two bathroom fans, 1 3" exhaust - feasible?

[Chrisatunc]

Howdy-

I have a small shower room (5*5) and a small toilet/sink room (5*5). A fan exists in the toilet room but I want to add a fan to the shower room, too.

My idea was to install the second fan and make a T with the existing exhuast pipe of the existing fan. I am going to make both fans come on at the same time; I will be setting up 3-way switches in each room to make this happen. I have a book showing me how to set up the wiring and I have a post going on the electrical forum to make sure that the GFCI-above-the-shower part is covered.

Here, though - since I will be using low-volume fans, can I 'get away' with putting two fans with 3" exhausts into one 3" pipe going through the roof?

-Chris

[Andrew]

I do not think this would be a good solution. Both fans will be working against each other, and 3" is only used for small bath fans.
You might be better off to use an inline fan with two intakes, one for each area.

[Ed Imeduc]

To each his own. Each needs their own vent to outside.

ED ;)

[hth]

This is samething I am thinking in my head and about to post. I am thinking of having 2 fans installed and sharing one 4 inch vent. Would it be working in my case when I use 4 inch vent? I hate cutting one more hole in the roof :-). Does the code allow 2 fans sharing 1 vent?

Thx.

[Andrew]

hth-
It is not against code to vent two bath fans through the same duct. Good practice dictates that it may not be a good idea, since you are trying to send two 4" pipes into one 4" pipe. As I said before, a much better approach would be to buy one in-line fan, and duct the two intakes to the areas you wish to exhaust.

[djwcaw]

I'm about to tap the output of my basement bathroom exhaust fan to the 4inch duct from my main level powder room exhaust fan that expels out the back of my home. I'm using a T connector along with two plastic backdraft/flapper inserts (they are labeled as dryer vent.) Therefore when one exhaust fan is operational the flapper will be closed to the other and all air directed towards the output. Anyone see a problem or code issue with this? Or with using the plastic vents inline? TIA.

[Ed Imeduc]

Thats not the right way to do it. But ask code there might be you cant sell the home later on, with thatset up in it?


ED ;)

[sorensenj]

I've been looking at systems that allow two intakes going to one outlet for my bathroom. It looks like a person could use an inline fan with a 'tee' allowing two seperate areas (could be two intakes in the same room, could be two different rooms, the Fantech site shows both) to be exhausted through one vent to the outside. Look at Fantech.com or Nutone.com for ideas on this. But check your area codes first to see what is allowed.

[scottg]

sorensenj
You got the right one baby!!!!!!!!
These are the way to go.
I have installed ten or so and the only thing I have against these are that they are too quiet. Some times I like to here the sound of the fan when I am on the can.

[sorensenj]

I hear ya Scottg! I had to put a timer on my fan so it would shut off by itself. We found we left the fan running all night at times because you couldn't hear the darn thing running!

[jim97219]

Chrisatunc,

Sorensenj and Scottg have nailed your solution. I have one and it works quite well. Mine mounts in the attic and has plenty of CFM to ventilate both bathrooms. Given that the unit is up in the attic and not directly over the shower, I think you can mount it above the shower without needing a GFCI. Sparkies, please correct me if I'm wrong, but I think you put the vent directly above the shower without the need for a GFCI given that the motor and elecricity are not directly overhead.

I put a one-hour timer (Intermatic FD60MC) in each bathroom wired in parallel (I think that's the correct term). Anyway, the fan stays on until both timers have timed out. I went with 1-hour timers not because I want vent the bathrooms for an hour but because one flick of the knob is a natural thing to do when you turn it on. That flick gets you a third of a turn, 20 minutes' worth, which is about right.

Mine is made by Spruce but Nutone and Panasonic both offer them. It came in a kit with nearly everything you need for venting two bathrooms. Missing was the duct and some hose clamps. I used 4" fiberglass-insulated flex line and it was easy to work with and does the job. Oh, I took the sales guy's advice and hung the fan from a rafter using some 3/16" nylon cord, long 3/16" threaded rod and mending plates instead of using the mount-it-to-a-stud hardware that comes with the unit. Why? Quieter still; no resonation of the motor through the house via the trusses, etc.

Last, you'll just have to figure out how to vent it out of the house; don't vent it into the attic as you'll get a mold problem in due time. I've got mine going out via a roof vent. I suspect others here would suggest I put in something that would attach to the duct and vent it out through the roof but that's how I did it.

Good luck and keep us posted on how it turns out!

Jim

[Andrew]

FWIW-
That is the solution I mentioned in the first reply :)
Fantech makes a good one.
www.fantech.net