Concealed Gas flue in listed building

[JohnW2]

Technical Bulletin 008 (Edition 3): Flues in Voids - Registered Gas Engineer

Existing concealed room-sealed fanned-draught boiler chimney/flue systems in domestic premises

registeredgasengineer.co.uk

Interesting. Thanks.

It appears that this guidance (not law or mandatory regulation) only relates to "concealed room-sealed fan-draught boiler chimney/flue systems". Are open-flued boilers (like mine ) no longer available/'permitted'?

In relation to open-flued boilers (albeit perhaps on in relation to 'existing' ones, if new ones cannot be fitted), it says:

Boilers served by lined chimney/flues are normally open-flued and not of the room-sealed fan-draught type, so it is unlikely that the requirement for inspection hatches will apply. This is because open-flues can be checked in ways that a room-sealed boiler cannot e.g. visual, flue flow and spillage testing to verify they are safe and working satisfactorily.

... and perhaps of particular potential interest to the OP is:

However, there are some modern boilers e.g. those designed as replacements for traditional gas fire back boilers which are room-sealed and utilise the existing brick or block built chimney for the flue outlet pipe and often using the chimney as the air inlet route. These installations are normally designed so that the flue pipe is appropriately supported, continuous in length and that any joints in the chimney/flue system are exposed or accessible for examination.

It would therefore seem that there would be no 'inspectability' requirements with an open-flued system (if still permitted) if there were a continuous liner with no joints. Is that correct?

Kind Regards, John

 

[SUNRAY]

Interesting. Thanks.

...

... and perhaps of particular potential interest to the OP is:

It would therefore seem that there would be no 'inspectability' requirements with an open-flued system (if still permitted) if there were a continuous liner with no joints. Is that correct?

Kind Regards, John

That's the way I read that document.

 

[Ant1]

This may be of interest, a listed building where the exhaust flue for a new boiler was run up through the existing chimney.

Keston boilers fitted at Selly Manor Museum

Two 30kW system boilers have been installed as part of a refurbishment project

phpionline.co.uk

Thanks, this is interesting.

I also came across another useful article https://www.superwarm.co.uk/can-i-still-boiler-flue-chimney/, one of the other possible boilers to replace back boilers is the Greenstar FS 30CDi or FS 42CDi from Worcester. Viessmann seems to have one too, but cannot find the model number.

 

[Ant1]

Are open-flued boilers (like mine ) no longer available/'permitted'?

They are still permitted, mine is still working (touch wood) and get it serviced most years. I also had several gas safety certificates. It is just they do not make anymore, well it appears they only make a few and the literature around it is rare.

 

[JohnW2]

They are still permitted, mine is still working (touch wood) and get it serviced most years. I also had several gas safety certificates. It is just they do not make anymore, well it appears they only make a few and the literature around it is rare.

My quick look around has just found only the two Worcester-Bosch Greenstar ones you mentioned. Would they not be a viable option for you?

Kind Regards, John

 

[bernardgreen]

Technical Bulletin 008 (Edition 3): Flues in Voids​

registeredgasengineer.co.uk

Quoting from that Technical Bulletin

Scope of this Guidance
This guidance is provided for registered businesses/engineers and describes how to manage the risks arising from concealed chimney/flue system installations and how to satisfy the requirements of the GSIUR(1) in domestic premises.

For the purpose of this guidance, the term ‘concealed’ primarily encompasses situations where the chimney/ flue system passes through, for example:-

• ceiling voids
• floor voids
• or behind false walls, etc

But does not apply to chimney/flue systems incorporating:

• ‘vertical condensing flexible room-sealed fanned-draught chimney/flues systems’ installed in enclosures, such as constructional chimneys etc,. (see Note 3 and TB 139(4)), which are so sealed that any leakage of products of combustion cannot pass from the enclosure to any room or internal space;
• short chimney/flue systems e.g. which are connected directly from an appliance to outside air through an external wall (also see ‘Exception’ section).

Air inlet pipes of twin pipe chimney/flue systems are also excluded from this guidance.

 

[denso13]

It would therefore seem that there would be no 'inspectability' requirements with an open-flued system (if still permitted) if there were a continuous liner with no joints. Is that correct?

Yes, it was more of a comment that a boiler could be fitted with a balanced flue up the chimney. that couldn't be done, even with inspection hatches as the chimney passes through another property.

 

[denso13]

Interesting. Thanks.

Approved Document J, 1.47, comments on flues for all combustion installations. I know it isn't the law.

 

[denso13]

one of the other possible boilers to replace back boilers is the Greenstar FS 30CDi or FS 42CDi

They can't be run through a chimney in an adjacent flat.

 

[Ant1]

My quick look around has just found only the two Worcester-Bosch Greenstar ones you mentioned. Would they not be a viable option for you?

Not sure yet, it looks substantially bigger than the current one, hence the size of the enclosure might need increased. I would also need to install adequate drainage for the condensing pipe. I will know more at the next service when the back boiler is removed from the enclosure.

If interested the installation manual is available from https://www.worcester-bosch.co.uk/p...tanding-cdi-regular-installation-instructions

 

[Ant1]

They can't be run through a chimney in an adjacent flat.

I am a top floor flat, above me is a roof terrace with the chimney. Would it be suitable?

 

[boringoldcodger]

I am a top floor flat, above me is a roof terrace with the chimney. Would it be suitable?

I believe you'd be better off asking this on the Plumbing and Central Heating forum (regrettably you'd probably need to explain, again, how you got to this query).

 

[denso13]

Would it be suitable?

Possibly, still need access to the chimney in the loft which can be difficult in listed buildings.

 

[JohnW2]

Possibly, still need access to the chimney in the loft which can be difficult in listed buildings.

If all that is above the OP's flat is a 'roof terrace', there probably is not any 'loft', is there?

In any event, I thought we had agreed that the flue of the W-B Greenstar boilers didn't require 'access for inspection'. hadn't we?

Kind Regards, John

 

[denso13]

I thought we had agreed that the flue of the W-B Greenstar boilers didn't require 'access for inspection'. hadn't we?

I didn't. It is covered in the technical bulletin as a "concealed room-sealed fan-draught boiler chimney/flue systems"

If all that is above the OP's flat is a 'roof terrace', there probably is not any 'loft', is there?

Possibly, I mistakenly saw "loft" in there somewhere.