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-   -   Add Third Timer Switch to Central Exhaust Fan (http://www.diychatroom.com/f18/add-third-timer-switch-central-exhaust-fan-115865/)

MaxSteel 08-31-2011 04:16 PM

Add Third Timer Switch to Central Exhaust Fan
 
I have a "central exhaust" system in my house. The fan resides in the basement, and I have 2 timers in each of the main floor bathrooms. It also appears to connect to the humidistat on the wall upstairs.

I am trying to figure out what I need to do to get a third timer in the mix, for a new bathroom downstairs.

Does anyone/can anyone shed some light on this mystery?

I have searched high and low and I haven't found the concrete answer.

As much detail as possible is appreciated.

Thanks In Advance!



-- Central Exhaust Description -- :
Unlike older homes that have individual exhaust fans in each bathroom, each with integral ducting and vent hoods to the exterior, your home has only a single fan located in the basement. This larger-capacity fan is connected to registers in each bathroom, and normally at least one more in the main part of the home. These registers are connected to ducting that terminates in the fan housing. From there, a partially insulated duct vents exhausted air to a hood on the exterior wall of the house or foundation. The purpose of this central fan is to remove excessive moisture and stale air from the home. It can also increase the influx of fresh air from the exterior if a fresh-air intake duct is installed in the basement or connected to the ducting for the furnace.
The main reason this single fan has replaced multiple bathroom exhaust fans is for simplicity and to better control relative humidity (RH) in the home.

MaxSteel 09-01-2011 03:06 PM

If no one here has any answers, then perhaps does anyone know of another forum that might be able to assist me? maybe an electrician's forum? thanks again.

AllanJ 09-01-2011 05:26 PM

Each existing timer is like a switch. You could run a 12-2 Romex cable (14-2 for a 15 amp circuit) from one of the existing timers to the third location. Turning on the third timer will start the fan in the same way as turning on either of the two existing timers. The new black wire connects to the side of the existing timer where the fan feed is and remains, the white wire to the other side.

When two wire ends want to go under one screw, cut a short length of (here, black) wire and attach that to the screw. Wire nut the other end of the short length to the two ends in quesiton.

(Electronic, i.e. nonmechanical, timers are a little more complex to wire up; you may need to string additional wires so you have live power, the switched power feed to the fan, and a neutral all in one place. And run a 3 wire cable to the third location.)

If you happened to turn on two timers, the fan will run normally, stopping when both timers have timed out.

Central exhaust systems can be disadvantageous because they may favor one bathroom over another and will also lose considerable heated air during the winter.

MaxSteel 09-01-2011 06:57 PM

I purchased the house with the central exhaust installed, and to remove it now would be too much work. I suppose I could cut a new hole for the basement bathroom and have it on it's own fan system...I'll ponder that.

In the meantime, I will try what you suggested. I'll just temporarily add another mechanical timer on to one in the upstairs bathroom with nuts and short wires, and see if they both control the fan.

This is what I assumed, but when it comes to electricity I don't like to assume, I really..REALLY appreciate you replying.

After my test I will post my results so if anyone else is looking for this scenario, they'll have one solution.

Thanks again!





Quote:

Originally Posted by AllanJ (Post 719608)
Each existing timer is like a switch. You could run a 12-2 Romex cable (14-2 for a 15 amp circuit) from one of the existing timers to the third location. Turning on the third timer will start the fan in the same way as turning on either of the two existing timers. The new black wire connects to the side of the existing timer where the fan feed is and remains, the white wire to the other side.

When two wire ends want to go under one screw, cut a short length of (here, black) wire and attach that to the screw. Wire nut the other end of the short length to the two ends in quesiton.

(Electronic, i.e. nonmechanical, timers are a little more complex to wire up; you may need to string additional wires so you have live power, the switched power feed to the fan, and a neutral all in one place. And run a 3 wire cable to the third location.)

If you happened to turn on two timers, the fan will run normally, stopping when both timers have timed out.

Central exhaust systems can be disadvantageous because they may favor one bathroom over another and will also lose considerable heated air during the winter.


MaxSteel 11-01-2011 02:08 PM

Bang on, it worked like a charm. Sorry it took me a while to reply, but I had to figure out a way to get my 14-2 to the spot I needed it.

Thanks a bunch!


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