# vent bathroom fan to furnace vent



## NateHanson (Apr 15, 2007)

Definitely not.


----------



## Keep Em Cool! (Apr 22, 2007)

Of all the forums i have answered questions on, that is the dumbest request ever. Let me lay this out for you! All it takes is a snow storm. Snow gets high enough and blocks the flue discharge. Instead of the furnace's pressure switch shutting down the unit it will just pump into the bathroom fan and kill you and the rest of the family. That will leave you some legacy! Dumb idea. Just plain dumb.


----------



## mikemy6 (Feb 21, 2007)

Throw away youre carbon monoxide alarms too, its gonna be hard enough to get some sleep w/ the ringing headache,and sour stomach. Believe me when the heat kicks on youre gonna wanna take a nap a nice long one. Goobye!


----------



## ron schenker (Jan 15, 2006)

Keep Em Cool! said:


> Of all the forums i have answered questions on, that is the dumbest request ever.


:laughing: :laughing: :laughing:


----------



## pjpjpjpj (Aug 31, 2006)

I agree, this is a horrible idea (I won't call anyone dumb, because, hey, some people have no idea, and it's not their fault they are not familiar with HVAC stuff.... just like I know nothing about cars).

But believe it or not, when I moved into my house a few years ago, this exact thing had been done. The previous owners had had a basement bedroom and bath finished out, and whoever did it ran the 4" flexible (wire coil in plastic) bathroom exhaust fan duct into the unfinished area, made a big loop with it (hanging down from the joists), and then added a Y-fitting to the water heater flue and tied it into that. And the water heater flue actually ran about another 5 feet after that fitting, and then widened to 6" and the furnace tied into it. Of course, this line then went another 5 feet and turned up into the chimney above, running up two floors and out the top of the chimney.

Now, considering that the previous owner's teenage son had lived in that bedroom for several years and not died, I guess they got lucky.... but it certainly was not up to code and I fixed it right away (heck, before I was able to run the toilet exhaust outside, the first thing I did was just let it blow into the unfinished area and take out the Y-fitting from the flue... better to have a little shower humidity in the large unfinished area than to risk carbon monoxide in the basement!).


----------



## jcrampton (Mar 28, 2007)

*thanks for the kind answers*

I didn't think it was a good idea, that's why I asked.

I would have appreciated a little more politeness in your answers.


----------



## cibula11 (Jan 6, 2007)

No doubt. Easy on the responses....it's not like we were all born with the answers. Give the guy a break.


----------



## jcrampton (Mar 28, 2007)

*the only stupid question is the one not asked*

By asking that question, someone else searching this forum might be saved some headaches. That was another reason I posed the question.


----------



## elementx440 (Jan 24, 2007)

Keep Em Cool! said:


> Of all the forums i have answered questions on, that is the dumbest request ever.


and i'm sure you're of great value on "all the forums you answer questions on" calling people's questions dumb. do the world a favor and stick to those forums...




ron schenker said:


> :laughing: :laughing: :laughing:


"However big the fool, there is always a bigger fool to admire him"


anyways, I went to a guys house onetime who had a hot water tank replaced a few years prior in a basement/crawlspace... well I have no idea what happened but the flue pipe was laying on the floor and had never been (I believe) reinstalled since the install. thank god for drafty basements...


----------



## mikemy6 (Feb 21, 2007)

I think that a place like this is great that highly skilled people would take the time to bust your balls your alive and your loved ones what do u think could happen to the people that bought your when u where dead and gone


----------



## jcrampton (Mar 28, 2007)

Nice grammar. I'm not sure exactly what point you were trying to make, but thanks anyway.


----------



## mikemy6 (Feb 21, 2007)

..............,,,,,,,,,,,,,,,,,""""""""""""""!!!!!,!!!!!!;;;;;;;;;;;::::::'''''''''''''''???????


----------



## omahaguy (Oct 12, 2012)

Well, I had the same question and I came here to search for the answer.

I am going to finish my basement and the bathroom will be really close to my furnaces. So I too thought to myself, I wonder if I could run the bathroom vent into the furnace exhaust vent that goes from the basement up to the roof.

So I don't think it was a stupid question.


----------



## bobelectric (Mar 3, 2007)

You could have a backdraft and bring co3 into the house.


----------



## hvac benny (Dec 29, 2009)

bobelectric said:


> You could have a backdraft and bring co3 into the house.


Or even worse, CO. Lol.


----------



## hvac benny (Dec 29, 2009)

omahaguy said:


> Well, I had the same question and I came here to search for the answer.
> 
> I am going to finish my basement and the bathroom will be really close to my furnaces. So I too thought to myself, I wonder if I could run the bathroom vent into the furnace exhaust vent that goes from the basement up to the roof.
> 
> So I don't think it was a stupid question.


There are no stupid questions. The fact that you took the time to ask speaks volumes. Many people that do have the knowledge and years in the trade sometimes forget what it's like to not know certain things, and forget that they haven't always known what they know. Some of these same people also think they know it all, but never stopped to ask these "stupid questions", and in reality only know enough to be dangerous because they overestimate their knowledge.


----------



## Toolturnr (Oct 8, 2020)

I know this is an old post but have same question with different circumstances. My furnace was replaced with a high efficiency one that now vents out the side wall. There is currently nothing hooked to the old flue pipe as water heater has been updated and it also vents out the side wall. In this circumstance with it being just a open flue pipe could it be used for a basement bathroom fan or would things need changed like the outlet on the roof and would a higher volume fan need to be installed to push the air up through that long of a run.


----------



## user_12345a (Nov 23, 2014)

^You should start a new thread.

Unused furnace exhaust pipes do not work well for exhaust fans, etc due to condensation issues. They're designed for very hot flue gas.
To use it, the velocity would have to be very high and or the entire pipe would have to be insulated.

You should just vent out the side of the house with the correct vent. Typical exhaust fans use 4", some larger ones need 5 to 6".


----------



## yuri (Nov 29, 2008)

If it is a double wall B vent then it won't sweat or rust out as there is lots of water in the smoke of a gas furnace.

Heat rises so it likely would work BUT I would not use it. It could freeze up right at the chimney cap outside as that part is uninsulated and if you have lots of cool moisture it could freeze or produce icicles. All depends on where you live and how cold it gets.


----------



## Old Thomas (Nov 28, 2019)

Not a good or safe idea. You get one point for asking before doing.


----------



## Drewwaz (Jul 28, 2021)

Covered my question thanks


----------



## Hombre2021 (4 mo ago)

Keep Em Cool! said:


> Of all the forums i have answered questions on, that is the dumbest request ever. Let me lay this out for you! All it takes is a snow storm. Snow gets high enough and blocks the flue discharge. Instead of the furnace's pressure switch shutting down the unit it will just pump into the bathroom fan and kill you and the rest of the family. That will leave you some legacy! Dumb idea. Just plain dumb.


You're explanation make sense, but just don't call this the dumbest question, because remember questions are asked so we don't make dumb mistakes


Keep Em Cool! said:


> Of all the forums i have answered questions on, that is the dumbest request ever. Let me lay this out for you! All it takes is a snow storm. Snow gets high enough and blocks the flue discharge. Instead of the furnace's pressure switch shutting down the unit it will just pump into the bathroom fan and kill you and the rest of the family. That will leave you some legacy! Dumb idea. Just plain dumb.


----------



## roughneck (Nov 28, 2014)

Hombre2021 said:


> You're explanation make sense, but just don't call this the dumbest question, because remember questions are asked so we don't make dumb mistakes


You just replied to a 15 year old post made by a member that hasn’t posted on this site in an equal amount of time.
Kind of pointless, no?


----------

