Feasibility of re-routing back boiler flue to remove chimney

[andyscotland]

Hi,

First, I realise this would be a job for a registered gas fitter and a building warrant if I wanted to go ahead. Just looking for opinions on whether it's worthwhile at this point.

We have a Baxi back boiler, still with a few years of life left, with flue running up the chimney. It's one of the ones with a 1970s style gas fire on the front. I assume at this point there's a flue liner up the chimney as there appears to be a flue terminal on top of the stack outside.

The chimney render is cracking and bossed in places and the flashing has started to leak.

When the boiler eventually gets to end of life I want to replace it with a room-sealed condensing which will go elsewhere. Once the boiler's gone, we might want to remove the wall it / the chimney sits in to open up the kitchen and dining room. But we weren't planning to do any of that for perhaps another 3-4 years.

But I obviously don't really want to put much effort into stripping and re-rendering a chimney that I ultimately want to remove. We're also this spring/summer going to build a small utility room extension that will make it harder to get scaffolding to it in future.

I'm wondering whether instead is makes sense to demolish the chimney down to below the roof line, connect the flue in the attic to a standard flue terminal, then slate over the hole in the roof.

The new flue terminal would either need to have a metre or so of external vertical pipe to clear the nearby velux, or to be re-routed to come out of the roof / eaves somewhere else. It may become redundant when we replace the boiler because it's away from where we'd logically install a new one.

Anything I do is probably going to involve a bit of wasted work, so I'm just trying to figure out the best way to stop the water coming in while minimising that. And I'm not sure how big a job re-it is to re-route the current flue.

What do you think?

Cheers,
Andrew

 

[Madrab]

That's a significant piece of work, depending on what's currently on site and needs to be spot on. You really want a chimney specialist in that has experience with BB's and their required standards, to give you a proper idea of what can be achieved. Anything advised on a forum would really only be guesswork TBH.

 

[andyscotland]

Thanks Rob, even that's helpful : I wasn't even really sure if we were talking "big job" or "little job" (for the flue bit, I've a sense of what'll be involved in the masonry / roof bit). I'm more used to water / ventilation where it'd be fairly straightforward to expose the pipe, cut into it and joint it to a new bit, sounds from your comment like this would be more involved.

Any tips on finding a chimney specialist? A quick google is turning up sweeps, stove installers and general roofers - I assume what I need is more a Gas Safe engineer that's good on BB's. It's serviced by Scottish Gas, I take it there's no point phoning them / a general heating firm?

Thanks,
Andrew

 

[OwainDIYer]

I think it will be simpler, and this cheaper, to tidy up the existing chimney. If you don't want to re-render it can you strap some tarpaulin round it with builder's band and tuck ut under the slates for now?

 

[FiremanT]

You will be looking at several hundred quid for a RGI to install a proper flue alteration. And there are minimum distances to a Velux

 

[andyscotland]

Thanks both. FiremanT - several hundred quid wouldn't be the end of the world. Cost of stripping and re-rendering the chimney is probably at least that especially with access etc. And then would need access again (more complex next time) to demolish it in a few years time. I think we're OK for horizontal distance to the velux, so long as the terminal is above the top of it. If it was into the thousands it would obviously be more sensible just to do find a way to do the plumbing / new boiler now and take the chimney down once it's empty. But a few hundred to solve the problem now without bringing everything forward would be worth it for our disruption/budget/stress quota.

Owain, the chimney's visible from the street and the cracked render is a good bit up the stack (suspect water's getting in there and running down behind, rather than just needing to cover the flashings) so a tarp's a good suggestion for a temporary fix but the permanent fix is probably too far away for me to be happy with the look of it as a medium/longer-term solution. And if even I'm not keen I suspect my wife would have words to say on the subject

I've contacted a few local RGIs and a couple of roofers - will see if anyone bites.

 

[durhamplumber]

Its your money to waste as you wish.

 

[andyscotland]

durhamplumber... thanks... Reason I asked on here was I want to minimise how much I waste.

I've got to do something, so I've got 3 options. Replace the whole heating and hot water system now (potentially involving borrowing to do it sooner than we wanted so that'll waste the interest etc), leave the heating alone and get the chimney repaired only to demolish it in a couple of years time (including getting scaffolding to it twice), or demolish the chimney and re-route the flue.

What would you do if it was your money?

 

[Madrab]

If the baxi is working fine and running nice and clean then I would prioritise the work as far as finances are concerned.

If the chimney needs removed and a flue fitted for the boiler, then that would be Job 1. The main priority for me would be making the roof wind and water tight.

 

[andyscotland]

Thanks for that Rob.

 

[durhamplumber]

Back boiler v inefficient..wasting money keeping it

 

[durhamplumber]

Feasability...not the best idea you will ever dream up.I hope!

 

[andyscotland]

durhamplumber OK fair enough, thanks for the advice. Definitely agree the back boiler's inefficient which is why I want to replace it down the line and not with another back boiler as previous owners did, but configuration of the house and current plumbing makes that a decent sized job in its own right. Not least the logical place for the new boiler is in the extension we haven't built yet... Am speaking to a couple of local contractors so hopefully will find a decent solution.

 

[FiremanT]

Google plumber centre + 125mm Selkirk IL.
That should show the materials required to do a temp flue. You will need liner adapter , lengths, adjustable length, bends,terminal and a roof flashing. Plus, say, £2/300 ish labour.

 

[andyscotland]

FiremanT that's really helpful, thanks for the pointer.