Bath Exhaust fan timer?

[Jerry Simon]

Doing new construction year-end warranty inspections for several houses in same subdivision.

One complaint was that the bath exhaust fan, in only one bath of three, never turned off.  Builder said this was normal.  You know what I said.

Just did another one in the subdivision, and one of the bath fans, different location from above, didn't turn off when its toggle-switch was turned off.  Homeowner said her handyman *adjusted* the fan, and now it still runs for at least a half-hour before turning off.

Any help understanding this would be appreciated.

[Tom Raymond]

They make run timers that keep fans on for a set countdown after turning off the switch. Could become of these. 

[Jim Katen]

Perhaps it's just an Oregon thing, but timers or humidistats have been required on bathroom exhaust fans for a least two code cycles. 

[John Kogel]

Believe it or not, the BC building Code requires the bath fan to run continuously in new construction. I think it has to do with off-gassing. Houses are built tight and locked up all the time. It is pretty standard practice to bypass the fan switch until after the code inspector has done his final inspection. 🤓 Sometimes the electrician or builder doesn't get back to installing the switch and the fan is found to be going strong a year or two later.

[Jim Katen]

Is there a provision for make-up air or is the fan just churning? 

[John Kogel]

Right, there needs to be an air vent, usually in a closet.

I built an addition to my 1984 house in 2016 and had to install both those things in the new part for final approval, no big deal, actually. Fresh air in the closet with a vent you can screw shut any time.

Edited August 26, 2020 by John Kogel

[ejager]

We've got a switch next to the thermostat that turns on both the bath exhaust fan and the furnace blower motor. The switch in the bathroom won't turn the fan off if this switch turns it on. There is a fresh air intake on the return air system ahead of the furnace.

I explain is as the switch you use when the heat and/or humidity levels necessitate an active changing of the air in the home - such as when you are having a house party. Most people seem to get it

Edited August 26, 2020 by ejager
Adding make up air info

[Jim Baird]

During my visit to Dublin, Ireland I stayed in lodging where the light and exhaust fan came on when you opened the door and stayed on after your exit.