FHB 157- adding a bathroom fan..in cold
I found the recent article on “adding a bathroom fan” (FHB 157) very timely as I have two bathrooms that I’d like to put fans in. However, I live in the prairies where temps. drop to -30C in the winter. Needless to say opening the window is not a practical ventilation option.
I assume this article does not address the issue of a cold climate installation. Would it not be prudent to install a ‘p’ trap config. to eliminate any cold air coming back down through the ductwork? Also, I saw no mention of using insulated ductwork to prevent condensation problems with the cold attic air.
Any thoughts or suggestions for installing a bathroom fan in a cold climate would be appreciated as I have never attempted this although I’ve read a couple articles.
Thanks in advance,
Mike
Replies
Do a search for exhaust fans or bathroom vent fans; it's a topic that gets a lot of attention on this site.
I live in CT along the shore and we have our cold days, though not nearly as cold as you, thank God. Vent fans are plentiful here, and yes, we insulate the duct to prevent condensation. Many years ago when I installed the fan in my bathroom, I was also concerned about cold air backdrafting into the bathroom (duct run of about 5 feet), so I bought several of those flappers (backdraft dampers) and put them in the duct from the fan. Although I haven't had a problem with backdrfating in that bathroom, there have been a number of fans I've installed using just the flapper built on the unit and a louvered exhaust grill out the gable end. Haven't had any problems with those either.
So whether or not adding more flappers helps prevent backdrafting, I can't say. I'm not sure about your P-trap idea; it would create more friction in the airflow, maybe doing more harm than good. And you would need a drain for the condensate to go, which might just freeze up anyway.
There must be others in your neck of the country with vent fans, ask around and see how the builders are installing them.
Good luck.
Ditto on the backdraft dampers. I use them in the great state of Minnesota with every bath fan installed. rg
Most fans and wall or roof vents have flappers, so you'd be doubly protected. You can use the flexible, insulated duct used for HVAC systems.
I think the article you mention suggets pitching the duct slightly downward toward the vent. This will help condensate flow out, and warm air stay in.
I think any p-trap you might create would be a great place to grow primordial life.
Check out efi.org for Panasonic fans, insulated duct, tmers and vent caps.
Al Mollitor, Sharon MA