We built a new full bath in the walk out basement. In order to tie in to existing sewer line, supply and vents, bath is in an interior space. We installed an efficient fan/light/heater unit, running a smooth 4″ duct in a ceiling bay for a 16′-run, then joined by means of a “Y” to exit the building at the terminus of the dryer vent. The dryer vent has its own, separate smooth duct run also 16′. There was just no room anywhere else to run the duct or make the exit to the building. This means there are two separate ducts, running parallel, until merging in a “Y” to pass through the blocking to the exterior of the building.
The problem is that when the dryer is on, the hot, humid air is flowing backwards into the “Y”, into the bath vent duct and out the bathroom fan! If we run the bathroom fan at the same time, it creates enough air pressure to solve the problem for the time being. But we need a better solution. Why is this happening? Background: elevation is approx 5,000′ and a colder climate.
Replies
Yes, you really shouldn't run the two into the same pipe.
What is stopping you from putting another 4" hole next to the dryer vent?
>>>But we need a better
>>>But we need a better solution.
I would say the better solution lies in finding a way to let the vents remain independent of each other. It's never a good idea to combine vent ducting.
Do you really want Uncle Hugo's stinky bathroom air being pumped back into your fresh laundry?
You're surprised??
If you absolutely, positively can't give it its own pipe (and you haven't explained why), install a damper on the bath leg. If that doesn't fix it, consider installing an inline fan after the Y, rigged to come on with the dryer. (There are fans made especially for dryer duty, and with a 16 foot run you could probably use the fan anyway.)