Help Wiring Whole House fan with timer and 2 speed switch?

[Moparmaniac]

I'm getting ready to install a whole house fan in our home. While the instructions are fairly straight forward for wiring up the 2 speed switch that came with it, I'm wanting to add in a wall timer as well. The timer was made by the same company as the house fan.. It has 4 connections total on the back..on the back it has a picture of the wiring as 2 terminals on one side being Normally Closed and 2 terminals on one side being normally open.

Is lead and neutral coming in on one side (NC) and and lead and neutral going out on the other side (NO)? If that is the case I'm assuming the Neutral coming out of the timer runs back to the motor, while the Lead coming out goes over to the 2 speeed switch where it is wired to the lead wire then the black and red wires attach to the black and red wires at the motor.

Is a ground wire not involved in installing whole house fans? I'm not seeing mention of this anywhere in the instructions..I will recheck again to confirm this.

I have a home wiring book but they only show installing a house fan with the

2 speed switch and they have a separate section on timers but not combined so I was wanting clarification if someone will assist.

Thanks, Mike

[Moparmaniac]

Disregard this question..I misread the sentence about running the ground to a screw on the motor.

[gfretwell]

You want to connect the feed to the 2/speed switch through the NO contacts. That way when the timer is on the fan will run, either speed, selected by the switch..

[Moparmaniac]

I guess what I don't understand is the fact that other wall timers I looked at had only 2 terminals...I would think this is just the black or lead wire coming in and black wire going back out to the motor. Basically a simple disconnect like a light switch. The White wire (Neutral) would bypass the timer and wire straight up to the motor.

I'm not understanding why this timer I bought that is designed to be sold with this model of house fan has 4 on the back instead of the other timers that had two. Wouldn't just having the black feed coming in and black wire going out to the 2 speed switch work? What are the other 2 terminals for then? The white wire (neutral) that's what is throwing me off.

I would think the white would bypass this timer as well...but the other 2 terminals make me think that has to run through it too and that isn't making sense to me.

Thanks, Mike

[Terry]

The switch you bought is overkill. The other set of contacts are used to time (off) something.

I can't think of an example of why you would want to use this, but I am sure there are many.

[John Grabowski]

Don't connect your neutral to the timer. Run it straight through to the fan. The timer that you have will allow you to set the time for the fan to turn off or set the time for the fan to turn on. I am assuming that you want to use the timer to limit the hours that the fan will be on. In that case use the normally open contacts. This means that the contacts are open without the time being set, but will close and the fan will come on as soon as you turn the dial. You can use a volt ohm meter to verify this. Have the load from the timer go to the line on the speed switch.

[Moparmaniac]

Thank you! That was the answer I was looking for!

After I got home, I started working on the installation...to my surprise and appreciation...the house builders had preinstalled the electrical boxes and wiring for a timer and switch..all I had to do was connect them and go. Saved me a bundle of time!

Thanks again for the response.

Mike

[mm]

I couldn't think of any at first either.

One thing is that when the first set of contacts wears out, if ever, you can switch to the other set. :)

Or maybe, you could have a light sign that is on when the fan is off. The sign would say, "Fan is off".

Or there could be something else that someone wants on when the fan is off, or vice versa

OK, I can't think of one either.

[gfretwell]

You might want to have the fan on high speed during the day and low speed at night