What's The Deal With Combining Vents? - General Discussion - Contractor Talk

What's The Deal With Combining Vents?

 
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Old 02-23-2019, 01:37 PM   #1
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What's The Deal With Combining Vents?


You can run a water heater and furnace through the same roof penetration, but everything I've heard or seen says not to vent bath fans through the same roof jack.

However, I can't seem to find any code article that addresses this.

I've merely heard the fans won't work.

Seems if you have two combustion appliances entering a Y-fitting, 2 fart fans shouldn't be a problem.

I know there have been several threads about this here, but this is a little different.

I'm know about in-line fans as well, and might use one, but this is more over-arching than just one project.
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Old 02-23-2019, 02:01 PM   #2
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Re: What's The Deal With Combining Vents?


Iíve combined them before, Not saying itís right or wrong.

I figured the little flapper valve on the fart fan would somewhat prevent air from the other fan exhausting into the other bathroom rather than outside.

Iím interested to know more as well.


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Old 02-23-2019, 03:02 PM   #3
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Re: What's The Deal With Combining Vents?


Thirty seconds google

IMC 501.2
https://codes.iccsafe.org/content/IM...xhaust-systems
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Old 02-23-2019, 03:06 PM   #4
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Re: What's The Deal With Combining Vents?


One fart fan could force air into the other bathroom, even past the flapper a little.

The fuel burning appliances make a natural draft with their hot exhaust gasses, which actually draw extra air through the other appliance
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Old 02-23-2019, 03:14 PM   #5
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Re: What's The Deal With Combining Vents?


You can't one is an active vent one is a passive vent using heat to create a draft.
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Old 02-23-2019, 03:18 PM   #6
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Re: What's The Deal With Combining Vents?


Quote:
Originally Posted by Seven-Delta-FortyOne View Post
You can run a water heater and furnace through the same roof penetration, but everything I've heard or seen says not to vent bath fans through the same roof jack.

However, I can't seem to find any code article that addresses this.

I've merely heard the fans won't work.

Seems if you have two combustion appliances entering a Y-fitting, 2 fart fans shouldn't be a problem.

I know there have been several threads about this here, but this is a little different.

I'm know about in-line fans as well, and might use one, but this is more over-arching than just one project.
This is the kind of question that makes me really miss my old foil BWalley

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This is why people need to be uber-licensed like me. Let me tell you how many licenses I have, it's a lot. When I went in to get my plumbing license they wondered why because they told me that anytime I'm in the area, **** just doesn't stink.

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Old 02-23-2019, 03:19 PM   #7
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Re: What's The Deal With Combining Vents?


Quote:
Originally Posted by Anti-wingnut View Post
Thank you.

I spend a lot of time in the California Building Code, Residential Code, Plumbing Code, Electrical Code, Fire Code, Green Building Code, Energy Code, Existing Building Code, Historical Building Code, and ADAAG Standards.

Not so much in the California Mechanical Code, as I don't directly work with that stuff much.


The closest thing I found in the California Mechanical Code is the following:

Quote:
504.2 Independent Exhaust Systems - Single or combined mechanical exhaust systems shall be independent of other exhaust systems.
Slightly less than definitive, at least to my mind.

So does this mean you can combine an exhaust system, but than can't combine it again?
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Old 02-23-2019, 03:23 PM   #8
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Re: What's The Deal With Combining Vents?


Quote:
Originally Posted by Inner10 View Post
You can't one is an active vent one is a passive vent using heat to create a draft.
You can't what?

It's allowed in the Code to combine a water heater and a furnace into one stack.
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Old 02-23-2019, 03:24 PM   #9
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Re: What's The Deal With Combining Vents?


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Originally Posted by Anti-wingnut View Post
This is the kind of question that makes me really miss my old foil BWalley
Not sure what your problem is, Hoss, or who the blue f&^k "BWalley" is, but if you don't like the discussion, move along.
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Old 02-23-2019, 03:27 PM   #10
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Re: What's The Deal With Combining Vents?


Quote:
Originally Posted by Seven-Delta-FortyOne View Post
Not sure what your problem is, Hoss, or who the blue f&^k "BWalley" is, but if you don't like the discussion, move along.
No thank you. Not my problem you don't know who BWalley is from CT BITD, nor is the fact you lack a sence of humor.
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Old 02-23-2019, 03:30 PM   #11
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Re: What's The Deal With Combining Vents?


Quote:
Originally Posted by Seven-Delta-FortyOne View Post


The closest thing I found in the California Mechanical Code is the following:


Quote:
504.2 Independent Exhaust Systems - Single or combined mechanical exhaust systems shall be independent of other exhaust systems.
Slightly less than definitive, at least to my mind.
Seems very definitive to me.
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Old 02-23-2019, 03:49 PM   #12
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Re: What's The Deal With Combining Vents?


Quote:
Originally Posted by Anti-wingnut View Post
BWalley is from CT BITD,


No clue what that means.





To the best of my knowledge, I was born without a sense of humor. I certainly have no recollection of ever possessing one.

Not surprisingly, this has turned out to be nothing but a wast of f&^%king time, like most things on CT.

Maybe you should head over to the thread where the handyman wants to cut gun nails down a 1/4 inch with an angle grinder. Might be more your speed.

Those seem to be the type of threads that get all the active discussion here anyway.
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Old 02-23-2019, 03:55 PM   #13
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Re: What's The Deal With Combining Vents?


I gave you the code reference.

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Old 02-23-2019, 04:41 PM   #14
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Re: What's The Deal With Combining Vents?


I actually read the code as allowing 2 bath exhausts to be combined. It's part of ch4, ventilation.

They aren't different types of mechanical ventilation, and ventilation is different from exhaust. Furnaces and water heaters can have actual exhausts.
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Old 02-23-2019, 04:54 PM   #15
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Re: What's The Deal With Combining Vents?


Same issues as venting furnaces into same flu as fireplace or stove


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Old 02-23-2019, 05:13 PM   #16
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Re: What's The Deal With Combining Vents?


My furnace and water heater are on the same vent. There was a fireplace on there also when I bought the place. My HVAC guy told me the fireplace couldn't be vented there.

I don't understand why. Why can WH and furnace share a vent but not the FP?



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Old 02-23-2019, 05:46 PM   #17
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Re: What's The Deal With Combining Vents?


gas exhaust can be combined
fart fans can also be combined (TMK) BUT you would be wise to have both on at same time or use one of those remote / inline ones which pull from all baths at once

You cannot combine mixed exhausts - oil, coal, gas, wood, fart, laundry

think soot, lint, etc... not a good combo
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Old 02-23-2019, 06:17 PM   #18
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Re: What's The Deal With Combining Vents?


For furnaces, water heaters, and wood stoves, the type of fuel used determines if you can run something like a furnace and a wood stove in the same flue. Oil furnaces don't have the same issues as a propane furnace. Last I checked, I could run an oil furnace and wood stove in the same flue, but not a propane furnace.

Oil furnaces just aren't as picky about the draft, they use an air blower and don't tend to have carbon monoxide issues the way propane and natural gas can.
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Old 02-24-2019, 02:07 PM   #19
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Re: What's The Deal With Combining Vents?


Your anger go down now 7 delta?
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Old 02-24-2019, 02:58 PM   #20
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Re: What's The Deal With Combining Vents?


Quote:
Originally Posted by Seven-Delta-FortyOne View Post
You can't what?



It's allowed in the Code to combine a water heater and a furnace into one stack.
What I'm saying is it's a bad idea whether it's allowed or not. If you join actively vented devices to a common pipe they will blow back into the other. Passive venting in a chimney is different they create a natural draft.



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