Balanced flue up a chimney

[Fiendish]

We've just moved into an aged bungalow and the existing open-vented CH boiler (a floor standing Potterton Kingfisher) is on it's last legs. The existing CH boiler is flued into it's own chimney stack.

The replacement boiler will be a wall-mounted condensing boiler and it seems sensible to me to reuse the chimney for the new (concentric) flue. However, BG say that all joints in the new flue must be accessible and therefore the flue cannot be housed in the stack as access to the flue joints at a later date would be impossible.

I'm intending to get some alternative quotes apart from BG but I'd like to know if my suggestion is a possibility, so does anyone know if this is a requirement by law, or is this just BG being inflexible?

 

[baxpoti]

BG say that all joints in the new flue must be accessible and therefore the flue cannot be housed in the stack as access to the flue joints at a later date would be impossible.

GSIUR 1998 Regulation 27 (2) states

No person shall install a flue pipe so that it enters a brick or masonry chimney in such a way that the seal between the flue pipe and chimney cannot be inspected.

Case closed.

 

[Fiendish]

Hi, and thanks baxpoti

Possibly NOT case closed

I wasn't suggesting that the seal between the flue pipe and chimney could not be inspected, but the seals/joints between the different sections of the concentric flue pipe.

The flue pipe is made from 2 metre lengths butt-joined together, and it's these joints that would be enclosed within the stack and therefore inaccessible.

Perhaps in the eye of the regulations I'm splitting hairs, but to me there is a difference.

 

[kevplumb]

the seals/joints between the different sections of the concentric flue pipe.

how long is this vertical flue going to be

what boiler are you planning on fitting

 

[Fiendish]

Hi kevplumb & thanks for the interest

Boiler descision is not in stone yet, but it's possibly a Glow-worm 18Hxi.
There would be a couple of 45 degree angles to get the flue from the top of the boiler into the stack, but the estimated vertical flue length within the stack would be 3.5 metres maximum.

 

[baxpoti]

Point taken and agreed, this next reg is even more applicable.

Regulation 28 states;

'No person shall install a gas appliance except in such a manner that it is readily accessible for operation, inspection and maintenance'.

A room sealed flue is part of a gas appliance.

Case closed now?




How would the flue be supported?

 

[kevplumb]

i'd lend it a couple of quid

 

[Fiendish]

Hi again baxpoti

Ho, well, I guess that if 'A room sealed flue is part of a gas appliance' then it is indeed case closed m'lud.

Of course, if one could get longer lengths of concentric flue pipe then they wouldn't need joining and there would be no need for inspection access.

I hadn't given any thought to how the flue would be supported... was going to leave that up to the installer

 

[kevplumb]

point to note fella the MI's don't mention a vertical flue

 

[Agile]

The originally quoted regulation was meant to refer to a flue liner and its seal at the bottom of the chimney.

Where lengths of concentric flue are jointed then that joint has to be acessible for inspection and manupilation.

You could build access doors into the chimney breast at each 2m joint point!

However, have you worked out just how you are going to get 2m lengths of flue up your chimney?

Further point! You will need a vertical flue terminal. These are normally of the 125 mm size and the boiler manufacturer we do work for insists that the whole flue above the boiler is all in 125 mm when a vertical flue is used. Other manufacturers may have other requirements.

Tony

 

[Fiendish]

Hi Agile

have you worked out just how you are going to get 2m lengths of flue up your chimney?

'Down' the chimney!

You could build access doors into the chimney breast at each 2m joint point!

Now there's an idea but not one I'll be following up

Guess I'll just have to accept some ugly old white pipe sticking through the roof (no outside wall available). My, the management will be pleased...!

Thanks for your input guys

 

[Agile]

If a flue joint is not accessible then the installation of the boiler becomes Not to Current Standards and will not meet Building Regulations and will not be coverable on BG insurance cover.

I wonder what the CORGI installer will have to say!

Tony

 

[baxpoti]

Of course, if one could get longer lengths of concentric flue pipe then they wouldn't need joining and there would be no need for inspection access.

The flue also has to be fitted to the terminal approximately 300mm below the finish roof line. Inspection access?

 

[IJWS15]

I am not corgi and this may be a stupid question but can you still fit a conventionally flued boiler with a flexible flue liner inside an existing chimney?

 

[Agile]

I dont think there are any domestic conventionally flued boilers still available.

They will not meet the energy efficiency regulations!

The possible exception is if the dispensation for back boilers has not expired yet.

Tony