Bathroom Extraction - Inline out of roof

[Participant]

I'm using 100mm insulated aluminium ducting from Amazon with a cheap backdraft shutter between the fan and the vent tile. It's a really good solid solution and all steam and moisture issues have gone. Also using Manrose MF100T.

 

[Richie]

I'm going to have a look at mine as I dont seem to have any condensation issues or water running back.

The fan is fitted to the ceiling of the bathroom and the duct (similar to downpipe but larger diameter) goes straight up to the roof and into a vent tile. Probably a 6-8 feet run? I havent noticed any water running back down and its all been ok for about 6 years

I'll try and remember to have a peek in the loft tonight.

 

[Participant]

I'm going to have a look at mine as I dont seem to have any condensation issues or water running back.

The fan is fitted to the ceiling of the bathroom and the duct (similar to downpipe but larger diameter) goes straight up to the roof and into a vent tile. Probably a 6-8 feet run? I havent noticed any water running back down and its all been ok for about 6 years

I'll try and remember to have a peek in the loft tonight.

If it's well insulated and the fan is powerful enough, I don't expect that there would be any issues with water or condensation at all.

 

[Richie]

If it's well insulated and the fan is powerful enough, I don't expect that there would be any issues with water or condensation at all.

Its not insulated at all. Not sure what model of fan it is.... I think its VentAxia but I will need to check tonight

 

[Richie]

If it's well insulated and the fan is powerful enough, I don't expect that there would be any issues with water or condensation at all.

Here's my setup I have... Vent in the ceiling of the bathroom and then the ducting going to a vent tile in the roof (looks like I need to dust the fan )

Not-insulated and the fan is at the bottom of the pipe (bathroom ceiling) but I have never noticed any water dripping back through the fan or anywhere

 

[Deleted User 298457]

What's your issue then Richie? :S

If it works and it's fine, it's fine???

 

[Richie]

What's your issue then Richie? :S

If it works and it's fine, it's fine???

Oh no issue. I just see lots of people seemingly having condensation problems or suggesting the fan should be as far along the pipe as possible, pipe needs lagged etc etc so, I guess I am more confused by them rather than looking for problems.

 

[Stu999]

Here's my setup I have... Vent in the ceiling of the bathroom and then the ducting going to a vent tile in the roof (looks like I need to dust the fan )

What’s that suspicious transparent bag?

 

[Richie]

What’s that suspicious transparent bag?

Hah, I only noticed that after taking the images so went back up and removed it as I noticed the tiny amount of condensation under it... Not actually ever been up inside my loft TBH. Looking to get it at least partially boarded at some point though.

 

[ChrisD.]

Oh no issue. I just see lots of people seemingly having condensation problems or suggesting the fan should be as far along the pipe as possible, pipe needs lagged etc etc so, I guess I am more confused by them rather than looking for problems.

I could be wrong but doesn't the condensation form on the outside of the ducting, which would soak into the insulation?

 

[img]

I could be wrong but doesn't the condensation form on the outside of the ducting, which would soak into the insulation?

with extractor its condensation inside where water in the air from your shower condenses in the cold pipe so doesn't make it outside and so the pipe is filled with water.

 

[LuckyBenski]

I could be wrong but doesn't the condensation form on the outside of the ducting, which would soak into the insulation?

Condensation will form on a cold surface in a warmer, or damp environment. Think of a glass of coke/beer/cold water in summer. Droplets form on the colder surface.

So in a shower extractor, the air inside the pipe is warm but the pipe surface is colder (if uninsulated in a loft).

 

[Richie]

I could be wrong but doesn't the condensation form on the outside of the ducting, which would soak into the insulation?

Warm air can hold more moisture than cold air. WHen the warm moist air from the shower is extracted into the pipe, the coldness of the loft causes this air INSIDE the pipe to cool quickly which then makes it dump the moisture it has absorbed but this happens to the air INSIDE the pipe making it run back down the pipe and into the bathroom again.

The air in the loft is already cold so, as long as you have sufficient airflow, there should really not be any condensation there (or very little) - as you can see in my own images, there is no condensation in the loft.