Domestic extractor fan problem/question

[Kate]

hey,

Hoping someone may know more on this than I do. Extractor fan above a shower in an en-suite, in-line fan so unit is up in the loft.
I know you can get condensation and "dripping" from the unit. How bad can this get?

Had a customer ask me to look at why their fan had stopped working. It was only 2 or 3 months old. Jumped up in the loft, removed the duct, could have easily filled up 2 buckets with the amount of water that came out. Travelled from the roof tile, right through the duct (had a drop point here) through the fan unit itself, into the duct on the other side. There was another drop point here which had stopped it from entering back into the shower room!

I may be completely wrong, and tell me if I am. But to me, that's far too much water for condensation surely? I was thinking faulty roof tile as this was existing and many many years old.

 

[Octopus]

Hum.... We had a small problem and I cured this by putting some loft insulation over the ducting....

IS that a "cheap" low powered fan? We have high pressure units if thats any help.

If the run is long could you raise the fan at all?

 

[Kate]

Standard 4" domestic. Meant to be 85m3/hr

 

[Octopus]

How long is the run to the vent?

 

[Kate]

Around 2 metres ish

 

[Andy78]

Those fans are weedy as you can get, you need something like a manrose mixed flow ...
An insulated duct can also help as Murdoch says, you can buy preinsulated double skin stuff.
also make sure there are no dips and wells where moisture can collect.

 

[Kate]

I can change it up in the loft to fix the issue, just trying to find out if could be condensation, or a faulty roof tile?
Just seemed a lot of condensation if it is?

 

[Deleted member 9648]

Had a lot of problems with condensation until a while back we changed installation practice. I remember one that filled half a bucket just months after being installed.
To prevent install the fan as close as possible to the internal ceiling vent, that prevents water in the duct being sucked into the fan. The long duct should be on the outlet side of the fan. Raise the fan up so that there is a fall on both ducts. Stretch flexi duct taught so that there are no sags to collect water, the weight of which will increase the sag and the water collection. Insulate exposed duct in the roof space.

Despite the above precautions I have still known water to collect and have now completely abandoned flexi duct in favour of solid for the main run but still adhering to the above principles. If you explain the problems with flexi to customers they are usually prepared to pay the small amount extra for a solid duct.

 

[Andy78]

These are what I use in lofts as standard. Great value for the performance and whisper quiet..

Manrose MF100T 4 Inch Inline Mixed Flow Extractor Fan with Timer - http://www.extractorfanworld.co.uk/manrose-mf100t-4-inch-inline-duct-fan-with-timer-247-p.asp

 

[Deleted member 9648]

I can change it up in the loft to fix the issue, just trying to find out if could be condensation, or a faulty roof tile?
Just seemed a lot of condensation if it is?

Condensation Kate....that duct snaking around like that will collect condensation at a very surprising rate.

 

[Octopus]

Around 2 metres ish

Not far then... they must like long steamy showers....

Had something similar a long time back, very long run to sofix vent..... so I placed the vent in a 3M length of gutter, raised the height of the fan .... and the problem never reappeared.

 

[Dave OCD]

Kate, in your picture there are two of the 'weedy' inline fans, had someone just left a previously failed unit there when it was replaced ?

 

[Kate]

Kate, in your picture there are two of the 'weedy' inline fans, had someone just left a previously failed unit there when it was replaced ?

Customer had bought a replacement before I arrived

 

[Kate]

These are what I use in lofts as standard. Great value for the performance and whisper quiet..

Manrose MF100T 4 Inch Inline Mixed Flow Extractor Fan with Timer - http://www.extractorfanworld.co.uk/manrose-mf100t-4-inch-inline-duct-fan-with-timer-247-p.asp

Original was a manrose one, have the details in the truck. Not sure which model but had some scathing reviews on amazon

 

[Octopus]

Customer had bought a replacement before I arrived

I would be warning them that it won't last very long!