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Vent Termination


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I posted this same photo a few days back and got some helpful responses, but I'm re-posting this with the hope of hearing from some of the HVAC pro's that regularly contribute here. In my report I stated:

"I have rated this category marginal in order to point out the following observation regarding the termination position of the furnace vent:

- The International Residential Code (IRC) & the Uniform Mechanical Code (UMC) require that category IV forced vents (the type that is used by this home's furnace) terminate a minimum of 4' below or to side of windows. The window adjacent to this appliance vent does not have these clearances.

NOTE: As with all codes, these codes can be superceded by the manufactures installation instructions and listings. I did not have the opportunity to review this documentation. I recommend that the termination point of this vent be verified to comply with Rheem's window clearance recommendations for this furnace.

NOTE: As the window will likely never be open when the furnace is on, the hazards associated with this are minimal."

My Questions - Was I right in my statement regarding the manufactures installation instructions taking precedent over these codes? Does this type of exterior vent cap actually make this safer than standard pvc pipes? I did an online search but couldn't come up with anything that would validate the safety of this installation. Is it unreasonable to suggest that the builder produce documentation verifying that this furnace is safely vented per manufactures installation instructions? I'm taking crap from the builder - demanding to see my NYS license and my ASHI certification, etc....

Any advice on how I should have addressed this observation?

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20079373927_Vent%20Termination.jpg

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I think you said way too much, Dave. You could have simply left it at, "The furnace flue-pipe is improperly terminated too close to a window." You're the expert, and you don't need to confuse the issue by bringing up the jazz about the manufacturer's installation instructions. If the builder wants to contradict what you said, the onus is on him to produce references that the flue pipe is okay as is.

And what if you're wrong and Rheem differs from the IRC? Big deal. Explain to your client why you said what you did.

As for the builder, screw him. You don't owe him an explanation or anything else.

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Bain was correct your wording was way to much. You were also correct as to the 4' clearance rule. The termination cap from what I have seen is ok just too close to the window and the A/C unit. I have seen windows open in the middle of the winter with the furnace working so the statement that the window will never be open when the furnace is on is not correct. Case in point a family gathering with a large crowd puts off some good heat and possible smoke, so one might open a window to vent. The termination vent is called a Bay-vent. I have seen and installed them many times in the past. I hope this helps.

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Thanks for your reviews and responses. Someone e-mailed me an illustration from a training manual today from one of the inspector training schools. I'd post it, but I don't want to risk violating any copyright issues. The illustration is titled "Improper sidewall vent locations - high efficiency furnaces" It shows a HE vent installed directly beneath a window and is captioned "3' clearance (if > 100,000 BTU) - 1' clearance (if < 100,000 BTU)"

That's it - it does not mention if these clearances are beneath, to the side, or over. Has anyone out there reading this post seen this illustration? This is from one of the most reputable training schools. Any opinions on this?

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You need to find out from the manufacturer what they require. Simple call or email their technical desk and they will answer your question. I bet you can even download the installation guidelines. You should be the one providing the documentation to backup your findings, not the builder.

I don't think the condenser unit is not going to cause any problems.

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Hi,

Yeah, I agree, call the manufacturer. With few exceptions, I seem to have really good luck contacting various manufacturers and organizations directly. Yesterday I spent about 3 minutes on the phone with a guy and found everything I needed to back up what I was reporting on a home.

OT - OF!!!

M.

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Originally posted by dtontarski

. . . My Questions - Was I right in my statement regarding the manufactures installation instructions taking precedent over these codes?

Not really. I suppose that, in theory, if a code section and a manufacturer's instruction were to be in conflict, the manufacturer's instruction would rule. However, that's an extremely rare occurance. In fact, I can't think of a single instance of it.

What happens more often is that the code provides a general rule and the manfuacturer provides more specific instructions that fall within the code bubble.

Does this type of exterior vent cap actually make this safer than standard pvc pipes? I did an online search but couldn't come up with anything that would validate the safety of this installation.

Yes. That cap tells you that you're looking at a direct vent terminal, not just a cat IV vent. If it's connected to a furnace that's over 50K btu/hr, that vent can be within 12" of a window. Check out G2427.8, Exception 3.

Is it unreasonable to suggest that the builder produce documentation verifying that this furnace is safely vented per manufactures installation instructions? I'm taking crap from the builder - demanding to see my NYS license and my ASHI certification, etc....

You're lucky he didn't set the dogs on you. You're wrong here. Sadly, the builder probably doesn't even really know that you're wrong and he's bluffing. But eventually he'll find out. Then you better watch out for the dogs.

Any advice on how I should have addressed this observation?

Personally, I would have just glanced at it and walked on by. . .

- Jim Katen, Oregon

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The International Residential Code (IRC) & the Uniform Mechanical Code (UMC) require that category IV forced vents (the type that is used by this home's furnace) terminate a minimum of 4' below or to side of windows.

I don't think that is correct.

It seems to me that there's a few folks that might be applying the rules for "mechanical draft venting system" terminations to the vent terminal of a "direct-vent appliance".

Use this illustration, not the one from the school:

200796174525_venterminations.JPG%20

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Originally posted by Bain

What's exception 3, Jim? Kentucky adopted a state code--which completely deleted the fuel gas section--back in 2002, and I don't even know where my old copy of the IRC is.

John

Bill Kibble's illustration pretty much sums it up.

Exception 3 just says that direct-vent appliance vents can terminate much closer to building air openings than other appliance vents can.

The reason, I think, is that direct-vent appliances are uncoupled; they don't depressurize the building in the way that non-direct-vent appliances do. So it's safer to allow the exhaust openings closer to the windows. I'm not sure that this explanation makes sense, but it's the reasoning that I've heard.

- Jim Katen, Oregon

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I hope that folks are still following this thread...

Jim K stated: "That cap tells you that you're looking at a direct vent terminal, not just a cat IV vent."

Can someone share with me basic definitions for Category IV versus Direct Vent? - How do I recognize direct vents versus "just a cat IV vent?"

Thanks.

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Originally posted by dtontarski

I hope that folks are still following this thread...

Jim K stated: "That cap tells you that you're looking at a direct vent terminal, not just a cat IV vent."

Can someone share with me basic definitions for Category IV versus Direct Vent? - How do I recognize direct vents versus "just a cat IV vent?"

Thanks.

A category IV appliance might or might not be direct vent. In order to be classified as direct vent, it has to be uncoupled. That is, it has to take all of its combustion air from the outdoors and vent all of its exhaust to the outdoors. When it does this, it has no effect on the pressure inside the building. You can recognize a direct vent setup by the two pipes; one for supply and one for exhaust.

- Jim Katen, Oregon

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