Boiler flue height

[Eve]

This is my first post so please forgive me if I've put this in the wrong section.

We are in the process of having an Okofen Pellematic boiler (that will provide our central heating and hot water) installed in our garage. The flue went up yesterday and I am concerned about the height of it. The flue is about a foot away from the apex of the roof. The closest buildings to it are approx. 5m away at one side and approx 7.5 - 8m away at the other side. The amount of flue protruding from the slope of the roof is about 2 feet but the top of the flue is just a bit higher than the ridge of the roof. From my very limited understanding of building regs part J (for where the flue should be positioned) I thought that the height of the top of the flue must be a minimum of 2 feet above the ridge.

I am not sure if there is a special reason that means that an Okofen boiler doesn't need as much height or if the installer just hasn't ordered enough flue to get high enough. I don't want to ask the installer about this before I get my facts straight as I don't want to seem like I know his job better than him, but I'm quite concerned about the flue possibly not having enough draw.

Can anyone there please give me a bit of guidance before I speak to the installer about this?

Thanks in advance.

 

[SimonJohns]

Refer to the manufacturers instructions for the boiler.

There are many factors to consider

Eg pitch of roof. Design of building. Type of appliance. Flue type

 

[kirkgas]

if it is a room sealed boiler it will come with a specific vertical roof kit which is desugned by the manufacturer and will basically stick through the roof to a predetermined height as there is a weather collar round the flue at a specific bit, so height is not adjustible, positioning on the roof is dependant or objects around it and the sizes you quote are way beyond causing any hassle,
if the appliance is open flued, then the flue termination needs to be either more than 600mm above the apex or no closer than 1500mm horizontally to the nearest point of the roof,
check the manufacturers instructions that the installer must leave with you there will be diagrams in there for the termination, should be easy to follow