimney you would have to have a flexible flue liner (no joints) otherwise any joints have to have access for inspection. But if you use a flexible flue liner you would have to use an “open flue” rather than “balanced flue” boiler & then you run into difficulties with kitchen extraction. On that basis I’d investigate either a flue reroute or boiler relocation if I were you.

Thought this was going to be about your wife….. Disappointed.