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3-Function bathroom ventilation fan requires complicated wiring

3-Function bathroom ventilation fan requires complicated wiring

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  #1  
Old 01-27-14, 09:42 AM
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3-Function bathroom ventilation fan requires complicated wiring

1.) Originally, I had a single-function bathroom ventilation fan.

2.) I replaced it with a 2-function fan + light unit. I used a single switch to control both functions on the fan (light and fan) AND another light in the bathroom. This worked successfully no problems. The fan in this step had 4 wires coming out of it (WHITE, GROUND, LIGHT, FAN).

3.) Wife decided the step #2 fan was too noisy, so I got a new replacement model. This is a 3-function (FAN, LIGHT, NIGHTLIGHT). My plan was to wire up this unit the same way I wired up the fan in step #2, single switch controlling FAN and LIGHT and another light in the bathroom; ignore the night light and not have that function.

Sadly, I didn't study the wiring diagram for this beast until I had already mounted and remounted the fan a few times (it also has a lot of awkward mounting issues).

The fan has _SEVEN_ wires coming out of it:
1.) BLACK
2.) WHITE
3.) GROUND
4.) YELLOW (COMMON)
5.) FAN
6.) LIGHT
7.) NIGHTLIGHT

I currently only have a single switched 14-2 going to the fan. After studying the wiring diagram (see attached) and discussing with the HD employees, we decided that the fan wants to have an UNSWITCHED 14-2 (WHITE, BLACK, GROUND) going to it, AND another 4-wire bundle going between it and the 3-function switch (YELLOW=COMMON, FAN, LIGHT, NIGHTLIGHT).

I have several issues with that:
1.) I really don't want to run another wire between the switch and the fan.
2.) I don't want a 3-function switch, I want one switch controlling the fan and light function simultaneously.
3.) I need to have another light in the bathroom controlled by the same switch that controls the 2 fan functions.

The instruction manual gives no instructions for how to wire this other than using the 3-function switch. I tried a few combinations of wiring based on hypotheses about what the fan is doing internally and none of them were successful at getting the fan to spin:

1.) I split my incoming WHITE into FAN-WHITE, and YELLOW-COMMON; my incoming BLACK into FAN-BLACK and FAN-FAN.
2.) I split my incoming WHITE into FAN-WHITE and FAN-FAN; and my incoming BLACK into FAN-BLACK and FAN-COMMON.
3.) I connected my incoming BLACK into FAN-FAN; my incoming WHITE into FAN-COMMON; left FAN-WHITE an FAN-BLACK disconnected (wire-nutted closed).

None of these caused any behavior in the fan. Nor did they cause breakers to pop, or cause the other light in the bathroom to not function -- just no response.

I also tested several pairs of wires using a continuity / resistance tester, and the only pair of wires that showed continuity was FAN-WHITE and FAN-BLACK. Several other pairs which I had expected to show continuity did now, such as:

1.) FAN-FAN and FAN-COMMON
2.) FAN-COMMON and FAN-BLACK
3.) FAN-COMMON and FAN-WHITE

I'm loathe to give up on this fan as the specs on it (CFM and SONES) are just what I want, and the look of it is good -- and I'm willing to run a new 4-wire between the switch and the FAN if it's absolutely required. I really DON'T wait a new, funny 3-function switch in the bathroom -- I still think I should be able to jumper the 2 fan functions I want (LIGHT and FAN) together SOMEWHERE to be able to use only a single switch, and in that case I shouldn't have to run a new 4-wire from the switch to the fan, but a standard 14-2 should be sufficient.

Any ideas for how to get the behavior I want from this device? Despite all the mounting hassles involved I'm starting to feel like I need to rip it out of the attic and wire it into a cut-open extension cord and local switch just so I can make sure the wiring is going to function as designed before I go to the hassle of pulling cable, etc, etc.

Thanks!
 
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  #2  
Old 01-27-14, 09:52 AM
Tolyn Ironhand's Avatar
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What model of fan is this? I seam to recall wiring a fan similar to this at one time, is the motor or light low voltage?
 
  #3  
Old 01-27-14, 12:08 PM
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Here are the corrected images.

Name:  Wiring1.jpg
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Name:  WIring2.jpg
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  #4  
Old 01-27-14, 12:31 PM
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That looks like others I've seen that ran low voltage to the switch and back. That said, any switch or set of switches will work. The trick is getting enough conductors between the unit and the switch.

I would exchange this unit for one that doesn't require the fancy wiring. All bath exhaust fans should have their noise rating stated. Look for a low number for that.
 
  #5  
Old 01-27-14, 12:53 PM
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The wiring diagram does not make sense. Nor does it look like any fan/light/nightlight unit wiring I have ever done.
 
  #6  
Old 01-27-14, 01:59 PM
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I remember one posted here before that was similar and I don't think any one ever figured it out except that it needed some kind of proprietary switching and cable that wasn't included.
 
  #7  
Old 01-27-14, 02:26 PM
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The wiring diagram does not make sense.
The circuit is connected to the unit. The control power goes to the switch on the yellow and returns on the blue, red and brown. More than likely the switching is done with low voltage.

We've had one or two of these before, but it's been awhile.
 
  #8  
Old 01-27-14, 02:29 PM
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I remember one posted here before that was similar
ECHO, ECHO, Echo, echo, echo...
I don't think any one ever figured it out except that it needed some kind of proprietary switching and cable that wasn't included.
I thought we did, but I haven't found that thread.
 
  #9  
Old 01-29-14, 06:47 AM
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It's Model #VFB25ACLED1-5 from Hamptom Bay.

I was able to get the nightlight and light functionality to work last night by wire-nutting the yellow-common to either the light or night light, and wiring up the switched hot (black) coming off my normal switch to the fan's black input (where it wants unswitched hot). This seemed pretty obvious in retrospect, as what the switch does in the wiring diagram is complete the circuit between yellow and function (fan, light, nightlight). This technique that worked for light or nightlight did NOT work for the fan function -- so I'm suspicious that the FAN function might simply be defective in this unit. I returned the unit and got a replacement, so tonight or soon I'll try wiring it up to see if the fan works -- but this time, I'm testing all the wiring on my workbench before going to the trouble of mounting it up in the attic.
 
  #10  
Old 01-29-14, 01:47 PM
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The wiring diagram does not make sense.
You're right. It doesn't make sense. According to the diagram, when you close a switch, you short out the corresponding device because the left side of all three switches is tied to the yellow wires. Whatever. I'm sure it isn't actually wired like that. I installed one of those for a neighbor last year and he didn't want the night light and was okay with putting the light and fan on a single switch so it was a pretty easy install.
 
  #11  
Old 01-29-14, 02:24 PM
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The fact that thy show a brown wire indicates they don't really understand how most U.S. homes are wired. Most homes are wired with cable which has no brown or yellow. At least the yellow though is a color used in conduit but brown? Wonder what the manufacturer's customer service would say?
 
  #12  
Old 01-29-14, 02:55 PM
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Originally Posted by pcboss View Post
The wiring diagram does not make sense. Nor does it look like any fan/light/nightlight unit wiring I have ever done.
Originally Posted by mossman View Post
You're right. It doesn't make sense. According to the diagram, when you close a switch, you short out the corresponding device because the left side of all three switches is tied to the yellow wires. Whatever. I'm sure it isn't actually wired like that. I installed one of those for a neighbor last year and he didn't want the night light and was okay with putting the light and fan on a single switch so it was a pretty easy install.
No, it makes sense. The power goes directly to the unit, and it has its own low-voltage switch loop.. Think of it like wiring a thermostat (red is the common wire, then white is for heat, yellow is for cool, green is for fan, etc). So in this fan, yellow is the common lead from the transformer, and the red/blue/brown leads are the control trigger inputs from the switches.

Originally Posted by ray2047 View Post
The fact that thy show a brown wire indicates they don't really understand how most U.S. homes are wired. Most homes are wired with cable which has no brown or yellow. At least the yellow though is a color used in conduit but brown? Wonder what the manufacturer's customer service would say?
Most houses don't have blue either, but they use it in ceiling fans for the light connection... Red could have easily been standardized for the light kit, but they went with blue. The color of the field wiring pigtails for hot doesn't necessarily have to correspond to any colors you'd actually find in the field.

And now considering this is Class 2 wiring we're talking about, all logic flies out the window. Colors mean nothing. I can see the thought behind why they did it that way - touching a switch with wet hands in a humid bathroom probably isn't 100% safe, since lights aren't required to be GFCI protected. There may have also been some kind of home automation integration intention in play with the design as well.. But it pretty much kills this fan for any drop-in retrofit application.


OP: Considering that you hooked 120v up to the 24v control wires, you probably fried the control board - which is why the fan wouldn't work.. Since your intention is to have the light and fan wired together anyway.. You can hook it up this way:

Nut the blue, brown, and yellow wires together. Cap the red wire by itself. These wires are low voltage and do not get attached to the house wiring.

Nut the white to white, and black from the switch to black.

Give that a whack. If it does not work, then you can assume that the control board in the fan does not like to be controlled that way and you'll have to choose another model.
 
  #13  
Old 01-29-14, 03:17 PM
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At least the yellow though is a color used in conduit but brown?
Maybe I don't understand your question.

For 3-phase 120/208, black, red, blue. For 3-phase 277/408, brown, orange, yellow?
 
  #14  
Old 01-29-14, 04:30 PM
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Nash: I was talking residential single phase. When I wrote that. I assumed low voltage that I originally suggested had been ruled out but I see Taz has resurrected it with a plausible explanation.

P.S. Only familiar with 480/240 wye (or as I was taught star) and it's been so long I can't remember the colors..
 
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