Help with exhaust fan wiring please


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Old 10-26-13, 05:30 PM
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Help with exhaust fan wiring please

I bought a Air King ESB130SH exhaust fan to replace my dying master bath fan. The old fan is a no frills fan, hooked to a regular 2-way wall switch, and has NO lights. The Air King is equipped with a humidistat, and the manual says it requires a 3-way switch, and should be connected this way (I'll skip neutral and ground).

swith-black<---->fan-black = Manual fan on/off circuit
switch-red<------>fan-red = humidistat-controlled circuit

However, since this is a retrofit, I do NOT have a 3-way switch.

However, I have a fan switch and a light switch in the bathroom. I want the current fan switch to control the manual fan on/off, and the current light switch to activate humidistat-controlled circuit PLUS light. So here's what I did in a junction box.

fan-wall-switch-black<---->fan-black = manual fan on/off
light-wall-switch-black<--->fan-red+light-black = on/off for light and fan-humidistat

However, BOTH switches turn the fan AND the light on, that is fan switch or light switch turn the fan and light on. I expect the fan wall switch to turn on fan only, no light (manual fan on/off), and the light wall switch to turn on light only, unless it the fan senses humidity at current setting (light on/off + fan humidistat).

Any clues? I'll try to post an actual wiring diagram. At least I don't see sparks
 
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Old 10-26-13, 06:18 PM
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Here's the wiring diagram.


If it's not shown, it's here Bath fan circuit | Flickr - Photo Sharing!
 
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Old 10-26-13, 06:43 PM
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hooked to a regular 2-way wall switch
What do you mean by 2-way wall switch. Do you mean a SPST switch? Does power come in at the fan or the switch. How many 2-conductor and how many 3-conductor cables at the wall. How many cables 2-conductor and 3-conductor at the fan?
 
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Old 10-26-13, 09:39 PM
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Here's the wiring diagram.
That's your diagram of what you did. The actual wiring diagrams are in the installation instructions. Did you follow those?

As a first try, you might try replacing one of your SPST switches with a 3-way switch and wiring it with incoming hot to common, the "manual on" feed wire to the traveler terminal that is energized when the switch is "on" (up) and the "automatic" feed wire that's energized when the switch is "off" (down). Make the connections at the fan as shown under Humidity Sensing Models, at the bottom left of page 3.
 
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Old 10-27-13, 12:32 AM
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Simplest explanation is that the humidity is high enough to close the humidity switch which puts both the fan and the light in parallel. You might try letting it run for a while with the window (if there is one) open and the door closed.
 
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Old 10-27-13, 04:38 PM
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Nashkat1, I currently do NOT have a 3-way switch, nor do I have the option of running a 3-cond wire from current switch location to exhaust fan location. so I can't follow the installation instructions verbatum, as I have noted in my orig. post. So even though I can replace the SPDT with a 3-way switch, I'll still need to run a 3-cond wire, and don't have that option.
 
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Old 10-27-13, 04:46 PM
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Ray2047, Yeah, I meant SPDT when I said 2-way wall switch. Power comes it at switch. All wires coming from wall are 2-cond wire. There is NO 3-cond wire going from wall to fan or to light, and I do NOT have the option to run it. New fan of course has the red/black/white/green wires internally.
 

Last edited by ZillaG; 10-27-13 at 05:08 PM.
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Old 10-27-13, 05:05 PM
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Furd, I thought about this, and you're probably correct. In my circuit diagram, this would make sense when I turn the light switch on, which turns on both fan and light. However, I can understand why, again in my circuit diagram, the fan switch ALSO turns on the light.
 
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Old 10-27-13, 06:20 PM
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The humidity switch will allow electricity to flow in either direction. If it is closed it puts the light and the fan motor in parallel so both fan and light operate when either the fan or the light switch is closed.
 
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Old 10-27-13, 09:39 PM
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Ray2047, sorry not SPDT, just SPST, or a simple toggle switch.
 
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Old 10-27-13, 09:42 PM
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Yes that makes sense, thank you.
 
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Old 10-27-13, 09:43 PM
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I currently do NOT have a 3-way switch, nor do I have the option of running a 3-cond wire from current switch location to exhaust fan location.
I understand that, but I don't see why you couldn't buy and install a 3-way switch with the two feeds for the fan and light connected to the two traveler terminals. The three neutrals in the switch box are already spliced together and could just stay the way they are.

It seems like doing thst would make operating the switch much more intuitive.
 
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Old 10-28-13, 07:20 AM
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Oh I get you now. Thanks, I'll look at this option.
 
 

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