Whole house fan, 2 fans 1 timer. Backfeed issue

[David Paul]

I’m installing a whole house fan and gable vent fan. I’d like both fans to turn on/off with the same Intermatic 12 hour timer. The WHF is a QuiteCool 2 speed that requires a constant 120v, with a spdt switch that supplies 120v to the low/high speed input. The gable fan is also a QuiteCool plug in fan. They are both powered from the same dedicated breaker. Both hot leads for the fans are currently tied together at the timer switch output(120v). From there the WHF lead goes to the speed switch and the gable fan lead direct to the fan. Currently with the timer off, when I plug in the gable fan the WHF turns on without the timer being on. I’m assuming the gable fan is backfeeding the WHF.
What is the solution to this? Can I use a relay to isolate the gable fan from the WHF on the same circuit? Thanks

 

[wyliesdiesels]

If the timer is off, how is the gable fan getting power? You connecting power behind the timer? If so, well of course the WHF will get power since you have them tied together at the timer.

Im not understanding the issue here. You want both fans to run with the timer. So theyre running as you have hem hooked up.

 

[BillK]

Sounds to me like you might have the neutral and hot reversed on the gable fan ? How about a quick diagram of how you have it wired ?? I am thinking it should be like this :

 

[dogdog]

could be hot and neutral is reversed at the whole house fan that was receiving constant power 120V ??? Don't even know why with this arrangement ...

"
I’m installing a whole house fan and gable vent fan. I’d like both fans to turn on/off with the same Intermatic 12 hour timer. The WHF is a QuiteCool 2 speed that requires a constant 120v, with a spdt switch that supplies 120v to the low/high speed input. "

yes pic or some crude schematic would have help.

 

[alfredeneuman]

The WHF is a QuiteCool 2 speed that requires a constant 120v,

According to wiring diagram it doesn't get a constant hot.
https://manuals.plus/quietcool/clas...eed_wiring_for_qc_cl-225031004700540060007000
Go to 8.2 the diagram for 2 speed. Replace the timer shown with your Intermatic.
It goes through the both the timer and the speed control before the fan.

 

[sparky 1971]

I'm as confused as anyone else here. If the 120 volt goes to the timer first, there should be nothing available to the house fan or the gable fan unless the timer is on. Are you sure the timer is wired properly?

The wire you're calling constant power is the neutral, the hot goes from the timer to the two speed switch and also to the gable fan. Then the switched legs will go from the speed controller to the house fan. The neutral will be tied together at all of the boxes without being attached to anything. It doesn't show that in the picture, it looks like it goes straight through, without going through the control boxes. You could do it that way by setting junction boxes, but it's easier to just take the cable through and wire nut the whites together at each box.

 

[David Paul]

Yea, I should have attached this:

 

[sparky 1971]

Yea, I should have attached this:

That may be the worst diagram I've ever seen. It makes absolutely no sense whatsoever. Look at the diagram in post #5. It will be just like that with an additional 14/2 going from the output side of the timer to the gable fan as well as the input for the two speed switch.

 

[David Paul]

This is how it’s wired. Note constant power to fan.



This is how the timer is wired…..Thank You BillK.

With the timer off, when I plug in the gable fan the WHF turns on.

 

[David Paul]

I would agree, but in that case what is done with the black wire coming from the fan motor itself?

That may be the worst diagram I've ever seen. It makes absolutely no sense whatsoever. Look at the diagram in post #5. It will be just like that with an additional 14/2 going from the output side of the timer to the gable fan as well as the input for the two speed switch.

 

[nadogail]

After reading this thread, my opinion is your electrician needs to take this project "back to the drawing board".

 

[alfredeneuman]

I would agree, but in that case what is done with the black wire coming from the fan motor itself?

Black is the high speed lead from the motor. Red is the low speed. White is the neutral.
Nothing else runs to the motor except for the ground

 

[David Paul]

To be alittle clearer if I can. From the fan motor itself comes 5 wires. Blue/red/white/black/green. Green and white we know ground/neutral. Blue high speed attached to speed switch. Red low speed attached to switch. Black is currently attached to constant hot.

 

[BillK]

Black is currently attached to constant hot.

When you say "constant hot" do you mean all of the time or when the timer is on ??? If it was all of the time the fan should always run whether the timer is on or not. Do you have a picture of the back of your timer and the 2 speed switch ?

 

[David Paul]

When you say "constant hot" do you mean all of the time or when the timer is on ??? If it was all of the time the fan should always run whether the timer is on or not. Do you have a picture of the back of your timer and the 2 speed switch ?

Yes, constant even with timer off. Fan does not turn on until power supplied from timer to speed switch. I’ll try and get pictures of switches

 

[dogdog]

I think that diagram is confusing as fak , op you should call the company and verify and confirm.

The diagram is a simplified diagram and your QC-xxxx model requires a constant 120V to feed on the black wire... that is why it is wired that way...

lets just walk through this... I think this is how it is working... and why you see the timer black wire and the incoming power is tied together. If it wasn't a USA company, I would have thought this is written and translated from the Chinese LMFAO... f-up to the max confusion... The only other time I seen a wiring diagram similar is those dam German track diagrams... or people that embrace those in the vw world...

Logically this is how this is working, it's the same as the diagram on figure step 6-11 with the exception that you have a constant 120V hot wire feed to that unit for what ever reason.

some basic facts first... you have a timer and a special 3 way switch (spdt center off) with center off I assume that came with the kit. ?

if you take the incoming power it feeds the unit requires constant 120V hot and neutral + ground... pretty clear on that part.

Then it requires you to tap that power and feed the timer... that is why you see the black wire from the timer feeding ... this is confusing if no one explained. the black wire on the timer is the input power... Neutral and ground is as is.

The red wire on the timer is output... which is not in the drawing probably just at the control switch area. It feeds the center tap of the three way switch center off (spdt center off)

from that switch it has two output... dependents on the switch position... so it if high it feeds to the blue wire, if low it powers to the red... It since house hold Romex only have black and white wire... it asked you to tape the white wire black... means only one of those wire is powered at a time.

Now take that guy that wrote the manual to the firing squad.

 

[BillK]

Exactly which model number fan do you have ?? The instructions posted by afn in post number 5 do not show a blue wire ??

 

[dogdog]

now to figure out how to wire in your "other" fan.

how do you want this to work?

you can tap at constant black wire and that other fan will always have power, you can provide your own control to it..

if you wanted it to work with the timer... you will probably have to run another set of wire from the controls... and see if you can tap the red wire output of the timer (that wire is not shown in your posted diagram). Just make sure the timer have enough amp to support both fans (loads).

 

[dogdog]

With the timer off, when I plug in the gable fan the WHF turns on.

can you define how you plugin in the gable fan ?

 

[David Paul]

dogdog, your explanation is spot on and the way I understand it. The WHF works just as expected. Timer on, fan on, speed as selected from switch. All good.

I am trying to control a gable fan to also turn on with the timer switch so both fans run at the same time. I have added 14/2 romex to an outlet. Hot to timer red output, white to neutral. All neutrals tied together. When I plug the gable fan into the outlet, the WHF turns on. Timer is off.

 

[David Paul]

BillK, fan model is QC ES 3100

 

[David Paul]

Gable fan just plugs in and works as expected when plugged into a different outlet

 

[dogdog]

I have added 14/2 romex to an outlet. Hot to timer red output, white to neutral. All neutrals tied together. When I plug the gable fan into the outlet, the WHF turns on. Timer is off

Without the gable fan plugin. Test the output of that red wire on the timer switch? is it outputting a 120V constantly or only when timer is on? and also make sure you verify you hot and neutral is properly connected that was mentioned. verify that only two wire and a ground is connected to the gable fan right? Black (hot) and white (neutral) and ground.

 

[David Paul]

Verified outlet wired properly. Timer only out putting 117v while turned on. If I turn on WHF/timer, outlet has 117 and gable fan works when plugged in.

 

[Sumboodie]

That may be the worst diagram I've ever seen. It makes absolutely no sense whatsoever. Look at the diagram in post #5. It will be just like that with an additional 14/2 going from the output side of the timer to the gable fan as well as the input for the two speed switch.

The way I interpret that diagram is the power, timer and switch are 3 ways to use the fan and you pick one of those. BUT maybe I'm wrong. Seems like a ton of wiring for a simple fan!

 

[dogdog]

Verified outlet wired properly. Timer only out putting 117v while turned on. If I turn on WHF/timer, outlet has 117 and gable fan works when plugged in.

if you verified that the wiring is correct and it is now not acting up... then there is only one more thing to check, is that your timer switch can handle the load of both fans at high speed. Normally those electric timer uses a "relay" to switch and have a limited AMP it can handle, long term wise, if the switch are overloaded it might have short live. you might have to call the company, or trying to figure it out if the spec is there. Good thing both fans are from the same company.

 

[BillK]

I hate to say it but that is the most confusing set of instructions I have ever seen. I have worked with electronics and electrical almost all of my life and I simply cannot figure out what they are trying to get you to do. I would really suggest you call the manufacturer and talk to them before something gets smoked or somebody gets hurt.

 

[David Paul]

I should have said if I plug in the fan after turning on the timer, it, the gable fan, works properly. The WHF still turns on with the timer off and the gable fan plugged in.

 

[David Paul]

First, thanks to all that took the time to respond to this thread. The videos the company provides seem to support the wiring diagram including the constant hot directly to the motor.

Good suggestion to call company. I will tomorrow.

 

[BillK]

One more comment and I am done I suppose it is possible that this is some type of crazy setup that does require the power all of the time to the fan and in that case it simply might not be possible to do what you are trying to do ?? If you leave the gable fan unplugged does the whole house fan work properly ?

 

[David Paul]

One more comment and I am done I suppose it is possible that this is some type of crazy setup that does require the power all of the time to the fan and in that case it simply might not be possible to do what you are trying to do ?? If you leave the gable fan unplugged does the whole house fan work properly ?

Yes

 

[infinkc]

What it seems is that the whf has constant power ran to it already, and used the low and high lines from the timer to trigger the fan on. Whf probably has some type of relay in it. I could see how the gable fan would trigger the whf in this setup.

Think your only option if you are trying to use the same timer is to wire in a relay off the timer to the gable fan.

 

[BillK]

Any luck with this ??

 

[fitter30]

This is how it’s wired. Note constant power to fan.



This is how the timer is wired…..Thank You BillK.

With the timer off, when I plug in the gable fan the WHF turns on.

Its two different neutrals back feeding

 

[alfredeneuman]

Its two different neutrals back feeding

Please explain further why you think this.

 

[David Paul]

Any luck with this ??

Well it is wired correctly with the constant hot lead according to manufacture. Proper operation as dogdog explained better then I could.

Curious about the 2 neutrals fitter30 refers to.

I am measuring about 2 volts at the timer switch output when the timer is off.

Again thanks to all who took the time to reply.

 

[BillK]

I just thought about something. Which Intermatic timer are you using ? How exactly is it wired into the system ?

 

[David Paul]

In my case the load is the speed selector switch. Model: Electronic Countdown Timer Switch LTB 12 Lighted.

 

[alfredeneuman]

Curious about the 2 neutrals fitter30 refers to.

There is no way the neutrals backfeed. They are grounded and just the return path for the motor.

 

[Zeke]

Looking forward to seeing how this is resolved. I don't see the same layout between the hand drawing and the schematic. They look different to me. Looks like the GF is powered by a control wire from the WHF.