# UL listed tape used for sealing of mechanical vents



## DMartin (Jul 2, 2019)

In Portland when I was doing my internship they REQUIRED that UL listed tape was used on all mechanical vents that were connected to a gas burning appliance. Is this a IRC thing or an Oregon thing? I have yet to find the requirement in the code.
thank you


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## Pcinspector1 (Jul 2, 2019)

Not sure if this is it or not?
2009 IECC (International Energy Conservation Code)requires sealing, section 503.2.7 & 103.2.

I find that more times than not the tape used in the field is not approved tape for metal duct sealing but it does have a UL listing. What I see has red printing that's for flex-duct applications.


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## Pcinspector1 (Jul 2, 2019)

What I need to see is (UL-181-a) for metal and the HVAC guys are using (UL-181-b) that's for flex duct.

3M makes a -40-425°F tape for flues. I've not seen it used.


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## classicT (Jul 2, 2019)

*603.9 Joints, Seams and Connections*
All longitudinal and transverse joints, seams and connections in metallic and nonmetallic ducts shall be constructed as specified in SMACNA _HVAC Duct Construction Standards‒Metal and Flexible _and NAIMA _Fibrous Glass Duct Construction Standards_. All joints, longitudinal and transverse seams and connections in ductwork shall be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems, liquid sealants or tapes. Tapes and mastics used to seal fibrous glass ductwork shall be listed and labeled in accordance with UL 181A and shall be marked "181 A-P" for pressure-sensitive tape, "181 A-M" for mastic or "181 A-H" for heat-sensitive tape. Tapes and mastics used to seal metallic and flexible air ducts and flexible air connectors shall comply with UL 181B and shall be marked "181 B-FX" for pressure-sensitive tape or "181 B-M" for mastic. Duct connections to flanges of air distribution system equipment shall be sealed and mechanically fastened. Mechanical fasteners for use with flexible nonmetallic air ducts shall comply with UL 181B and shall be marked "181 B-C." Closure systems used to seal all ductwork shall be installed in accordance with the manufacturer's instructions.
*Exception: *For ducts having a static pressure classification of less than 2 inches of water column (500 Pa), additional closure systems shall not be required for continuously welded joints and seams and locking-type joints and seams of other than the snap-lock and buttonlock types.​


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## classicT (Jul 2, 2019)

...or from the IRC. (IMC above)

*M1601.4.1 Joints, Seams and Connections*
Longitudinal and transverse joints, seams and connections in metallic and nonmetallic ducts shall be constructed as specified in SMACNA HVAC_ Duct Construction Standards‒Metal and Flexible_ and NAIMA_ Fibrous Glass Duct Construction Standards_. Joints, longitudinal and transverse seams, and connections in ductwork shall be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems, liquid sealants or tapes. Tapes and mastics used to seal fibrous glass ductwork shall be _listed_ and _labeled_ in accordance with UL 181A and shall be marked "181A-P" for pressure-sensitive tape, "181 A-M" for mastic or "181 A-H" for heat-sensitive tape. 

Tapes and mastics used to seal metallic and flexible air ducts and flexible air connectors shall comply with UL 181B and shall be marked "181 B-FX" for pressure-sensitive tape or "181 BM" for mastic. Duct connections to flanges of air distribution system equipment shall be sealed and mechanically fastened. Mechanical fasteners for use with flexible nonmetallic air ducts shall comply with UL 181B and shall be marked 181B-C. Crimp joints for round metallic ducts shall have a contact lap of not less than 1 inch (25 mm) and shall be mechanically fastened by means of not less than three sheet-metal screws or rivets equally spaced around the joint. 

Closure systems used to seal all ductwork shall be installed in accordance with the manufacturers' instructions. 

*Exceptions:*

Spray polyurethane foam shall be permitted to be applied without additional joint seals.
Where a duct connection is made that is partially inaccessible, three screws or rivets shall be equally spaced on the exposed portion of the joint so as to prevent a hinge effect.
For ducts having a static pressure classification of less than 2 inches of water column (500 Pa), additional closure systems shall not be required for continuously welded joints and seams and locking-type joints and seams of other than the snap-lock and button-lock types.


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## DMartin (Jul 2, 2019)

well I was able to find in M1601.4.1 of the 2012 IRC says unlisted tape is not to be used on any duct. So I guess I'm going to have to be the bad guy on this situation, There was no marking on the tape itself to signify that is was a listed product. unless he can produce the roll to prove it to me. In Portland it had to be marked on the tape. I wasn't sure if it was a code requirement or not but now I know. Great way to start my second inspection in a new town.


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## DMartin (Jul 2, 2019)

it logged me out and I missed the last few posts thanks guys


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## classicT (Jul 2, 2019)

DMartin said:


> well I was able to find in M1601.4.1 of the 2012 IRC says unlisted tape is not to be used on any duct. So I guess I'm going to have to be the bad guy on this situation, There was no marking on the tape itself to signify that is was a listed product. unless he can produce the roll to prove it to me. In Portland it had to be marked on the tape. I wasn't sure if it was a code requirement or not but now I know. Great way to start my second inspection in a new town.


The UL listing requires that it be printed on the tape. Any listing provided will be in error if the tape does not have the marking.

All UL listed products will have the UL mark permanently affixed.


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## mtlogcabin (Jul 2, 2019)

DMartin said:


> REQUIRED that UL listed tape was used on all mechanical vents that were connected to a gas burning appliance.





DMartin said:


> I have yet to find the requirement in the code.



You can't find it because it is not a code requirement.
First off you do not use the mechanical code you should be using the fuel gas code
Second what type of mechanical vent system is it. It makes a difference in what you look for during an inspection.

2012 IFGC
VENTING SYSTEM. A continuous open passageway from the flue collar or draft hood of an appliance to the outside atmosphere for the purpose of removing flue or vent gases. A venting system is usually composed of a vent or a chimney and vent connector, if used, assembled to form the open passageway.
*Forced-draft venting system*. A portion of a venting system using a fan or other mechanical means to cause the removal of flue or vent gases under positive static vent pressure.
*Induced draft venting system*. A portion of a venting system using a fan or other mechanical means to cause the removal of flue or vent gases under nonpositive static vent pressure.
*Mechanical draft venting system*. A venting system designed to remove flue or vent gases by mechanical means, that consists of an induced draft portion under* nonpositive static pressure* or a forced draft portion *under positive static pressure.*

503.3.3 Mechanical draft systems.
Mechanical draft systems shall comply with the following:
1.   * Mechanical draft systems shall be listed and shall be installed in accordance with the manufacturer’s installation instructions for both the appliance and the mechanical draft system.*
2.    Appliances requiring venting shall be permitted to be vented by means of mechanical draft systems of either forced or induced draft design.
3.    Forced draft systems and* all portions of induced draft systems under positive pressure during operation shall be designed and installed so as to prevent leakage of flue or vent gases into a building.*
4.    Vent connectors serving appliances vented by natural draft shall not be connected into any portion of mechanical draft systems operating under positive pressure.
5.    Where a mechanical draft system is employed, provisions shall be made to prevent the flow of gas to the main burners when the draft system is not performing so as to satisfy the operating requirements of the appliance for safe performance.
6.    The exit terminals of mechanical draft systems shall be not less than 7 feet (2134 mm) above finished ground level where located adjacent to public walkways and shall be located as specified in Section 503.8, Items 1 and 2.

Why in the world are they teaching you to use tape to seal a mechanical draft system on a gas fired appliance when it does not meet code or the manufactures installation instructions.


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## classicT (Jul 2, 2019)

mtlogcabin said:


> You can't find it because it is not a code requirement.
> First off you do not use the mechanical code you should be using the fuel gas code
> Second what type of mechanical vent system is it. It makes a difference in what you look for during an inspection.
> 
> ...


I think he meant supply and return ducts given his previous responses. Exhaust vents for combustion gases is a different animal entirely, as you pointed out.


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## DMartin (Jul 2, 2019)

I asked the question all wrong I apologize. I am looking at a hot water heater venting system that has a forced air vent coming from the furnace and a natural draft coming form the hot water heater. they are connected to the same exhaust vent. the previous inspection failed because they connected it into a down sized exhaust vent. I asked this question because I was on the ride along and saw that the tape they had there was not labeled further down the run. They took it out and connected the two into a wye type connection and got rid if the original downsized vent setup. so now I have another question. They fastened it properly with screws at thirds. But they did not seal it with mastic or anything at the furnace and hot water heater connections. Is this correct?  Forgive me I have done structural work most of my life and mechanical and fuel/Gas is something I am still learning. This is not a final approval luckily but for the future I would like to know. this is a never ending learning process.


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## DMartin (Jul 2, 2019)

mtlogcabin said:


> You can't find it because it is not a code requirement.
> First off you do not use the mechanical code you should be using the fuel gas code
> Second what type of mechanical vent system is it. It makes a difference in what you look for during an inspection.
> 
> ...


They were not teaching me. I remember this being an issue on some of the ride alongs I did when I was doing my internship not necessarily on a gas fired heating appliance. but they were making a fuss about the tape not being printed with UL listing. This is an old house with and old exhaust venting setup they had tape down the run from the furnace and the H.W. I am a noob at this still.


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## mtlogcabin (Jul 2, 2019)

DMartin said:


> I am looking at a hot water heater venting system that has a* forced air vent *coming from the furnace *and a natural draft *coming form the hot water heater.



It will not work and is not code compliant,  unless both appliances are either positive static pressure or negative static pressure you cannot mix a natural draft appliance with a positive pressure draft system.

2012 IFGC
501.6 Positive pressure.
Where an appliance equipped with a mechanical forced draft system creates a positive pressure in the venting system, the venting system shall be designed for positive pressure applications.


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## classicT (Jul 2, 2019)

DMartin said:


> I am looking at a hot water heater venting system that has a forced air vent coming from the furnace and a natural draft coming form the hot water heater.


Whoah...major issues. Cannot connect a forced air and natural draft. It will push exhaust back towards the water heater.


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## DMartin (Jul 2, 2019)

Well looks like they will be running another setup. I am just a bystander on this inspection but I am trying to learn the rules. so what about sealing of the seams is this required?


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## DMartin (Jul 2, 2019)

Thought this was going to be my inspection but I guess not. He just wanted me to go make sure they had a wye setup. I'm glad this is not mine now I'm not ready for these yet. Will need to learn more on these before I do them on my own.


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## DMartin (Jul 2, 2019)

And I guess they have a permit to do an induction furnace that's why it's not final inspection.


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## ADAguy (Jul 2, 2019)

Hang in there, we all started once and have never stopped learning.


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## Paul Sweet (Jul 3, 2019)

Not all induced draft furnaces create positive pressure.  Check the furnace installation instructions.


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