Locating extractor fan outlets

[overlander matt]

I need to put in an application for LBC for some bathroom extractor fan outlets. A couple of these outlets could go in either the wall or the roof. Is there a preference from a CO's perspective? The wall seems less work from an installation point of view. The outlets would generally be rear facing or tucked out of sight. We have to date removed 5 flues from gas appliances so I think overall we will have fewer outlets than we did when we bought the house...

We will have one new ensuite that will most likely need to vent through a slate roof. Alternatively there would be a long duct. Can anyone recommend a suitable product that I could use for venting through the roof? Some of the options are not too discrete....

Thank you in advance.

Matt

 

[Feltwell]

Can't help on the CO view but I did see these grilles the other day, and thought the 5" round one would look much better over a duct outlet than modern plastic grille:-

https://www.ebay.co.uk/itm/CAST-IRO...hash=item3afca32d6d:m:mrcO1ajPmRiZ3j-ImDBYdhQ

Use a black 4" round duct and I think that would look OK.

Slate roof vent - I think this is about as unobtrusive as you can hope for:-

https://www.roofingsuperstore.co.uk..._Od6GJQAF-JzIRHErL7f5gEITMk7a1psaAgCbEALw_wcB

 

[Abi Cott]

My CO specifically stated that extractor fan outlets were more likely to gain approval if they were close to downpipes and other extant structures rather than out in the middle of "virgin territory".


So downpipes, cables, vents, all grouped together rather than sprinkled across the rear face of the building.

 

[Owain]

You may also be able to drop down internally in rectangular ducting and out through a low level airbrick behind a bush.

 

[paulc]

I would also suggest rectangular ducting and avoid the flexible round stuff - The air will flow better inside a smooth duct compared to the lumps & bumps of a wire reinforced flexible hose. When I installed an extractor in the kitchen, rectangular ducting was used, and a 9"x3" vent fitted to a fascia board sitting just below a gutter. You'd be hard pushed to spot it.

 

[Zebra]

A warning though, little bathroom fans are not designed for long lengths of ducting. They just haven't got the power to push the air more than a couple of metres. Try to take it too far, and it just won't extract. There's nothing like installing it directly into the wall for effectiveness. Well, come to think of it, I have one installed in the wall, and opening the window actually clears the room of steam much faster. However, in terms of fans, the shorter more direct run is best.
If you do decide to duct upwards through an unheated space such as the loft, beware that the colder temperature will cause the steam to condense in the ducting, and possibly drip back down into the room. Very annoying.

 

[overlander matt]

Thank you for the responses. In terms of the outlets, I think the stick-on slate vent tile looks good as long as it can fit in place of a 10x16 slate. It will probably be positioned low on the roof so as not to be visible from below and to avoid any condensation running back into the room. Hopefully there is nothing controversial in its use from the CO's perspective.

I have already eliminated a few redundant flues (three on the front of the house even!!) but will aim for locations tucked out of sight and avoid holes in the older part of the house. Luckily the brickwork has had plenty of holes put in it so I should be capable of finding a few convenient locations. I like the look of the decorative vents Feltwell.

Thanks again.

Matt

 

[paulc]

I think the stick-on slate vent tile looks good as long as it can fit in place of a 10x16 slate. It will probably be positioned low on the roof so as not to be visible from below and to avoid any condensation running back into the room.

My concern with any vent mounted on the roof would be rain. On a roof, the vent would be exposed to water running down the tiles as well as rain. Without a cowl, there wouldn't be anything to stop water from getting in. Personally, I would favour a vent located in a sheltered spot such as under a gutter or eaves.

 

[Feltwell]

A warning though, little bathroom fans are not designed for long lengths of ducting. They just haven't got the power to push the air more than a couple of metres. Try to take it too far, and it just won't extract.

Have you any experience of the fans that go in-line in the ducting Zebra, are they any better?

I've heard the condensation thing before, I can see that would be a pain.

I've an idea for an extra en-suite here to one of the attic bedrooms, but for extraction the only 2 options would be a very short run to a roof exit, or a very long and twisty run to a wall mounted exit - so it has to be the roof really. I'd like a fan to be above the shower cubicle for maximum effectiveness.

I've already got some vent tiles in my roof (Building Control insisted when we re-roofed, despite using breathable membrane) - they can be connected to an extractor, and I know they don't leak at all. I can see the condensation thing being a pain unless I can drain the duct somehow. Best option looks like one of these traps fitted just above the ceiling, takes the condensation to a 20mm overflow pipe, I'm sure I could find an outlet for that.

https://www.amazon.co.uk/Blauberg-U...ocphy=9073570&hvtargid=pla-697442238227&psc=1

 

[Flyfisher]

I need to put in an application for LBC for some bathroom extractor fan outlets. A couple of these outlets could go in either the wall or the roof. Is there a preference from a CO's perspective? The wall seems less work from an installation point of view. The outlets would generally be rear facing or tucked out of sight. We have to date removed 5 flues from gas appliances so I think overall we will have fewer outlets than we did when we bought the house...

Did you apply for LBC when removing the 5 gas flues? Stictly speaking it's an alteration.

Of course, it's unlikely that the 5 gas flues were documented in the listing so they're unlikely to be noticed as missing. Likewise, the new outlets are equally unlikely to be noticed, especially if they are rear-facing and/or tucked out of sight. Am I the only one thinking that a formal LBC application is a little OTT in this case and that the CO is likely to have more important demands on his/her time?

 

[overlander matt]

I will let you know how we get on with the roof tile vent. The bathroom is located in the attic and I plan to site the fan on the ceiling close to the shower then run the ducting horizontally above the ceiling then follow the angled roof timbers down to the vent tile. Hopefully gravity will prevent any rain that is blown in from causing any problems. Until I see the tile it is a bit difficult to be sure this approach will work.

As for whether the CO really needs to get involved, I tend to agree this is trivial. As we have a few more significant changes in progress requiring LBC, we are adding the vents and other outlets to a second application that covers anything we missed in the first application... Interestingly, before we submitted the first application we had a pre-app meeting with the CO (who has subsequently moved on). We had asked for a roof light in one of the attic rooms overlooking the rear of the property. This was too controversial and so we did not bother to apply. The new CO tells me that he has nothing against roof lights so long as they sit flush with the slates/tiles and the roof timbers are left alone. This initially sounded like progress until we measured the spacing of the rafters - with a 400mm spacing this would ultimately only allow us to fit a roof light with a width of 200mm which hardly seems worth the bother. I can't even find any products available for such a small opening either. I wonder what can be so significant about one roof rafter? Elsewhere on the roof I have been replacing rotten rafters with new timber...

 

[Feltwell]

You'd be amazed at how extra light even a narrow roof light would let in, but I agree that stance is a bit daft. Usually 1 rafter has to be cut to fit one.

I thought this firm did made to measure, can't see anything but might be worth a call:-

https://www.therooflightcompany.co.uk/all-products/conservation/#attributes

 

[Zebra]

Have you any experience of the fans that go in-line in the ducting Zebra, are they any better?

I've heard the condensation thing before, I can see that would be a pain.

Yes probably better as they are more powerful but I'm afraid I can't remember any specific details.

One solution to solve the condensation issue is to install the ducting under the loft insulation or wrap it in rockwool.

 

[a twig]

Get the biggest in line centrifugal fan and the largest diameter duct that you can, and use as much solid duct and as little flexi as possible.

Lag the pipe to reduce condensation, condensate traps are available if it's still an issue.

 

[88v8]

I used one of these Vortice inline fans https://www.vortice.ltd.uk/shop/commercial-ventilation/lineo/lineo-100-t-v0/ with lagged solid ducting.
I made the exit between the joists, ie just below the roof.

Even with this socking great fan, it's still better to open the bathroom window. The thing is with extractors, well, it's like chimneys. For them to be effective in sucking air out, there has to be air coming in, and with the bathroom door shut, there isn't. So, for good extraction there needs to be a vent high in the door or somewhere else so the fan can suck air across the offending item - often the shower - without causing a draught.

Same goes for kitchen extractors, they have to suck air into the room, or they can't suck fumes out. In our kitchen I put an Xpelair, the type that one sees in pub windows, and it sucks air in through the window across the hob and straight out the fan.

Ivor

 

[overlander matt]

The slate tile has arrived and I can confirm it is just what is needed. In our case, we have a room in the roof space and the fan outlet through the roof slates will actually be lower than the inlet, avoiding problems with condensation and rain running back in. I can accept this won't be right in all cases but on this occasion, gravity is on our side.