Kitchen hob extract fan on an island hob
Discussion
Hello all
I'm looking for some advice on this. We have a kitchen hob which is mounted on an island in the middle of the kitchen. There is currently no extraction over the hob. From the hob to an external wall is about 3 metres.
I'd like to install an extraction hood over the hob, one that can be ducted to vent outside of the house (not a recirculating one). I'm planning to take up the wooden gloor in the room above (a bedroom we use as an office) and lay rectangular ducting in the gap between the joists.
I'd like the fan to be accessible for cleaning/repairs in the future, so it would need to be in the hood, or mounted on the outside wall...not hidden under the floorboards.
Has anyone done anything similar which will give me a few ideas of the challanges. The house is an old farmhouse with approx 1m thick stone walls.
Cheers
Tant
I'm looking for some advice on this. We have a kitchen hob which is mounted on an island in the middle of the kitchen. There is currently no extraction over the hob. From the hob to an external wall is about 3 metres.
I'd like to install an extraction hood over the hob, one that can be ducted to vent outside of the house (not a recirculating one). I'm planning to take up the wooden gloor in the room above (a bedroom we use as an office) and lay rectangular ducting in the gap between the joists.
I'd like the fan to be accessible for cleaning/repairs in the future, so it would need to be in the hood, or mounted on the outside wall...not hidden under the floorboards.
Has anyone done anything similar which will give me a few ideas of the challanges. The house is an old farmhouse with approx 1m thick stone walls.
Cheers
Tant
I’d second the above. We didn’t want an unsightly extractor above our island and went for a hob with a built in extractor. I was a bit of a doubter at first but it works really well.
I have megaduct (220x90mm) installed under the floor whereas you’d need it set for recirculated air with a filter box if you don’t want to dig the floor up.
I have megaduct (220x90mm) installed under the floor whereas you’d need it set for recirculated air with a filter box if you don’t want to dig the floor up.
Tant said:
Thanks gents...aye, that's a possibility. I get that they can filter out odour/grease and the like, but I just wonder where the water vapour goes to..
With enough velocity it goes outside before it condenses in the duct.Fan on ours is good enough for building regs to ventilate a kitchen. It’s in flat duct until the floor, then circular insulated alloy to the outside wall where I’ve installed a flap louvre. Needs to be 150mm diameter equivalent throughout. Filter goes in the dishwasher.
https://www.elica.com/GB-en/hobs/extractor/nikolat...
I've had a Bora down draft induction hob for a couple of years now. Was slightly sceptical about how effective it would be particularly as we couldn't vent it externally (UFH made that impossible).
Had absolutely no issues with condensation and just a month back I cleaned above all the kitchen units and there was no grease deposit just a bit of dust unlike with our previous overhead hood extractor which allowed a film of grease to settle on the top of units and always made cleaning a pain.
Had absolutely no issues with condensation and just a month back I cleaned above all the kitchen units and there was no grease deposit just a bit of dust unlike with our previous overhead hood extractor which allowed a film of grease to settle on the top of units and always made cleaning a pain.
We really wanted to avoid a recirculating filter so with no way to duct an extractor hob from below, we made a bit of a feature out of our Island extractor hood as we had to box in a beam between the original two rooms anyway so used that depth to box in a section mirroring the size of the island with downlights in it and also uplighting LED strip as well. We used a Luxair hood thats shallow enough to sit in that ~200mm void and ducted it out to an external wall with solid 6" ducting through the floor/ceiling void. It works really well, and you can access the Luxair innards from below if necessary
caiss4 said:
I've had a Bora down draft induction hob for a couple of years now. Was slightly sceptical about how effective it would be particularly as we couldn't vent it externally (UFH made that impossible).
Had absolutely no issues with condensation and just a month back I cleaned above all the kitchen units and there was no grease deposit just a bit of dust unlike with our previous overhead hood extractor which allowed a film of grease to settle on the top of units and always made cleaning a pain.
Thats reassuring, i've bought a bora and intend having it in recirc in the island for the same reasons. i've made some ducting to help direct the airflow to the floor level, and try and keep it away from the mdf stuff the units are made from.Had absolutely no issues with condensation and just a month back I cleaned above all the kitchen units and there was no grease deposit just a bit of dust unlike with our previous overhead hood extractor which allowed a film of grease to settle on the top of units and always made cleaning a pain.
Watching this thread as I have the same problem I'd like to tackle, particularly as well have no opening windows in the kitchen.
I was thinking rectangle ducting also but what happens if the joists above are running perpendicular to the direction you need to go.
Did consider downdraft extractors but then you lose the storage under the island?
I was thinking rectangle ducting also but what happens if the joists above are running perpendicular to the direction you need to go.
Did consider downdraft extractors but then you lose the storage under the island?
To my mind up through the ceiling is definitely the best approach.
As regards fan, why not buy a proper extraction hood? I have two of them.
Or fit an external fan that "pulls" air to the outdoors?
And even if you fit an inline fan under the upstairs floor how often do you think you'll need access? There's almost nothing to go wrong - it's just an electric motor.
As regards fan, why not buy a proper extraction hood? I have two of them.
Or fit an external fan that "pulls" air to the outdoors?
And even if you fit an inline fan under the upstairs floor how often do you think you'll need access? There's almost nothing to go wrong - it's just an electric motor.
Panamax said:
To my mind up through the ceiling is definitely the best approach.
As regards fan, why not buy a proper extraction hood? I have two of them.
Or fit an external fan that "pulls" air to the outdoors?
And even if you fit an inline fan under the upstairs floor how often do you think you'll need access? There's almost nothing to go wrong - it's just an electric motor.
I've had new ceilings fitted in our kitchen as part of the fit out, and as i mentioned above i'm putting in a recirc extractor hob, but i have buried in the ceiling a 250mm duct which is rigid, but has insulation wrapped around it. This is approximately above the island, to the left of the hob as I understand the extractor hobs work best when not competing with ceiling extractors. I'll likely fit a 2nd ceiling extractor above the dishwasher & sink area too. In any case, the motor will be a 500 cfm silent version connected to both (1 motor 2 vents) and will be housed approx 2m away from the ceiling vents, so its more accessible. Inline extractor motors do not need to be at the point of entry of the air, they can be near the exhaust, or anywhere in between.As regards fan, why not buy a proper extraction hood? I have two of them.
Or fit an external fan that "pulls" air to the outdoors?
And even if you fit an inline fan under the upstairs floor how often do you think you'll need access? There's almost nothing to go wrong - it's just an electric motor.
I'd not want the fan under the floor to be honest, your best off with a fan / motor built into the hood as you mentioned and no matter what happens, you'll want grease filters to offer the 'first line of defence', otherwise the fan/motor will become caked and best case, gunk up / burn out or worst case, create a fire risk.
Unless you end up with industrial grade filtration, with domestic gauze type filters, grease, oil and water will eventually line the ductwork over time and it's always advisable for you to be able to access/clean/replace the duct in future...ideally without digging up the floor. (whether this is by rodding or what have you).
If you going above the hob, go wider/deeper than the hob itself in order to 'catch' all rising odours and heat.
Unless you end up with industrial grade filtration, with domestic gauze type filters, grease, oil and water will eventually line the ductwork over time and it's always advisable for you to be able to access/clean/replace the duct in future...ideally without digging up the floor. (whether this is by rodding or what have you).
If you going above the hob, go wider/deeper than the hob itself in order to 'catch' all rising odours and heat.
Panamax said:
bmwmike said:
i'm putting in a recirc extractor hob
Why? It's a job half done. Most of them can be set up either to recirc or to vent out through a pipe. Have you bought something particularly limited? If so, stick it on ebay and get a proper one. Just my thoughts...MattyD803 said:
I'd not want the fan under the floor to be honest..
Snipped your message but same here, agree. I didn't want pipework under the floor either, same reasons - fat/grease etc, also the vent exhaust is at floor/rat level.LooneyTunes said:
We didn't want anything hanging down from ceiling so installed a downdraught extractor in ours.
Rises out of the worktop when in use, fan unit in cupboard below extracts via duct under floor.
Wouldn't want a combined hob/extractor unless they were very easy to clean.
We did the same. Works well.Rises out of the worktop when in use, fan unit in cupboard below extracts via duct under floor.
Wouldn't want a combined hob/extractor unless they were very easy to clean.
If you have an island in the middle of the kitchen and want to extract you’re going to need to run a ductwork system.
You can do this either by :
A. Removing the ceiling
B. Removing the floor
If you’re planning to do either of these anyway then no problem.
If not it seems like a big expense for a kitchen extract.
As I said earlier a recirculating extract is a more cost effective solution.
Put a separate through the wall fan elsewhere in the kitchen.
For the through the wall fan you can have a couple of set ups.
A. Intermittent extract - only running when switched on. You will need a 150mm fan running at 60 l/s (this will be noticeably noisy)
B. A DMEV system. This will run at a background rate 24/7. This rate can easily be calculated as 0.3 l/s per m2. (6 l/s for a 20 m2 kitchen). When you use the kitchen the fan can be boosted (possibly by the same switch you use for the recirculating extract) the minimum boost rate for this in the regs is 13 l/s. So considerably less noisy too.
Either of these approaches will be significantly cheaper than running ductwork.
You can do this either by :
A. Removing the ceiling
B. Removing the floor
If you’re planning to do either of these anyway then no problem.
If not it seems like a big expense for a kitchen extract.
As I said earlier a recirculating extract is a more cost effective solution.
Put a separate through the wall fan elsewhere in the kitchen.
For the through the wall fan you can have a couple of set ups.
A. Intermittent extract - only running when switched on. You will need a 150mm fan running at 60 l/s (this will be noticeably noisy)
B. A DMEV system. This will run at a background rate 24/7. This rate can easily be calculated as 0.3 l/s per m2. (6 l/s for a 20 m2 kitchen). When you use the kitchen the fan can be boosted (possibly by the same switch you use for the recirculating extract) the minimum boost rate for this in the regs is 13 l/s. So considerably less noisy too.
Either of these approaches will be significantly cheaper than running ductwork.
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