Extractor hood and Gas Boiler outlet regulations ?

[Rog]

I need some advice as to whether there are safety regulations or advisories around the siting of a (fan assist) gas boiler outlet in the near proximity of an extractor hood outlet ?

In planning a new kitchen I have one configuration where the hob/extractor would sit on the same wall as the wall mounted gas boiler which vents outside. The most viable route for the extractor hood would mean that the exit pipe would go through the same area of the external wall and so the two "exhaust" pipes would end up very close together - probably 6-9 inches apart.

With some re-routing of the extractor pipework I reckon I could possibly work around and below the boiler before exit so that the exhausts were maybe 18-20 inches apart.

Is this seen as being too close together such that exhaust gas/fumes from the boiler could be "sucked in" by the extractor - despite it being "in blow mode" ?

Any help or guidance will prove useful as I've asked several contactors for an opinion but not received anything definitive from them.

[John Stumbles]

The boiler manufacturer's instructions (which you should have, or be able to get from the mfr, possibly as a pdf on the web) will tell you how far away the boiler flue must be from any openings into the building. 150mm+ will probably be enough for a fan-assisted boiler flue.

[Mathew J. Newton]

As mentioned in the other response (so far) you'd be best checking with the manufacturer of your current/intended boiler.

For what it's worth, the installation manual for my Worcester-Bosch says the flue terminal must not be within:

- 300mm (horizontally) from another terminal, door, window or vent

- 300mm (below) an openable window or other opening e.g air brick

- 1500mm (vertically) from another terminal

I suppose the next question is does an extractor fan meet the definition of 'terminal', 'vent' or 'other opening'? I'd personally say yes to all three, or certainly the latter two! Thus at least 300mm clearance in all directions would be required.

Whether these are typical (regulated?) values I don't know but thought they may be of some use. BS5440:1 is mentioned in the above section however it doesn't detail the specific relevance.

I recognise it's the extractor fan you're locating however one assumes the boiler installation manual will contain the most strict/detailed requirements to be met.

Mathew