I have my boiler serviced annually by a big UK company,

In 2015 the engineer noted the flue was less than 300mm from the corner of the house. There is a high boundary wall between me and next door and the flue points out into my garden. It was classed as safe but I was advised it was not to current standards.

Same in 2016.

Now in 2017 it has been marked as unsafe.

I understand it isn’t to current standards. But does anyone know why it would be unsafe. No nearby windows and there is a high boundary wall. Flue direction is straight out towards my rear garden.

Not a gas or boiler man but when reading the isntallation manual for my boiler (worcester bosch condensing job) it had all sorts of different flue arrangements depending on where it exited the property. I know you weren’t supposed to have it firing over the boundary or near people’s faces. Only thing I can think is that there is a risk of weakening the corner of the wall if it’s within 300mm…..

Have you asked them why? Building control may have some advise online.

I can understand it being close to a window or even a door, but the corner of a building puzzles me!! It is also not pointing towards the neighbours garden,

NCS and unsafe are two different things. I would say phone gas-safe but they will be zero help (I have been through this regarding differing advice on a flue dilution system). What doesn’t help is that the relevant cert is the most recent one, and that the IGE regs are a closely guarded document.
Seemingly gas safe guys can report with impunity without a requirement to justify what they report and it is difficult/impossible for a client to get clarification on anything regarding regulations.
My understanding is that the regs updates aren’t retrospectively applicable unless the installation is changed, although it is commonplace for it to be portrayed somewhat differently.

I think the regs are 300 min clearance from internal or external corner.

Your boiler instructions overide the regs if they’ve got a different figure.

What make and model of boiler is it? Preferably with the GC number which would be in the format of XX-XXX-XX and I can look it up for you.

Thanks bear, I’ll have a look for the boiler number tomorrow. I’ve also fired off an email to gas safe as to why the regulations say that so I can understand.