New extractor fan - ducting issue

RedXIV

Hey folks,

quick one hopefully. We moved into a new house a few months ago and the extractor fan is dead. Not a major issue, and we have a replacement bought but it looks like the ducting for the new fan is about 20% larger than the previous one. Also, the ducking goes from the extractor fan to a hole in the wall which is about a foot deep but looks like it was just drilled through.

2 questions I have then are:

1. How can I get the new ducting to fit to the hole? I'm guessing it should at least sit a little bit in the hole, but if I try and squeeze it in, the foil is tearing (I can trim this off as we have a lot spare). Should I be using something like this: https://www.screwfix.ie/p/manrose-round-central-reducer-white-125-100mm/10684 and fit the tighter end to the wall?
2. Should the hole to the outside be lined with anything while I'm doing this job?

Thanks folks!

Rustyman101

Yes I would use the reducer, obviously measure size according to outlet hole and outlet on the fan, you can buy all the hard pipe fittings in screwfix, 45,90 degree and straight pipe and connectors.

Makes life easy just installed an extractor last week using these parts.

You can buy an external grill if you are going through the facia

Personally I'd hard pipe as much as possible if not all the way.

10-10-20

https://www.boards.ie/discussion/2058337095/new-extractor-fan-ducting-issue

Can you see the cavity between the external leaf and the internal leaf of the wall or how do you mean drilled through? If so, it needs to be lined with a pipe.

RedXIV

As with most things, a picture is worth a thousand words so please find pics attached

Please note the annoying location of the power cable also

blackbox

You need to line that hole with a pipe or else the damp air will go into the cavity between the blocks.

RedXIV

https://www.boards.ie/discussion/comment/121796058#Comment_121796058

I was suspecting something like this, but full disclosure, I'm very much trying to rapidly ramp up on my DIY skillset here.

I'm guessing then I want my extractor fan ducting to be fed directly to the pipe that will line that hole? Will any plastic piping do the job?

10-10-20

What incarnation was that...? The hole was stitch-drilled into the wall under a socket and then not even lined with a pipe... bonkers stuff.

I'd be looking to do what blackbox says, any reasonable off-cut of waste-pipe should do, but the hole needs to be back-filled around the pipe both on the outer and inner leaf (hope you have access to the exterior). But as for that wire... I don't know what it's powering, but I'd be looking to shorten it to terminate below the vent, for sure.

RedXIV

https://www.boards.ie/discussion/comment/121796149#Comment_121796149

Ok great, that helps a lot (and validates my gut that something was off with this).

What would you fill the hole with? expanding foam or something? I do have access to the exterior so that's something.

The wire is the socket the extractor fan was plugged into when we moved in. In saying that, it hasn't worked since we moved in either.

10-10-20

Cement/mortar mix would be the normal method. But expanding foam should be fine on the inner leaf, but I'd do the external with mortar (for a permanent solution). The pipe should be running slightly downwards from inside to out.

10-10-20

Actually, thinking about it... if that's a noisy spot you might get a black-hole vent fitted into that to keep any noise down.

https://www.goodwins.ie/products/stadium-anti-draught-black-hole-ventilator-bm725-brown-outer-cowl-3461398.html

It's a whole unit, so no pipe required. Have a read of this:

https://www.boards.ie/discussion/2058291731/noise-from-external-air-vents