Fan,ducting & condensation problems

[Ted Foy]

Hello,i hope you are well.
About 6 months ago an electrician installed a vent axia silhouete 150xt (241m3/hr 20w 3mtr recommened ducting) into out small bathroom.

Instead of roofer puting roof vent directly above bathroom he put it at other side of building above kitchen were kitchen vent is (5.486mtrs ducting length). Vent axia only permits 3mtrs + theres also a 90 degree bend when ducting goes up to vent.

I dont know much about fans or ducting but when i have recently tried insulating our loft i needed to remove ducting to access area of loft.
When i removed ducting at roof vent there was a few bits of dripping condensation. I tried phoning electrician weeks ago but no answer.

I was thinking of replacing the axial fan with an inline fan + insulated soil pipe ducting +condensation trap as i read its more efficiant at pushing the hot air out of the vent.
Where im getting confused is the vent axia installed in bathroom (shower +bath+toilet. Installed on ceiling) is rated at 241m3/hr and when i look at inline fan were as the inline fan is rated at 220/280m3/hr which doesnt seem that much better.

Im also wondering how the hell i can set up a condensation trap as i only have an overflow pipe coming from loft cold water tank with no option to fit another pipe (inaccessable roof skeilings and high granite walls).

Last thing (thanks for sticking with me) is,am i capable of replacing the vent axia fan electrics with an inline fan myself. Im an ok diy'er.

I appreciate any help as flat is freezing (26 rolls of new insulation crammed into small livingroom for 3 weeks as cant put insulation until i fix this issue. Wife not happy).

Thanks for your time.
Teddy

 

[Wilko]

Hi Ted and Welcome to the Forum!
Sorry to hear about your condensation troubles. Despite the length of the run, are you getting enough ventilation from it? If so, maybe just change the white flexible ducting to an insulated one something like this
6 Inch x 10mts Acoustic Insulated Ducting - https://www.tlc-direct.co.uk/Products/FDAD6.html

 

[KEV 1 N]

When warm air meets cold air you get condensation....so warm air from bathroom entering ducting located in cold loft is causing condensation....insulated ducting is the answer!

 

[Rpa07]

I’ve learnt quickly that insulated ducting is the way to go BUT so much more expensive!

 

[Toneyz]

The ducting needs to be insulated ducting as above and as short as possible the longer the ducting the more resistance on the air movement I also from past experience found that using an axial fan on the ceiling other than a short piece of duct burns them out. You want to have the tile vent moved to where the fan is, use insulated duct and an inline centrifugal fan is a better choice.

 

[Marvo]

.........Where im getting confused is the vent axia installed in bathroom (shower +bath+toilet. Installed on ceiling) is rated at 241m3/hr and when i look at inline fan were as the inline fan is rated at 220/280m3/hr

The air volume figures you're quoting from the fans are the maximum they can move with no ducting or louvres attached.

To get a better idea of how the fan will preform you need to work out roughly what the static pressure of the system is then refer to the graph that all fans should have that tells you what volume it will move at that pressure.

You can have an axial fan and a centrifugal fan with the same volume in 'free air' but the centrifugal fan will far out-perform the axial fan at any given static pressure.

 

[Midwest]

Not to mention the noise the former will make in the middle of the night, when the commode is full.

 

[Ted Foy]

Hi Ted and Welcome to the Forum!
Sorry to hear about your condensation troubles. Despite the length of the run, are you getting enough ventilation from it? If so, maybe just change the white flexible ducting to an insulated one something like this
6 Inch x 10mts Acoustic Insulated Ducting - https://www.tlc-direct.co.uk/Products/FDAD6.html

View attachment 46223

Thanks for the reply. Yes,apart from the little bit of condensation the fan is good.
I noticed that the ducting is shoved inside of the vent,probs about 2 ft worth,and then duct tape. Was thinking if i correct the ducting and connection would probs be ok.

 

[Ted Foy]

The ducting needs to be insulated ducting as above and as short as possible the longer the ducting the more resistance on the air movement I also from past experience found that using an axial fan on the ceiling other than a short piece of duct burns them out. You want to have the tile vent moved to where the fan is, use insulated duct and an inline centrifugal fan is a better choice.

U have just gave me an idea. I have roofers working on roof. Might ask them how much much it would be. Cheers.