Venting appliances through pitched roof

[chopkins13]

Hi all,

We're in the process of planning a single story side and rear extension that will have a hipped roof wrapping round the existing house. The extension is to house a kitchen/diner, utility and shower room.

I believe i will need vents for four reasons: Cooker hood, boiler, shower room extractor and finally the vented tumble dryer.

Due to the extension filling in the gap between our house and next doors, there is no external wall to the side, and clearly venting at the front of the house is very unattractive. The rear wall will be in the kitchen and, with the exception of the cooker hood, all other devices will be located in the middle of the side extension.

My question is, are there limits to the number of vent pipes we could have protruding from the pitched side extension tiled roof? And could any of the devices be combined, ie vented through the same roof pipe?

Thanks in advance,

Chris

 

[^woody^]

There are no rules for number of vents

You should not combine vents, unless the system is professionally designed

Consider using discrete profiled vent/terminal tiles which match the roof tiles.

 

[chopkins13]

Thanks for the quick reply woody, these forum's are really helpful!

I've googled the vent tiles you mentioned, my neighbour has one of these on their extension and I've wondered what it was, now I know!

Do you think these tile vents would be suitable for a vented tumble dryer or extractor hood? My only concern here would be either lint (in the case of the dryer) or grease (in the case of the hood) clogging up the tile vent, which on first glance appear to have some what more impeded air flow exists than say a straight vent pipe with rain cap set up?

Cheers,

Chris

 

[SimonH2]

There shouldn't be lint/grease going up the vent - there should be a filter first.

For a drier, you might consider getting a condensing one - my parents have one and turn it so it directs it's warm exhaust round the house. Beats pouring expensive warm air outside.

And don't forget that the boiler can only use a flue that's approved for that specific boiler. Personally I think it's a bit rip off - all the concentric flues are near enough the same, but each manufacturer has their own (expensive) options and you can't mix-n-match.

 

[^woody^]

You should not get any fluff or grease issues but layout of the duct is important

Some of the tile vents are designed to just vent the roof void, whereas others can act as a roof terminal for extract fans. Check this before deciding on one.

You then need to check the cooker extract fan instructions for the type of ducting and layout. You can't use the the thin plastic duct that you get for normal condensation fans - it should be aluminium or thicker pipe like underground drainage pipe. This then leads to possible issues with reverberation noise, so think about the layout and securing it - and insulating it.

There may be issues with long ducts, bends and condensation run-back for vertical sections

Basically, think about the duct layout, don't just run it anywhere

 

[chopkins13]

Thanks guys, some really helpful things to think about there. At least I now know it's not impossible to get everything vented properly. Time to do some research on boiler/flue choice and then sit down with the plans and work out layout of venting - simple and straight as possible will be the aim!

One final question if I may, if I'm venting the tumble dryer straight up, is it wise to put a bottle trap on the bottom of the vertical section, to catch any condensation that runs back? I've heard this suggested before?

Cheers

Chris