Kitchen Extraction Questions (inline in ceiling void?)

[Jambo-DIY]

I'm renovating an old house & so have access to the ceiling void to run duct from the fairly central cooker to the back wall (~5.60m) Why don't the joists run the other way!

I will run 150mm duct and am planning to fit a Manrose MF100 inline fan around half way along the run.

1. Is there a requirement to put some kind of fire proofing or access hatch for this fan in the ceiling/floor void? (I'll probably make an access hatch, easier now than later)
2. The fan has reducers that make it's openings 100mm, is it OK to install without these? The manual has no information about this, but surely constricting the duct diameter is not going to help flow.
3. The kitchen also contains a new Valliant Ecofit boiler, is it possible for this to have the flu gasses pulled back into the room? Any pointers for how to calculate the vacuum in the room to ensure it's safe?

Thanks for any help or advice offered!

 

[foxhole]

Fan is feeble. Would also be noisy and without grease filter a fire hazard , its intended for bathroom extraction.You need a proper kitchen extractor unit, boiler will be sealed from room and unaffected by fan.

 

[Jambo-DIY]

Thank you very much for the info.

So is it possible to get a hood with fan that will push air through a 6m long 150mm vent with a 90degree bend in it? Any advice for finding a hood that can do this?

 

[foxhole]

The price tends to dictate the quality when it comes to hoods, max recommended length is 5m for ducting, rigid is better than flexi but fan will still work, just efficiency will be reduced.

 

[Chud]

I agree with Foxhole - having been through this last year look for extraction rates and dB levels - we got this, it works very well and it's very quiet (on setting 1 we need to leave the extractor light on otherwise we forget it's on as you really struggle to hear it). I know it's probably no use to you as it's a wall mount unit but thought the dB and extraction figures might be useful.

I did reconnaissance at the local Wren showroom as most of their extractors are wired up so you can hear how loud they are, another pointer is the bigger the air intake area the quieter it's likely to be when shifting the same volume of air and the less strain you'll be putting on the fan which will help in shifting the air through your 5+m run of ducting.