Plumbing in the Home/Bathroom Ventilation


Hello Jay,
I can't seem to find an expert who deals specifically with ventilation, so I hope that this question is within your subject knowledge.
I am in the UK and the regulations pertaining to ventilation may be different to the US.
My bathroom does not have a window and consequently an electric vent has been fitted to the ceiling.
This vent worked fine for 15 years until it became worn out and needed to be replaced. I discovered that it had been venting into the loft space, and I found out that this method is now frowned upon, as it should really be attached to a hose which will vent under the eaves.
Anyhow, I did the modifications myself, attaching a hose, BUT I have gone through three vent units in six months!
What appears to be happening is that moisture/condensation is forming in the hose itself and dripping down the hose into the electrical parts of the vent, which get rusty quickly and render the vent useless as it just stops working.
I just don't know the best way to stop this happening. Because the hose itself isn't that flexible, there will always be a bend in the hose where the moisture collects.
Of course, this never happened when venting into the loft space itself.
Your thoughts would be appreciated, as I can't keep going through vent units!

Hello Dave,
Here in the states I have seen bathroom vents installed in a variety of ways by builders who think that it's only air....what could go wrong...
Venting into attics, crawl spaces, and other none inhabited areas within the building is always frowned upon because of the excessive moisture and heat it introduces to the area. Here in Northeast US, it is imperative that the area above the building insulation be as close to the outside temperature as possible during the winter months. Hence, roof vents.  
Anyway, in your situation, if you want to continue to vent it as you are now after your modification, that exhaust piping MUST be heavily insulated. I do not recommend  the thin plastic flex hoses that most kits come with, I use 30ga galv. pipe and if possible cover it completely with fiberglass building insulation. In crawl spaces this works great. Not knowing your building I can only tell you that you may have to get a little creative with the insulation and wrap it the best you can with what will fit in the space. Remember, the thicker the better and try not to compress the insulation any more than you have to.
Lastly, You might want to consider a timer switch on the fan so you can let the fan run after showering  or bathing ,let the fan run another 10 or 15 minutes to get the moisture out and help the pipe stay warmer longer. With a time you can set it and not worry about forgetting to switch it off before leaving.
Hope this helps.

Plumbing in the Home

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Jay Nicholas


Plumbing & Heating (warm air, hot water & steam heat)


40 years in the business, 40 years as a lic. master plumber in NY State. Retired

Graduated Magna cum laude at the School of Hard Knocks

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Commercial, residential and light industrial. You name it ...I have probably worked on it

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