# Settle this argument.



## Morning Wood (Jan 12, 2008)

Running ductwork for HRV in my house. Using alot of round pipe and oval pipe. I say to tape the seams of the pipe itself. My father says it isn't necessary and you only need to tape the joints. Needless to say we don't know. I say better safe than sorry. It's HRV only. Not AC or heat. Thanks, Nick.


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## jaydee (Mar 20, 2014)

My vote = tape seams and joints


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## Inner10 (Mar 12, 2009)

Morning Wood said:


> Running ductwork for HRV in my house. Using alot of round pipe and oval pipe. I say to tape the seams of the pipe itself. My father says it isn't necessary and you only need to tape the joints. Needless to say we don't know. I say better safe than sorry. It's HRV only. Not AC or heat. Thanks, Nick.


Neither is necessary if you fit your pipes together properly.


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## hdavis (Feb 14, 2012)

Tape both, they aren't air tight unless you do.


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## Dan_Watson (Mar 1, 2008)

Seams and joints.


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## avenge (Sep 25, 2008)

Seems a little overkill to do the seams, but why not, certainly can't hurt.


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## Morning Wood (Jan 12, 2008)

Inner10 said:


> Neither is necessary if you fit your pipes together properly.


What if it was heat or AC? Would your answer be the same?


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## Inner10 (Mar 12, 2009)

Morning Wood said:


> What if it was heat or AC? Would your answer be the same?


Absolutely


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## hdavis (Feb 14, 2012)

These requirements apply to materials for the fabrication of air duct and air connector systems for use in accordance with the International Mechanical Code (IMC), International Residential Code (IRC), and Uniform Mechanical Code (IMC), Standards of the National Fire Protection Association for the Installation of Air-Conditioning and Ventilating Systems, NFPA No. 90A, and the Installation of Warm Air Heating and Air-Conditioning Systems, NFPA No. 90B. 1.1 revised October 27, 2008 [13][14]

Joints of duct systems shall be made substantially air-tight by means of tapes [e.g. duct tape rated to withstand the temperatures involved - Ed], mastics or gasketing.


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## TNTRenovate (Aug 19, 2010)

Even if properly installed you will have air loss at seams and joints. It's always recommend to tape all joints and seams.


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## Inner10 (Mar 12, 2009)

The only time any house here gets it's ducts taped or painted with mastic is when it's run through an un-heated space such as an attic, or is a commercial installation with large spiral duct. 

Sure all seams and pipes leak, but they don't leak much and the "leaked" air isn't wasted it's still contributing to heating or cooling your living space.

A properly fitted duct shouldn't leak much, and when they are fitted properly a single screw is all that is required to hold them together. I'd take a good clean HVAC install without tape over one with over-crimped ends rammed together at every angle, skewered with 5 screws and wrapped with a mile of foil tape any day.


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## TimelessQuality (Sep 23, 2007)

What's HRV?


Return air?


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## BadgerBoilerMN (Sep 10, 2010)

My father was a commercial tinner and taught me to make good tight joints. Still a good skill today and should not be overlooked. But certainly "old school" since the ICC requires tapes joints. 

If we compare tin to hydronic piping one could ask how much leaking would be OK in you pipe joints. If the loss is in the envelope it is not the loss of conditioned air, rather the loss of efficiency. The blower must work harder to deliver the same amount of energy. 

Tape them all fellas.


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## TNTRenovate (Aug 19, 2010)

Inner10 said:


> The only time any house here gets it's ducts taped or painted with mastic is when it's run through an un-heated space such as an attic, or is a commercial installation with large spiral duct.
> 
> Sure all seams and pipes leak, but they don't leak much and the "leaked" air isn't wasted it's still contributing to heating or cooling your living space.
> 
> A properly fitted duct shouldn't leak much, and when they are fitted properly a single screw is all that is required to hold them together. I'd take a good clean HVAC install without tape over one with over-crimped ends rammed together at every angle, skewered with 5 screws and wrapped with a mile of foil tape any day.


Great, we should do it the way it's done there instead of the best way. :thumbsup:

If the seams leak in the cavities it's not better than having that air in the living space. I would rather pay to condition the living space rather than a wall or floor cavity. 

You should strive to give your customer the best installation possible. Sealing the seams doesn't add that much time or cost to the project and in the end you have a better more efficient system.

And I would never just use one screw. All joints get at least two if not three screws. Tape and then screw them together that's the proper way to install a system.


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## Inner10 (Mar 12, 2009)

TimelessQuality said:


> What's HRV?
> 
> 
> Return air?


Heat recovery ventilator, it's a heat exchanger for fresh air. Normally you see them suspended beside a furnace with a mess of flexible insulated duct work. Typically in your way of running wires. 



TNTSERVICES said:


> Great, we should do it the way it's done there instead of the best way. :thumbsup:
> 
> If the seams leak in the cavities it's not better than having that air in the living space. I would rather pay to condition the living space rather than a wall or floor cavity.
> 
> ...


The "best way" is not always the most efficient or effective. If something has an almost negligible payback with a significant up front cost then why do it?

If your duct needs more than a single screw it's not fitted properly.


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## MarkJames (Nov 25, 2012)

Taping the seams of round duct is a bit overkill. But all joints, seams of rectangular ducts, etc. definitely.


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## hdavis (Feb 14, 2012)

Just a recap - the question is "How bad is still good?"

Who wants to do duct leak testing to make sure their bad install meets whatever max leakage they spec for the system (and still doesn't meet US meet / AC installation codes). 

I'd be some kind of thrilled to have to go back in after all the finish work is done and actually seal a system because a poor install allowed the filter to be bypassed and clogged the heat exchanger.

Good is good, everything else isn't.


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## Inner10 (Mar 12, 2009)

hdavis said:


> Just a recap - the question is "How bad is still good?"
> 
> Who wants to do duct leak testing to make sure their bad install meets whatever max leakage they spec for the system (and still doesn't meet US meet / AC installation codes).
> 
> ...


How would not taping a round duct cause a filter to get bypassed?


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## MarkJames (Nov 25, 2012)

On topic:

http://www.greenbuildingadvisor.com/blogs/dept/musings/sealing-ducts-what-s-better-tape-or-mastic


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## hdavis (Feb 14, 2012)

Inner10 said:


> How would not taping a round duct cause a filter to get bypassed?


Any air entering through seams, joints, holes has bypassed the filter, as opposed to "filter bypass", which I've always used to mean the air that bypasses the filter at the filter holder. Semantics, maybe...


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