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Island hob ventilation ducting

  • 03-06-2022 6:33pm
    Registered Users Posts: 850 ✭✭✭ seanand

    Hi all, looking to put a hob on the island and with vaulted ceilings were going to go with an integrated hob with built in ventilation, I have option now to duct it out before any floors go in but wondering where do you run the ducting. Getting underfloor heating so do I run it down under the insulation and across to the wall and up and then through the wall?

    It's impossible to find info for this online, I know I can go for recirculating if I need to but would rather not as it's not as effective. Thanks


  • Registered Users Posts: 37,814 ✭✭✭✭ Mellor

    Ideal you have a suspended or raised floor.

    How thick is you insulation and concrete slab? Are you planning on running it over or under slab?

  • Registered Users Posts: 850 ✭✭✭ seanand

    All that's in atm is foundation which is essentially at ground level so need to know soon before the subfloor goes in. I think we're putting in 100mm of insulation, I've 300mm in my head was the depth I needed to go down in the old part of the house but I'm not sure if that includes subfloor

  • Registered Users Posts: 30,748 ✭✭✭✭ Lumen

    I'm facing the same decision, although in my case the room has a suspended floor with a short run to the external wall.

    Ducted seems more effective than recirc, but how is it supposed to be cleaned? All that grease has to go somewhere. Is there some kind of grease trap arrangement or is there smooth bore ducting that can be rodded somehow?

    Friends have recirc and no issues, which in some respects seems simpler (apart from changing filters until the end of time).

  • Registered Users Posts: 8,013 ✭✭✭ Markcheese

    Well if all you can do is go down then that's what you'll need to do , it'll need to be a large duct , probably at least 120 mm,

    A smooth bore will make cleaning possible , and ideally the shortest distance possible to an outside wall , ( be aware of patio,out door areas) and obviously you'll need to come out about finished ground level outside . You may need to include a bigger vent box, or something on the outside wall ..

    this vent pipe is obviously going through the airtight layer of your new house - it'll need to be well sealed ..

    The extractors filtration system should take care of grease , but condensation could be an issue in the pipe , a slight slope to the outside on the pipe would help ..

    Slava ukraini 🇺🇦

  • Registered Users Posts: 850 ✭✭✭ seanand

    Ya been into a shop and going to go with 150mm pipe and going to go out just to the lift of the sink, it'll be the shortest distance.

    Been told everything will be caught by a grease trap or an overflow box so it should be just air, a slight slope upwards to the outside is what you mean ya?

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  • Registered Users Posts: 8,013 ✭✭✭ Markcheese

    Nope I meant slight downward slope towards the external wall - so that any water or condensation has somewhere to drain to ..

    The shop you're getting it from will probably have a better set of specs for how to fit ..

    Slava ukraini 🇺🇦

  • Registered Users Posts: 12,573 ✭✭✭✭ mfceiling

    What about a vented hob with recirculating extraction?

  • Registered Users Posts: 850 ✭✭✭ seanand

    Last resort, anyone I've talked to says vented is better

  • Registered Users Posts: 78 ✭✭ SodiumCooled

    I don't think it's seen as a last resort in general, it's pretty common nowadays especially with integrated ventilation. I may be wrong on this also but as far as I am aware recirculating extraction is the correct way to do it in a new build as an airtight house (which all new builds are) is not compatible with external vented extraction.

    Post edited by SodiumCooled on

  • Registered Users Posts: 1,625 ✭✭✭ muddle84

    If you have a MVHR system why blow all that hot air out and waste it? If you don't then fair enough, its still a hole in an airtight building(assuming its airtight!)

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  • Registered Users Posts: 2,971 ✭✭✭ standardg60