sandspider Posted November 9, 2014 Report Share Posted November 9, 2014 Hi all Bathroom extractor fan at my house didn't extract very well, so I installed a better one - something like this http://www.i-sells.co.uk/manrose-mf100t-mixflo-fan-100mm-inline-duct-fan-with-timer-two-speed-high-performance?gclid=CjwKEAiAvvyiBRDzrYuuldy6wB8SJABPJWObnsOnkzL-jXuwGtnfgvH40sKoFSU3PTJBJqFefSt_KRoCD-nw_wcB The fan does a good job normally, but recently it's started making some odd noises so I went up into the attic to have a look at it and there's water leaking out of the fan casing. The duct from the vent over the shower goes uphill to the fan, then the duct to the outside of the house goes uphill from the fan to the wall. So I'm guessing that condensation is running back down the tube to the wall and gathering in the fan body. It then gradually fills up until the fan blades start to hit the surface of the water, when it starts to make a noise and vibrate. So - solutions. I thought of mounting the fan up a foot or so higher, so less condensation will get into the fan body - mostly it will run down the tube to the shower vent or down the other tube to the wall vent. But I guess some will still gather in the fan body? And it might not move so much air if the ducts going into and out of it are at a bit of a restricted angle? Or, I could leave the fan at its current height, but mount it at an angle, so water will eventually flow out of the fan back down into the shower vent. But this is stil not ideal. Suppose I could drill another hole lower down in the external wall so the duct runs more level or downhill but this would be a ball ache as the wall is a good 18" thick. Any other thoughts on what I could do? Also, considering the design of the fan, it seems likely that some condensation will always gather in the fan body. Is this normal? Or might my fan be faulty as so much is gathering there? Cheers. Quote Link to comment Share on other sites More sharing options...
m3vert Posted November 9, 2014 Report Share Posted November 9, 2014 No idea about your problem but we have a couple of fans similar to this one and have no issue at all with condensation ;-) http://www.screwfix.com/p/manrose-shower-light-extractor-fan-kit-chrome-125mm/32488 Quote Link to comment Share on other sites More sharing options...
LondonLuke Posted November 9, 2014 Report Share Posted November 9, 2014 I don't want to state the obvious but I assume it's not small amounts of rain getting into the exterior vent? Quote Link to comment Share on other sites More sharing options...
sandspider Posted November 9, 2014 Author Report Share Posted November 9, 2014 No idea about your problem but we have a couple of fans similar to this one and have no issue at all with condensation ;-) http://www.screwfix.com/p/manrose-shower-light-extractor-fan-kit-chrome-125mm/32488 Thanks, but I don't want to change it again! It's only been in for a year or so. I don't want to state the obvious but I assume it's not small amounts of rain getting into the exterior vent? Pretty sure it's not - I put a new external vent on with gravity slats, so if there's anything getting in that way at all it's tiny amounts - and there are noticeable amounts of water gathering in the ducting between the fan and the shower grille too.. The attic is pretty cold, and the steam is obviously warm, so I assume there's more condensation at this time of year. Quote Link to comment Share on other sites More sharing options...
fenboy Posted November 9, 2014 Report Share Posted November 9, 2014 Sounds like you need to sort the fall out between the fan and outside , that of course may be easier said than done. Quote Link to comment Share on other sites More sharing options...
TIGHTCHOKE Posted November 9, 2014 Report Share Posted November 9, 2014 Which way is the outlet facing? Is it in to the facing prevailing wind which would delay the wet air moving out and allowing it to deposit the moisture within the tubing? Quote Link to comment Share on other sites More sharing options...
FalconFN Posted November 9, 2014 Report Share Posted November 9, 2014 Can you insulate the ducting to prevent such a large temperature change? Quote Link to comment Share on other sites More sharing options...
al4x Posted November 9, 2014 Report Share Posted November 9, 2014 We had the same make the pipe as short as possible make sure they are straight with no places water can build up and as above insulate the pipe well as the temperature difference is what is causing the problem Quote Link to comment Share on other sites More sharing options...
Fisherman Mike Posted November 9, 2014 Report Share Posted November 9, 2014 You need to install a condensation trap in all uninsulated fan ducts.. http://www.amazon.co.uk/100mm-Condensation-Trap/dp/B004ORG3VU Quote Link to comment Share on other sites More sharing options...
sandspider Posted November 10, 2014 Author Report Share Posted November 10, 2014 Many thanks for the suggestions. Prevailing wind is probably into the vent a bit, but there's not much I can do about that - it's the only wall I can get the extractor ducting to. The ducting was insulated (kind of!) between the shower and the fan, but not from the fan to the wall. So I'll give that a go, and install a condensation trap (didn't know such a thing existed!) too. If that doesn't work, I'll look at mounting the fan higher so the water can drain out. I assume that the overflow from the condensation trap has some sort of one way valve, so that the fan doesn't just suck air back up the overflow pipe rather than out of the shower? Cheers people. Quote Link to comment Share on other sites More sharing options...
SEshooter Posted November 10, 2014 Report Share Posted November 10, 2014 Can you insulate the ducting to prevent such a large temperature change?+1 warm moist air going through cold duct in loft = condensation Quote Link to comment Share on other sites More sharing options...
Fisherman Mike Posted November 10, 2014 Report Share Posted November 10, 2014 +1 warm moist air going through cold duct in loft = condensation Indeed...that's what the Condensation trap is designed for ...a length of small diameter pvc takes the condensate to drain similar to an overflow.. Obviously the original sparky/plumber/installer didn't put one in....bad, bad, person.. Should be something like this.. There's a lip on the inside of the trap to "trap" the condensation and stop it running back into the fan. Even with insulation you will get some amount of condensate forming. Quote Link to comment Share on other sites More sharing options...
sandspider Posted November 10, 2014 Author Report Share Posted November 10, 2014 Thanks Mike. Yeah, mine is nothing like that! It's all uphill and there isn't a vertical section to put a condensate trap into. Looks like one wouldn't work in a 45 degree ish angle of flexi hose stuff. Quite a lot of the stuff in my house was bodged, but at least I'm gradually making it better! Quote Link to comment Share on other sites More sharing options...
michufc Posted November 10, 2014 Report Share Posted November 10, 2014 I am a spark and install fans of this sort every install is slightly different but one thing you need to make sure is around the grill it is siliconed round so that eliminated sweater getting in from outside. Next as you have a up rated fan installed make sure when it's on that the grill flaps move allowing maximum air flow. Next with the install you have described I would be mourning your fan slightly higher than the exit hole as such but make sure it is in a straight line. Next is how close is the grill in the bathroom to the shower as if it is to close to the actual shower they have been known to draw water up from splashes. If the fan is making funny noises it is more than likely faulty and if it has had water in it dripping out then it will be faulty anyway. Again as said before you really want the run as short as possible. I have never had a major problem with condensation of this severity you describe and I have been doing this a long time. Hope this helps atb Quote Link to comment Share on other sites More sharing options...
Vince Green Posted November 10, 2014 Report Share Posted November 10, 2014 Wrap LOTS of insulation round the ducting, its basically a heat exchange/condensation problem. Water runs down so routing is important but set the fan to run for a good long time after the light goes off helps. The people who install these things are morons. Lots of hot steamy water vapour going up into the cold roof space, what do you expect? Would expect this thread in Jan not now Quote Link to comment Share on other sites More sharing options...
sandspider Posted November 11, 2014 Author Report Share Posted November 11, 2014 Cheers chaps, all taken on board. Quote Link to comment Share on other sites More sharing options...
Fisherman Mike Posted November 12, 2014 Report Share Posted November 12, 2014 Thanks Mike. Yeah, mine is nothing like that! It's all uphill and there isn't a vertical section to put a condensate trap into. Looks like one wouldn't work in a 45 degree ish angle of flexi hose stuff. Quite a lot of the stuff in my house was bodged, but at least I'm gradually making it better! The condensation trap normally fits just behind the fan and the ducting is then pushed into or over the trap. The outlet from the trap is horizontal. Quote Link to comment Share on other sites More sharing options...
Wilts#Dave Posted November 13, 2014 Report Share Posted November 13, 2014 Had this problem a while back on an install I did. Buy som insulated fan ducting, not the cheap white flexible stuff. That will help your problem no end as well as the obvious shortest possible pipe run etc. The temperature change is what causes such large amounts of condensation to form, especially if the duct in the bathroom is directly above a shower cubicle that has lots of use. Quote Link to comment Share on other sites More sharing options...
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