Re-wiring interesting bath fan arrangement

[jives]

In a nutshell, have two side x side bathrooms (one is inside a bedroom the other not) that share a single exhaust fan located in the attic. The switch for the fan is not really a switch, but an automatic programmable timer that turns the fan on throughout the day to promote air exchanges. Problem is, it does not automatically come on when actually using the shower or toilet. The timer/switch is located outside one of the bathrooms. It can manually turn on the fan by pressing a button twice rapidly, and turn off the same way. Both bathrooms have a light in the ceiling exhaust opening. The light is switched in the bathroom.

I would like the fan to be turned on manually with a switch, with a switch located in each bathroom. Switch can be incorporated into the light switch, or separate. I don't mind keeping the single fan.

Thoughts on the best way to do this?

 

[Stuart in MN]

Two simple light switches installed in parallel with the timer should do the trick. When both are in the off position the timer will run the fan as usual, when either one is turned on it will force the fan to run as long as the switch is on.

 

[wyliesdiesels]

sounds like you want to get rid of the timer.

either you will have to run wire into each bathroom, or use wireless switches that activate a master switch in place of the existing timer where the existing wire feeding the fan is. not sure if there is a wireless switch product that is fan motor rated.

me personally I would just setup a 3-way switch circuit which means running **/3 NM between switch locations and **/2 nm-b from switch location without power (location that doesnt have timer) to fan. current **/2 nm going from timer to fan would be abandoned.

 

[75gmck25]

I think I'd just replace the timer with a standard switch, and then wire an occupancy sensor in each bathroom. If the switch is on and a room is occupied, the fan runs. Use a sensor that turns off after about 15-30 minutes of no activity in the room.

I think this general concept is often used for some recirculating hot water systems, so the water pump only runs when someone is using the fixtures.

 

[whateg01]

If it's one of the newer neutral-less timers, I don't think a parallel switch is going to work. Can a pair of three way switches be added?

 

[Bad Habit]

I have that exact set up too, sans lights (separate can lights). I just have all the switches in parallel. Bathrooms each have 60 minute push button timers, then there's a 24 hour timer stashed in a closet for the whole house ventilation. I don't remember if the push button timers required a neutral or not. A wall mount spring timer could work if a neutral wasn't available.

 

[dave*99]

This and the matching wireless 3way switch might work. The remote switch is battery powered and looks like a typical Decora switch. Surface mounted. No wires or holes.

 

[wyliesdiesels]

This and the matching wireless 3way switch might work. The remote switch is battery powered and looks like a typical Decora switch. Surface mounted. No wires or holes.

have to make sure its rated for the fan motor load

 

[dave*99]

have to make sure its rated for the fan motor load

• One switch does it all- supports loads up to 15A and 3/4 HP for control of lights, ceiling fans, exhaust fans, motors, pumps, and more

 

[jives]

Had not thought about a wireless switch. Nor have I checked the fan for amperage and hp, which I will do once the weather warms. The fan is in a walk up, uninsulated storage attic, but off behind a knee wall that has no floor.

My original thought was that a 3-ways switch would work, but groaned at the fishing of a 14/3 wire and installing new double switch boxes to replace the single switch boxes that control the overhead lights. In my garage I messed up on the 3-way controlling the overhead lights and had to re-do them, but I should have enough wire left over to do the garage. I do need to see the wire to the timer.

thanks, all.

 

[dave*99]

Had not thought about a wireless switch. Nor have I checked the fan for amperage and hp, which I will do once the weather warms. The fan is in a walk up, uninsulated storage attic, but off behind a knee wall that has no floor.

My original thought was that a 3-ways switch would work, but groaned at the fishing of a 14/3 wire and installing new double switch boxes to replace the single switch boxes that control the overhead lights. In my garage I messed up on the 3-way controlling the overhead lights and had to re-do them, but I should have enough wire left over to do the garage. I do need to see the wire to the timer.

thanks, all.

Should you need it, there is additional flexibility with the wireless switch.

This is a 2 gang box with 2 hardwired switches. It has a 3 gang cover and a wireless switch is at the end of the finger.