Wiring a "central" bathroom exhaust fan

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Old 11-24-03, 01:46 PM
bikeracer
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Question Wiring a "central" bathroom exhaust fan

I am thinking about purchasing a "central" exhaust fan to be mounted in my attic to replace two dead or dying bathroom exhaust fans. I have heard you can use more powerful fans and they are much quiter since they are mounted away from the bathroom itself. My question is how do I wire the switches in each bathroom to activate the fan? Would I wire them just a you would a 3-way light fixture with the fan replacing the light in the circuit? I also was thinking of purchasing a central exhaust fan which allows 4 duct inputs. This would allow me to convert my non-exhusting kitchen fan to a system with a duct to take the cooking odors outside. If I did this would I wire the circuit as a 4-way switch? Thanks in advance for any and all help
 
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Old 11-24-03, 02:03 PM
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I have never heard of a central exhaust fan, so I am not familiar with them, but I will try to answer your questions.

To control something with more than one switch requires two three-way switches for two of the switch locations and then a four-way switch for each additional location. However, these switches control power only. If the device you have is simply an on/off fan controlled by input power then this will work. However, if this device runs off 220 and/or is controlled by low voltage switches then you will have additional considerations.

Several concerns that I have are as follows: It sounds like this device may require a separate circuit. You may have to run new wire from the panel to power it. Using three-way and four-way switches requires additional wires, and probably to a new location. You will likely be running new wires to each switch location. You also have the difficulty in running duct work, but that is not an electrical issue.
 
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Old 11-24-03, 02:35 PM
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We usefan-Tec brand and they are top qualityand extremely well made. I highly recommend them.
To wire them we run two switch legs, one to each room and wire the single pole switches in parallel. This way there is no confusion as to if the fan is on or not. Either switch in the "on" position means the fan is on.
They have a kit meant just for two bathrooms. It's around $220. Less than two "quiet" Nutone's.
 
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Old 11-25-03, 12:11 PM
bikeracer
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Central Exhaust fan..more questions

Thanks for the replies guys.... Speedy Petey I think you are on the right track for what I need. I checked out the FanTech site and they seem to have the solutions I'm looking for. I'm still a little unsure of the wiring set-up though. You say you use 2 single pole ( as opposed to 3-way or 4-way) switches. This is what I currently have controlling the 2 individual fans in each bathroom right now. Are you saying that I would just wire each switch to the fan individually(parallel) such that each switches two leads ( hot and neutral ) would each be connected to the corresponding hot and neutral leads on the fan? I thought of this type circuit originally but I was worried that it creates the weird situation where both sides of the OFF switch are hot when one switch is on and the other is off. I'm not an electrician (obviously) but I thought this situation might not be desirable (or allowed by code) Even though both sides of the switch are at the same potential. But what do I know! Thats why I'm asking. I assume the kit comes with the duct tee for connecting two ducts to one fan. I guess I could splice in a third duct from the kitchen if the fan has enough capacity and the wiring is done as I think I understand you to mean. I hope I can wire things your way because that saves a ton of wire fishing and pulling to get a new wire with a traveller lead pulled to all switches. Do you know where I can buy the FanTech fans here in Western NY? Thanks alot for all your help!!!
 
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Old 11-25-03, 12:24 PM
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UH...... if you parallel the switches they need to be on the same phase or turning both switches on simultaneously would cause a phase to phase short....right

Seems to me you would have to make sure that both exixting fans were on the same phase.
 
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Old 11-25-03, 12:44 PM
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I would think you'd want to make sure both switches are on the same breaker as well. Other wise, you would have to turn off power to both when working on either circuit. Might be okay for you, but could be a dangerous situation for the next owner...

Might also want to check code on the kitchen exhaust. As an X-fireman I wouldn't feel comfortable venting a kitchen fan into anything central. If it's going to go outside, it needs to go directly outside.


Doug M.
 
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Old 11-25-03, 02:21 PM
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First off, I would NOT tee off to a kitchen hood!! I don't think this would meet building code and Is quite unsafe. Also I don't think the fan is approved for kitchen use. Maybe they do have one, I'm not sure.

Let's see if I can explain this one. I think everyone is a little confused at how I described it.
Take your typical feed at the fan. Then for a switch you would just run a two wire down to the switch. Now just do this twice, once more to the other room. Same feed, just two switch loops, in parallel.
 
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Old 11-25-03, 03:12 PM
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Why would you want to put two switches in parallel? I understand how it would operate, but personally I would rather have the ability to turn the fan on or off from either location, not just on from either location.
 
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Old 11-25-03, 03:22 PM
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Wiring it this way lets someone in either room turn on the fan. If either switch is on the fan is on but both have to be off for the fan to be off. This way someone in one room cannot inadvertantly turn off the fan if someone is in the other room.
It's a much better situation than a 3-way where the switch can be up or down and you can't tell if the fan is on. They are basically silent.
 
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Old 11-26-03, 10:37 AM
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More on Central bathroom exhust fan..

First of all thanks for your help guys.
Salient points so far:
- Do Not tee kitchen exhust with other fans..Got it
- Run parallel switches to fan from each bathroom so switch in ON position truly means fan is ON
The only question I have is still the same one I considered and discarded when I decided to use the forum. Is it safe and allowable by code to allow 2 switches to be wired in parallel off the same hot pole of the fan such that turning one on makes both sides of the other switch HOT. I hope I'm interpreting your description of 2 parallel switches correctly Speedy Petey. I don't really understand the consideration of phase someone mentioned but I agree that it does make it dangerous for someone servicing one of the switches who is not aware of the circuit( this is why I thought it might violate code) If 2 parallel switches is not the way to go is there a way to do this with a muti-pole relay of some kind? That would sure beat re-wiring. Sorry to belabor this discussion guys I just want to know what kind of job I have ahead.
 
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Old 11-26-03, 10:55 AM
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Is it safe and allowable by code to allow 2 switches to be wired in parallel off the same hot pole of the fan such that turning one on makes both sides of the other switch HOT.
Yes, if, as Doug said, you are talking about two hots from the same circuit (not just the same leg of the power). If your existing bath fan switches are not already on the same circuit, it will be trivial to make that so. Since there must be a cable running from the new fan to each switch anyway, just make them all switch loops with power going first to the fan.
 
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Old 11-26-03, 01:33 PM
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Exactly!
 
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Old 08-31-09, 04:56 PM
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Hey Guys,

Since my B/R ceilings are artistically textured, I do not want to disturb the ceilings by removing the existing ceiling fan finish bezels and motor boxes. So, I was thinking of "gutting" the fixtures by removing the motors and connecting the existing exhaust ports to the FanTech unit. Does anyone see any issues with my doing this?
I like the parallel switch idea presented here earlier.

Thanks!
 
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Old 09-01-09, 09:36 AM
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Originally Posted by Abuello View Post
Hey Guys,

Since my B/R ceilings are artistically textured, I do not want to disturb the ceilings by removing the existing ceiling fan finish bezels and motor boxes. So, I was thinking of "gutting" the fixtures by removing the motors and connecting the existing exhaust ports to the FanTech unit. Does anyone see any issues with my doing this?
I like the parallel switch idea presented here earlier.

Thanks!
The issue with doing that is getting the desired air flow. I am no HVAC pro, but I suspect if one exhaust duct is significantly longer than the other, you would want to restrict the shorter duct so the fan will pull more air from the longer duct. Also, you might want to compare the cross-sectional area of the fan's suction side to the multiple outlets from the old fan housings. For example if you have a 6" diameter inlet, the total area of the old housing outlets should be the same or more than the area of the 6" duct for best efficiency.

I have a Fantech 6" roof-mount serving my wife's art studio and an upstairs bathroom. Each room has a 4" flex duct to a 6x4x4 Y attached under the roof. It's been in service since 2001. It's got a very quiet German motor that weighs a ton. It usually runs 24x7 at a low speed and it's one of my favorite features of the house. No fogged mirror EVER.
 
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