Vertical Flue terminal through flat roof

[gunnag]

I'm in the process of having an old combi boiler replaced with a new one in the same location. An installer has surveyed the site and mentioned that the vertical flue which currently exits through a flat roof fails gas safety rules since its terminal is not 30cm away from the house exterior wall.

The installer has suggested moving the flue terminal outwards to a more suitable position. Whilst this sounds sensible it does involve cutting a new hole in the flat roof and sealing the old hole which is obviously expensive.

Not knowing anything about gas safety law I would like to know if it is admissable to modify the existing flue arrangement by adding a 90 degree bend so that the terminal points away from the exterior wall and meets the 30cm rule?

I have seen some flues which exit combi boilers through an exterior wall, are then routed upwards vertically for a metre or two and then have a 90 degree terminal. I was wondering if such an arrangement is allowable through a flat roof as long as it meets all the other gas safety rules?

 

[muggles]

It's got to meet the boiler manufacturer's installation instructions, which override all other legislation. Thus the answer to your question is "it depends which boiler is being installed".

 

[Walfred]

Thanks for the reply, I was thinking about having an Ideal Logic Plus 30 combi boiler installed as the replacement.

I've sent an email to Ideal Boilers to see what they recommend.

 

[muggles]

@shambolic can probably give you a quicker response

 

[shambolic]

No it’s not allowed

 

[shambolic]

A vertical flue must finish vertical in the roof flue kit.
You can’t have a bend and finish the flue horizontally away from wall.
Thats just nuts

 

[gunnag]

Thanks guys, I had another quote today from a RGI installer who confirmed that the flue definetly needs to be 30cm away from the exterior wall. He came up with a solution involving two 45degree elbows in the flue inside the flat roof which will move the flue well away from the exterior wall and will comply with the regs.
His quote was good and included a roofer to make good the old hole and also a combi-mate to ensure the heat exchanger is kept clean, I already have a magnaclene filter fitted.