Inline bathroom extractor fan vs normal ceiling fan

ando · 11-01-2024 9:52am #1

Hey can anyone explain the pros / cons on bathroom inline extractor fans vs normal ceiling fans? Are the inline fans better for longer duct runs? I have about four meters from the bathroom ensuite ceiling fan and the roof vent (vertical run) and I've had to replace three fans in the last few years as the fans must be struggling as eventually the hot air eventually condenses and ends up coming back down the ducting and destroying the fan's electrics...

listermint · 11-01-2024 10:00am

https://www.boards.ie/discussion/2058330787/inline-bathroom-extractor-fan-vs-normal-ceiling-fan

Biggest problem is moisture with these. Get a good strong airflow fan. I had a manrose inline did a solid job until I swapped out to centralised whole house mhrv.

If you don't have insulated flex pipe to and from your fan get some. But it'd also wrap that and the fan in rockwool. It needs protecting from the cold. The insulated flex hose on its own isn't superb tbh they're quite flimsy

ando · 11-01-2024 10:59am

Thanks, yes the ducting is fully insulated. I bought this one and it really helped.. for about two years but then a few weeks ago I noticed droplets coming through the fan and into the bathroom. The hot air is no longer fully being extracted, condensing and coming back down the ducting. I'm not sure whats happened or whats different but the condensation has got worse and the fan has finally now expired, so I'm looking again for another fan.

I seen the inline fans and wondered if they were better suited for a four meter vertical ducting run? Kinda similar to this picture? Or would I be better off just getting a more powerful ceiling fan? I dont know enough to know what is best suited

Flinty997 · 11-01-2024 11:08am

That looks like its close to an exterior wall. Is there a window or an exterior wall in the bathroom?

listermint · 11-01-2024 11:35am

I'd wrap that entire thing in rock wool and tape it. The plastic joints included. You've plenty of cold zones. I had the same flexi duct from screwfix the insulation is paltry. I got excessesive condensation too

10-10-20 · 11-01-2024 12:30pm

You're always going to get condensation in those things if they come off a shower, even insulated, and especially if they have any vertical rise at all.

If you can at all - a horizontal run between the joists and under the insulation and out to the soffit is always better, even if that means jumping a few joists and going back under the insulation again, it will remain warmer and less likely to condense and pool and then back-drip.

If you do have to do vertical then glasswool is easier to work with than rockwool, then a loose covering (tape or wrap) to give it some air-tightness and prevent any air infiltration. That's about the best you can do.

GPoint · 11-01-2024 12:36pm

Inline fans are often a lot more powerful and quieter than the ones built into ceiling. Less noise and vibration passed onto the plasterboard. Downside as said above is they fail if there is not adequate ventilation and moisture builds up in the ducts. I replaced a few fans cheap and expensive , average service time 1 to 2 years but I often leave them running all day to keep bathrooms dry.

Flinty997 · 11-01-2024 1:19pm

I wanted to go inline out to the soffit myself but couldn't find anyone to do it. Insulating the pipe is a new one on me. But makes sense.

I saw somewhere, open to correction that in Japan they sometimes have in-ceiling dehumidifiers to help with these issues.

10-10-20 · 11-01-2024 2:34pm

https://www.boards.ie/discussion/comment/121601576#Comment_121601576

I've been googling wall mounted dehumidifiers for ages now, very few if any from the well-known brands around Europe that I can see.

loyatemu · 11-01-2024 3:32pm

I thought out to a roof vent was preferable to the soffits due the risk of moist air making it's way back into the attic.

we've had a few drips coming out of our bathroom fan this last week (the duct is horizontal and under the insulation, but the vent is in the ceiling so there is a small vertical section) - it's just really cold, I think it's unavoidable.

listermint · 11-01-2024 4:03pm

https://www.boards.ie/discussion/comment/121602415#Comment_121602415

Definitely unavoidable. Can be minimised but the cold space attic and current weather is the defining battle.

11-01-2024 4:08pm

I good strong duct fan (the sort with two impellors one on either side of the motor are both quieter and much more powerful. The wall extractor fan never did anything near the performance of our loft installed fan.

ando · 11-01-2024 5:19pm

Thanks for the comments, I still dont know enough about the inline fans and I dont think its worth the extra cost if this is not really avoidable. I'll try buy a more powerful ceiling fan this time and put some extra insulation around the duct pipe. Never heard of glasswool, I might give that shot too. Its a horrible experience when you're standing under the extractor fan and water is dripping down at you!!

Flinty997 · 11-01-2024 5:21pm

I wonder would a moisture trap in the duct draining somewhere help. I also switched to smooth duct (wavin pipe) instead of a flexible pipe. Used to help. Not so much these days. Mine has long vertical section. Moronic design.

Currently I've resorted to using a portal dehumidifier on days the room gets heavy use. Trying it to help with drying clothes.