Boiler Flue Size

[AndyDavis]

I've got a "standard" flue outside my flat, see pic. The boiler was put in more than 10 years ago, the canopy was put in about 4 years ago. I've now trying to change the boiler but I've been told by one installer that I need to have a long flue that extends beyond the canopy to prevent any build-up of flue gases.

Another installer started saying the same but then measured the distance between the current flue and the top of the canopy, came to over 3 feet. He said that was enough to fit a new flue as it is now.

The canopy was put in by the LA and they say that it's all perfectly fine as they've put in boilers since the canopy went up. There's 25 flats in my block and they all have the same "standard" flue, as does all the other similar blocks.

Who's right? What Health and Safety rules is the 1st installer talking about?

 

[dilalio]

The Mi's of the boiler you intend to buy will tell all!

 

[gasmanstu72]

yeah, find out from the boiler manufacturer what is allowed,
some might allow it others not,

have any of your neighbours had a new boiler recently? you can tell by looking at the flue if it's different to yours, maybe knock on their door and see what they got (or post a picture on here as most gas people will tell what it is) and then have a look online for the Mi's

 

[I Like Sleeping]

Jeez - cant be sure from pics but I suggest that you insist that the council/HA inspector comes down for a look

 

[Agile]

If a current condensing boiler is installed with a flue like those in the photo, it will cause annoying pluming ( visible white "steam" ) in cold damp weather.

Are some of the current ones condensing boilers ? Do they get complaints in the winter?

 

[DP]

Does not look right according to engineering judgement; MIs rule.
Can imagine on a calm cold day area under canopy having a good amount of POCs after other boilers kick in

 

[bernardgreen]

On a still air day ( no wind ) there could be a build up of combustion products ( fumes ) under the canopy which might enter an open window.

I consider the local authority is wrong to say that it's all perfectly fine.

as they've put in boilers since the canopy went up

is no proof it is acceptable to have a canopy installed over so many flue terminals.

 

[AndyDavis]

The current boiler (Vaillant Thermocompact 628) isn't condensing, but I'm hoping to install a condensing boiler like the Vaillant EcoTec Plus 624 Gas System Boiler. Am I better off fitting another non-condensing boiler, I thought all new boilers had to be condensing?

By the way what are MI's rules?

 

[DP]

Andy, a condensing or your existing boiler will produce products of combustion with elevated levels for carbodioxide (not saying it will kill you, but stick your heat under the canopy on a cold calm day with all those boilers contributing, you will likely be tad unsteady on your feet)

Anyone who makes any alterations that are likely to effect gas appliance operation, is required to follow Gas Safety (Installation and Use) Regulations. If you need further guidance, contact Gas Safe

Fitting a condensing boiler will result in visible plume, present fumes from existing boiler are similar but not visible

 

[DP]

By the way what are MI's rules?

Look at the boiler manual re siting go boiler flue

 

[dilalio]

To expand on the above...

MI's = Manufacturer's Instructions
I.e: the installation manual for a gas appliance has the 'de facto' rules pertaining to installation and flue arrangement.

However, with so many terminals in your location, this would be a "special circumstance" and I would be consulting the manufacturers directly for their advice. Following that, I would be approaching the local authority/management company/Landlords of the development to deal with the issues caused by the canopy, as far as boiler installation is concerned.

 

[simond]

I wouldn't put my name to any boiler fitted in that location.

My memory tells me that if the awning is open at both ends it might be considered acceptable; however, the standards and guidance assume one boiler, not many.

It is clear to me that on a non windy, cold day, the air inside the glass area will be vitiated by combustion products.

 

[AGAS]

IIRC regulations for passageways/ canopy only say combustion products don't cause a nuisance , don't cause obstruction and installed at certain heights from floor , but must not cause a nuisance ( depends what you / who calls it a nuisance ??????? ) . there is by-laws to be considered but i think in only some areas ????????, i think some boiler manu's only permit it to extend past canopy????? . but can see there maybe some problems with those windows in relation with other factors going on , i would get second opinion to whoever you choose to install your boiler . because all other flues have been done that way doesnt mean its correct . MI'S needs to be checked

 

[Razor900]

Looks to me like it's enclosed on three sides and half enclosed on the other.

I wouldn't fit one and I suspect that I might well AR it if I was on site.

 

[AndyDavis]

Thanks for all the great replies, I'll have a word with the makers and see what they think.

Is the law that you can't have flues below canopies or is it that the height between the flue and the top of the canopy has to be a minimum height? Are there any building regs that I could refer to?