fan ducting is not connected (ed.)

[DIYAmelia]

Hello all,
Whilst gutting bathroom chipboard floor in favour of 18mm plywood that is partially over the utility.room below I have discovered the utility fan duct (50cm) ends near on open soil pipe that is 4 or 5m in length horizontally interfloor. It is not connected. There is a steady draft from outside along this pipe. Also at the wall end the Louvre (not gravity flaps) is not directly connected to this soil pipe.
The fan has been exhausting damp air from utility room into interfloor space for last 18years.
This is a Persimmon home BTW.
I have seen the 'snagging' fixes needed on the newer Persimmon homes (like major structural defects) so something like this is minor in comparison. I have found quite a few faults since moving in 7 years ago and been rectifying them.

Question is what I do now?
The soil pipe is 110mm diameter brown one. The uninsulated ducting is fabric with circular plastic rings to reinforce.
I have some larger diameter ducting.

I have seen adapters for sale but the current ducting hose is about 95mm diameter.

Also, are the fans easy to replace? I currently have access to top of fan so it would make sense to replace fan. Any recommendations? Are fans hard to fit? It is standard plasterboard ceiling.

Finally, there is the gap at the Louvre. I suspected a bodge job as the surface temperature thermometer detected a temperature difference of a few degrees on the plasterboard ceiling below what I now know is the soil pipe.

There is an inch gap behind the Louvre vent allowing cold air into the interfloor space and behind plasterboard, cavity etc.

A lot a people have commented that gravity flap vents are noisy. Louvre just let cold or hot air in. There is 'cowled outlet' see Toolstation 18869 that has s flap to stop wind rain ingress but it looks a bit unsightly in my opinion.

Any suggestions?

I plan to keep the soil pipe.. Is it worth putting 100mm ducting through it? Insulated ducting is pricey £50 for 10 or15m but if it helps keep house warmer or cooler depending on time of year.

 

[KenGMac]

DIYAmelia, good evening.

Suggest you consider,

Use the 110 drain, feed an Un-insulated vent duct the plastic coiled metal type through the 110 drain.

Connect the flexible vent duct to the fan and the terminal.

NOW ? wrap the 110 drain with [say] glass wool insulation, that will provide a good degree of Insulation? + cheap???

As for the terminal? there are various types, but remember the glass wool wrap will [to a certain extent] deaden sound transmission?

Your replacement vent? I am no expert in that field, but once the cover is removed a quick wiring re-fit to the new fan of choice is easy as to which type, sorry I cannot help there, but make sure that the overall size of the replacement fan is larger than the existing, easier when redecoration comes around.

 

[DIYAmelia]

DIYAmelia, good evening.

Suggest you consider,

Use the 110 drain, feed an Un-insulated vent duct the plastic coiled metal type through the 110 drain.

Connect the flexible vent duct to the fan and the terminal.

NOW ? wrap the 110 drain with [say] glass wool insulation, that will provide a good degree of Insulation? + cheap???

As for the terminal? there are various types, but remember the glass wool wrap will [to a certain extent] deaden sound transmission?

Your replacement vent? I am no expert in that field, but once the cover is removed a quick wiring re-fit to the new fan of choice is easy as to which type, sorry I cannot help there, but make sure that the overall size of the replacement fan is larger than the existing, easier when redecoration comes around.

Thanks Ken.
Airtec bubble wrap sheet coated in aluminium would be a good choice to wrap and tie wrap the soil pipe however most of the 5m length is in the interfloor space under another floor I am not ripping up (chipboard sheets). Lots of copper pipes near soil pipe and electrical cables.

I might just use insulated ducting through soil pipe and buy an adapter. The soil pipe is 110mm diameter and the current fan ducting is 100mm diameter.

Had a look with endoscope camera at understairs toilet fan duct and it looks like it is a similar bodge. Louvre vent well silicones to brickwork, other side there is the cavity visible.

Really bad job by Persimmon homes.

What is really funny is the quality check sticker under bath where installers fitted a squashed bath basin drain that leaks when it back flows if hair etc reduces flow. A £5 part...