What is going on with my extractors?

housebuyer143

I have two loft extractor fans which vent outside. I went into the attic and I've noticed that the ducting was full of water. I emptied it into a bucket and got quite a lot out and noticed is also leaking out where the fan is onto the chipboard, which is soaking.

I have no idea what's going on or why it's doing this. It's the same setup as in my old house and we never had this problem.

As you can see I've lay towels to absorb the water that is forming. I assume it's condensation but what can I do to prevent it?

I also noticed this weird patch on the chipboard which looks like it's damp and expanded. It's kind of springy to touch. I'm not sure what that's about?

FreeBear

The water will be condensation from the warm air being sucked up from inside the house. Insulating the ductwork with loads of loft insulation will help to reduce the condensation. The alternative is to install a condensation trap and have it drain to the outside being careful to make sure it doesn't freeze during the winter - I would go for the trap+drain. Replace the hoses with smooth bore ducting will improve airflow too.

housebuyer143

FreeBear said:

The water will be condensation from the warm air being sucked up from inside the house. Insulating the ductwork with loads of loft insulation will help to reduce the condensation. The alternative is to install a condensation trap and have it drain to the outside being careful to make sure it doesn't freeze during the winter - I would go for the trap+drain. Replace the hoses with smooth bore ducting will improve airflow too.

Thank you. One fan has insulated ducting both sides and the problem seems less pronounced but then we don't use that one as much.
We ran out of insulated ducting for the final stretch and cheaped out 🙄 
I am glad it's not a fan problem and just the weather doing what it does. I'll look into that option, or at least buy insulated ducting for the rest.

ashe

I've just been through this. 

You have two types of duct there and they're both just thin plastic or foil, unless it is the insulated type and it's just quite thin? 

you need insulated ducting which has the foil inner, a layer of loft style insulation, then a flip outer layer. This stops the water condensing in its way out 

your ducting is also held on with just duct tape. I'd use a screw on clamp to hold it tight in olace and tou can use some duct taping to make that air tight if you like 

make sure your ducting runs are as short as possible with no bends or loosely laid ducting

we can't do a condensation trap as no easy access to the outside / no soil stack in the loft 

We also draped some insulation around the fan, avoiding the cables, to help prevent water forming inside that. My fan was dry but my friends was drenched 

ashe

Also, where is your extractor venting to? Make sure it's fixed securely to a vent tile or a vent in your soffits / fascia's, and if there is an adapter for those then you will want some insulation on that too as they're usually plastic 

housebuyer143

ashe said:

I've just been through this. 

You have two types of duct there and they're both just thin plastic or foil, unless it is the insulated type and it's just quite thin? 

you need insulated ducting which has the foil inner, a layer of loft style insulation, then a flip outer layer. This stops the water condensing in its way out 

your ducting is also held on with just duct tape. I'd use a screw on clamp to hold it tight in olace and tou can use some duct taping to make that air tight if you like 

make sure your ducting runs are as short as possible with no bends or loosely laid ducting

we can't do a condensation trap as no easy access to the outside / no soil stack in the loft 

We also draped some insulation around the fan, avoiding the cables, to help prevent water forming inside that. My fan was dry but my friends was drenched 

Thank you. The silver stuff is insulation ducting with the foil inside, fibreglass inner and foil outside. Not sure how thick it is, but it's £60 for 10ms at Screwfix. It's the only one they sell. 

I'll buy some more of this and replace the plastic ducting and pull it tight. Not sure if we can do the condensate trap as not sure where I would drain that too. 

I'll buy some clips as well to hold it securely on. the run is longer in this house than my old one so that is the only difference I can see that might be the problem, although it was all plastic ducting in the old place 🤷‍♂️

housebuyer143

ashe said:

Also, where is your extractor venting to? Make sure it's fixed securely to a vent tile or a vent in your soffits / fascia's, and if there is an adapter for those then you will want some insulation on that too as they're usually plastic 

So add, would it be okay to cover these with insulation? They won't catch fire?

grumbler

What fire?

It's OK to cover. If the duct is horizontal, then ideally you want it to have a small slope towards the eaves. If it's possible, it's better to make it from about 100mm plastic pipe - and no insulation will be needed in this case, although some insulation will do no harm.

Don't cover the fan though.

ashe

grumbler said:

What fire?

It's OK to cover. If the duct is horizontal, then ideally you want it to have a small slope towards the eaves. If it's possible, it's better to make it from about 100mm plastic pipe - and no insulation will be needed in this case, although some insulation will do no harm.

Don't cover the fan though.

I think he means the fan. I havent covered the fan in insulation, but I have put some around it. The electrical panel is on the top,  so I have left that. 

Mutton_Geoff

Run the fan for much longer as well to dry out the condensation in the ducting.

I've used this firm for fans, ducting etc in the past. A great range of stuff. No connection, just a happy customer.

https://fans4less.co.uk/