Can chimney breast be used for extractor fan?

abankerbutnotafatcat

Hi everyone,
we have gutted the kitchen of our Victorian house. Previously, it didn't have an extractor fan and we used the old-fashioned method of ventilation namely, we opened the lovely large window but obviously that has its drawbacks for several months of the year!!

Our plan was to install an extractor fan into the chimney breast, duct it up and out through the wall. Unfortunately, our kitchen fitter drilled a hole in the breast, (a LOT of cinders came out which he said had been plugged with some cloth) stuck his hand up, wiggled it about a bit and declared that there is a metal lintel across the chimney breast preventing him from ducting.

As there would be a lot of extractor work involved including a structural engineer in removing the chimney breast we are resigned to no extractor fan (we're going to put one of these in instead http://www.screwfix.com/p/xpelair-sl150ht-axial-kitchen-extractor-fan-with-humidistat-timer/22698)

But I just thought I'd see if anyone had come across this issue before???

http://www.flickr.com/photos/78523497@N08/7442422124/

mart.vader

Just a suggestion - Is it possible to get the duct to enter the chimney breast above the lintel? or is the lintel at ceiling height?

I have seen set-ups where the ducting runs horizontally, above the kitchen wall cabinets and then out through the wall. Is there any reason why the ducting can't go out through the wall, to the left of your window?

abankerbutnotafatcat

Thanks for your reply. The lintel is definitely below ceiling height, the kitchen fitter's arm was touching it and it was up no further than his elbow.

It was always the intention for the ducting to run horizontally from the chimney, across the top of the units and out of the wall to the left of the window. However, it needs to go up the chimney in the first place and that doesn't seem possible because of the lintel.

ryder72

It sounds like a pretty convoluted run with numerous twists and bends and unless you have a very high capacity extractor with 5 or 6 inch circular section ducting, its very likely not going to move much air.

As a thumb rule 3m flat channel has the same resistance as 5m circular for the same cross-section and every 90 degree bend takes a meter out of the ducting efficiency so consider carefully what you are doing here. You might ultimately be better off recirculating using a high quality extractor.

That vent fan will get you past Building Regulations is necessary but don't expect it to do much more than produce enough air movement to blow out a candle.

Mistral001

Is it possible to put the exractor fan on the wall where the air is to exit through to the outside (to left of window) and then have a duct going through the back to the cupboards (if kept below shelves, it will not really affect there storage capacity) and then go through the side of the chimney breast below this lintel. It would thus be pulling the air out instead of pushing it out. Since the ducting would be exactly the same there would be little if any reduction in efficiecncy. The duct opening at the cooker side of the breast could have a small grill (large pententage of opeings and not just a vent grill) or be hidden behind say a 6" high piece of feature wood/ stainless steel across the top of the alcove for the cooker

abankerbutnotafatcat

ryder72 wrote: »

It sounds like a pretty convoluted run with numerous twists and bends and unless you have a very high capacity extractor with 5 or 6 inch circular section ducting, its very likely not going to move much air.

As a thumb rule 3m flat channel has the same resistance as 5m circular for the same cross-section and every 90 degree bend takes a meter out of the ducting efficiency so consider carefully what you are doing here. You might ultimately be better off recirculating using a high quality extractor.

That vent fan will get you past Building Regulations is necessary but don't expect it to do much more than produce enough air movement to blow out a candle.

The proposed ducting(no longer possible since finding the lintel hence the request for ideas) only had one bend - straight up chimney breast and one right bend over units and out of wall.

I don't think there are any building regulation considerations. We had a Victorian kitchen with a large window but not extractor fan. I wanted to add an extractor fan and had my heart set on it and cried with frustration when I realised I couldn't and instead we're having a wall-mounted extractor fan as a compromise which will be better than the nothing we currently have (note it does have extraction of 245m3 p/h which whilst significantly less than the fan we hoped for is a reasonable effort). I don't think there was any need to poo poo it, especially when it doesn't look like there's an alternative.

muckybutt

Have you considered fitting an extractor fan into the window ?

Even if double glazed a glazing company can cut a hole in it, reseal it and then redo the vac / gas in it. Then you just need a window kit for the fan, saves a lot of hassle with ducting and will be more efficent in the long run...so to speak.

abankerbutnotafatcat

muckybutt wrote: »

Have you considered fitting an extractor fan into the window ?

Even if double glazed a glazing company can cut a hole in it, reseal it and then redo the vac / gas in it. Then you just need a window kit for the fan, saves a lot of hassle with ducting and will be more efficent in the long run...so to speak.

Thanks for the suggestion. Will it be any more efficient than the extractor fan I intend to fit to my wall? (link to it was in my OP)

muckybutt

Ahhh I missed that doh !

Window or wall makes no difference, wall will be the cheaper option though.