Boiler flue <300mm from internal corner

[ACOperson]

Told a prospective customer the other day the bad news that he can't have his new boiler flue where he wants it as it is too close either to the opening window or the internal corner. He wants it somewhere in a 500mm strip of brickwork and it just ain't happening.

He apparently got on to CORGI tech who told him that there are some boilers which can have their flues closer than 300mm from internal corners. I only ever install Vaillants & Biasi's, which are 300mm and 450mm from internal corners respectively.

I'm going to check manufacturers websites etc now but I wondered if anyone knows of any off the top of their heads any which are less than 300mm.

Cheers

 

[gas4you]

Vaillants can be down to 25mm as stated here from their instructions.

Dimension F

This clearance may be reduced to 25 mm without
affecting the performance of the boiler. However, in
order to ensure that the condensate plume does not
affect adjacent surfaces a clearance of 300 mm is
preferred. For IE, recommendations are given in the
current edition of IS 813.

 

[ACOperson]

Cheers Dave, have never really considered putting one in so close to a corner before but this guys flat is a real nightmare layout. Its a 3rd floor, mid-1980's built affair with windows everywhere and a small overhanging eaves right above where the boiler will go.

The other problem this gives me is that there is a neighbouring window along the 'other' wall from the internal corner (45 degrees to the wall the boiler is on). Didn't bother measuring how far it was as I was sure we couldn't go so close to the corner in the first place.

Now that you've suggested a boiler that may be able to go in there, think I'll go back and remeasure, maybe also try and get my CORGI guy in before I start any work.

Thanks for ur help mate.

Paul

 

[giblets]

The other problem this gives me is that there is a neighbouring window along the 'other' wall from the internal corner (45 degrees to the wall the boiler is on). Didn't bother measuring how far it was as I was sure we couldn't go so close to the corner in the first place.

You have also got to make sure the plume won't affect the neighbouring window otherwise the neighbours may well have a valid case for complaint.

 

[Agile]

Biasi now have a plume diverter kit, actually two types. However I am not sure if they have changed the instructions for the distance from windows etc.

CORGI still think the inlet part is the terminal so the same terminal rules apply. The fact that the discharge point is 1-2 m away does not interest CORGI.

Tony

 

[ACOperson]

I don't think thats correct Tony. When I was with VHL we did loads (more than 2 per week) where the air intake did not meet the minimum distance from windows, doors etc; however the exhaust was far away enough. All of them were notified. . .

Personally in this case I'd rather not use the plume diverter option as getting a ladder to reach the 3rd floor is a pain in the backside.

The option I'm angling for him to go for is taking a concentric flue through theliving room wall and outside. This way it would be far enough from everything to meet regs. He doesn't want it though as it will look strange.

I'm going to try and get CORGI down later this week...

 

[Agile]

I don't think thats correct Tony. When I was with VHL we did loads (more than 2 per week) where the air intake did not meet the minimum distance from windows, doors etc; however the exhaust was far away enough. All of them were notified. . .

Just because they were notified does not mean that CORGI would consider them correct.

CORGI say that if the diverting part falls off or is pulled off then the inlet part is still the terminal and therefore its still the terminal even if the discharge point is taken further away by the plume diverter.

You make your installations as you choose but consider the implications of a disagreement with CORGI when there are no other practical alternatives. Customers are inclined not to want to pay if they are told by CORGI that the installation does not comply.

Tony

 

[ScottishGasMan]

Out of curiosity (as I dont fit boilers, Im Just a fixer)

What would corgi do if you fitted one that is NCS with the flue??

Surely sometimes there are flats or small terraced houses where htere just isnt a place you can fit a flue to the standards?

 

[simond]

Following a discussion with CORGI a month or two ago it would appear changes are underway to make the OUTLET of a plume diversion kit equipped horizontal flue the part that attracts siting regulations.

CORGI have advised us twice that their inspectors will not pull up an installation where the clearances could not have been met traditionally, and the plume diverter outlet meets normal BS siting criteria.

 

[ACOperson]

Tony, by that reasoning CORGI could condemn every single boiler they look at because 'if the flue elbow coming off the top of the boiler was pulled off it would be flueing into the room the boiler is sited in'.

The plume diverter kits have clips to secure them to the wall, and in this case it is 3 floor up so no-one will be anywhere near it to pull it.

Also, as I've already said I AM going to bring a CORGI inspector up to have a look before I agree to take on the job.

Regarding notification, I could name 5+ big blocks of flats in Wandsworth Borough and probably the same number in Harrow borough where CORGI have inspected AND approved installations which do NOT meet what you state are the requirements. They are all 1940's-1960's built places, at least 3 stories high with open balconies allowing access to the flats, and the original boiler flues were either OF running up an internal chimney, or BF terminating at low level onto the balcony. They have ended up having the new condensing boiler flues exiting at high level onto balcony, air intake right next to kitchen window or front door <300mm, with plume diverter kit running at high level across the balcony (boxed in) to get rid of the POC. I'm talking maybe 350+ boilers (usually Vaillants) and counting like this between the two boroughs, and now I think about it there are quite a few in Islington borough council estates too.

Theres no way that the large scale contractors like VHL, Seaflame and Kier who are putting these in are consistently breaking CORGI guidelines every time they do one of these jobs. Very often, other than putting the boilers in the living rooms at the other end of the flat there is no option other than to keep them in the kitchen and to divert the fumes in this way. The VHL surveyors run EVERYTHING by their CORGI contact before doing any slightly unusual jobs as the councils of course make them rectify any such basic installation mistakes for free.

 

[ChrisR]

At the moment it seems to be a bit of a mess, different manufacturers say different things and where there's no guideline to refer to, corgi inspectors can be fickle.
Worcester are (were) particularly "old fashioned" in their ruling.

Perhaps the Worcester-type standard flue end, where you can divert the plume sideways without extra parts, would be useful 3 floors up?

 

[chrishutt]

Isn't it time we pressed for a sensible rationalisation of the whole flueing issue? Why can't all boilers use standard generic flue components, in the same way as they use standard generic pipework connections? Concentric flues are pretty much standardised around the 60/100mm (or ?/125mm) dimensions, or 80mm twin ducts. Why have each manufacturer specifying and marketing their own flue systems with varying application rules? It just makes the whole thing overly complicated, confusing and expensive.

Of course the question is rhetorical. We know that supplying flue components is profitable, much more so than supplying the boiler itself since the extra cost of more complicated flueing arrangements is rarely considered when a boiler is chosen. The customer, having chosen the boiler itself largely on cost grounds, is then obliged to pay whatever inflated price the supplier thinks they can get away with for the flue.

There is however one example of a boiler manufacturer already doing as I suggest. Keston use standard generic 50mm mu-PVC waste pipework for both flue and air ducts. Leaving aside the failings of the boilers themselves, the system works fine. Complicated flue and air duct runs are easily achieved at modest cost. Flue/air duct components can be bought in bulk and stocked if such boilers are frequently installed. No reason why all boilers shouldn't be flue/air ducted on the same basis.

 

[Agile]

Thats really the situation already Chris as there are only two or three flue parts manufacturers.

Problem is that each manufacturer makes his own decisions as to what clearances to permit or not.

Paul, I was only outlining the different views between CORGi and Biasi over what constitutes the flue terminal. As we know CORGI gives different answers depending on who you ask and what day it is!

The sooner a new set of rules was drawn up for condensing flues the better. The current rules are based on non condensing boilers. Whats the point of putting a metal guard to protect a gutter above a flue terminal when the flue terminal itself is made of plastic and the POC being discharged does not exceed 60°C?

Tony

 

[just_thinking]

just goes to show CORGI have not kept up with the changes in flueing.