Foil-bubble-foil insulation revisited

[TimNY]

There was a prior post about this stuff here.

The installation was failed because even at the R-4.2 (it also states "R-5.6 with airspace"-- that'd be interesting to see on a duct) is claims it provides, it's well below the R-8 NYS requires.

For reference, my code says:

N1103.2.1 Insulation.  Supply and return ducts shall be insulated to a minimum of R-8.  Ducts in floor trusses shall be insulated to a minimum R-6.  Exception: Ducts or portions thereof located completely inside the building thermal envelope.

The specification sheet is here. Is there anything else I should be looking for? I'm skeptical this will provide anywhere near R-4.2, but what do I know.

I'm a bit leary of the "Testing & Certifications" column on p2. Ok, it was tested to ASCM C518-- tested and failed? Or is it certified?

I would appreciate your thoughts. I don't care if they use it, as long as it complies.

Tim

 

[Dr. J]

Re: Foil-bubble-foil insulation revisited

I would say this product does not meet the definition of R-factor in the IRC (or IECC - IECC def used because it is more applicable to duct insulation).

R-VALUE (THERMAL RESISTANCE). The inverse of the time rate of heat flow through a body from one of its bounding surfaces to the other surface for a unit temperature difference between the two surfaces, under steady state conditions, per unit area (h × ft2 × °F/Btu) [(m2 × K)/W]. (emphasis added).

Per the cut sheet, "The product provides an R-5.6 when installed with a 0.375” air gap between the duct and the insulation." Thus the claimed R-value is not from surface to surface. Note that it is required to provide a "candy cane" spacer wrap. What happens when the bubble wrap droops between the spacers? What about at hangers? What is the effective R value with all the thermal bridging of the spacers? It is only a radiant barrier. Air gaps and leakage will allow convective heat transfer. It has almost no conductive resisitance so if it touches a surface (either the hanger or the duct), heat is readily transfered.

Imho, it's all smoke and mirrors. From an AHJ standpoint, I would first point out the obvious - the claimed R5.6 is less than either R-8 or R-6. Then if you still need more ammo (new math, maybe they can show why 5.6 is greater than 8) - use the definition of R-value and ask what is the surface to surface R-value. Then ask for an as-installed R-value considering the thermal bridging of the spacers and hangers.

 

[Heaven]

Re: Foil-bubble-foil insulation revisited

One can include the added airspace counting towards the R value of an assembly, the bounding surfaces being the outermost material(s). All the other drawbacks mentioned are true with insulation of many types (fiberglass for instance) where the installation becomes important to the rated R value.

They should go with two layers. That'd do it. . . .

 

[TimNY]

Re: Foil-bubble-foil insulation revisited

Thank you for the replies.

The current installation consists of the produce wrapped tightly around the ductwork.

Since the wrap was labeled 4.2 and 5.6, I found this specification sheet. It states R-4.2 when installed against the duct. However, it also states not recommended as a stand-alone solution with air conditioning ducts.

I further do not see ASTM C518, the standard listed in there specification sheet, as being a reference standard i my residential code.

Would there be some sort of certification from a 3rd party agency I could ask for? Something that certifies it actually provides R-4.2 when applied directly to the duct. What I have here already will require new insulation to be provided, but I would also like some documentation that this actually provides R-4.2 as defined by the IBC.

Thanks again,

Tim

 

[TJacobs]

Re: Foil-bubble-foil insulation revisited

Tell them that after they remove all this phony product they can use it for packing material.

 

[TimNY]

Re: Foil-bubble-foil insulation revisited

While my gut reaction shares the same sentiment as yours, I am willing to expend whatever effort I have to either prove, or disprove the products claims. Once again this a product I have seen everywhere in surrounding jurisdictions. SO perhaps there is some documentation to it's performance. Or perhaps once again I will be the guy listening to, "in x y and z we can use this"

[aside] The best answer I ever heard when the "xyz jurisdiction lets us use this" was an individual reviewing kitchen exhaust plans in a neighboring jurisdiction. The plans were rejected for one reason or another. The contrator came into the office and said, "in xyz jurisdiction we can use this." Without missing a beat the reviewer said, "you're going to need a lot of duct to get to xyz." [/aside]

I noted there are 3 ICC-ES reports for similar products. However, the reports are for suspended insulation in a wall where there is an airspace on both sides. The reports list ~R-6 in that application.

I have sent a letter to Reflectix asking for test results from an independent testing lab verifying the thermal conductance when the product is directly applied to the surface.

I will let you know what I receive.

Thanks again for the help,

Tim

 

[MechinspMi]

Re: Foil-bubble-foil insulation revisited

This mfg. testified at a product approval hearing in Michigan that as a stand alone without reflective or air space figured into the equation (Michigan ammendment does not allow for either as duct insulation) that it is only a R1.3 value. Increasing the layers has no effect and does not change the R value. I believe I posted this in the last thread also.

 

[Heaven]

Re: Foil-bubble-foil insulation revisited

This mfg. testified at a product approval hearing in Michigan that as a stand alone without reflective or air space figured into the equation (Michigan ammendment does not allow for either as duct insulation) that it is only a R1.3 value. Increasing the layers has no effect and does not change the R value. I believe I posted this in the last thread also.

That sure is counter-intuative. If one layer of something has an R value, it seems that more layers would have a greater r value. That is fishy. the air space alone inside of the bubbles would be counted as (probabaly) r=1.

 

[TJacobs]

Re: Foil-bubble-foil insulation revisited

What is the R-value of air space?

http://hyperphysics.phy-astr.gsu.edu/Hbase/tables/rvalue.html

Maybe the reflective properties help in the reflectance of a heat source, i.e. reflect it back in the duct :lol: ...but I'd bet it doesn't do much for cold.

 

[Dr. J]

Re: Foil-bubble-foil insulation revisited

That sure is counter-intuative. If one layer of something has an R value, it seems that more layers would have a greater r value. That is fishy. the air space alone inside of the bubbles would be counted as (probabaly) r=1.

This stuff is not "insulation". It is a radiant barrier. 2" of fiberglass insulation is indeed twice as good as 1". That is because traditional insulation resists heat conductance. But all this stuff does is resist radiation, the material itself does not do any conductive resistance. It requires an air space to do that.

From the 2009 ASHRAE Handbook of Fundamentals:

Note that reflective foils are only effective if the reflective surface faces an air space, because radiative heat transfer cannot be reduced where there is no air space to allow radiative heat transfer. Also, multiple layers of reflective foil are no more effective than a single layer, unless the reflective surfaces adjoin different air spaces in the assembly.

I believe the R-1.3 number with no air space.

Note that 100% sealing of the duct and the insulation is also required, because any air flow between the insulation and duct will negate the point of a stagnant air space. All the heat that should be trapped would be wiped away by even a slight breeze.

What is the R-value of air space?

Depends on the emittance of the inboard surfaces of the airspace (shiny good, dull bad) the gap distance (big good, small bad), and the direction of heat flow (up bad, down good, horizontal medium).

Maybe the reflective properties help in the reflectance of a heat source, i.e. reflect it back in the duct

BINGO!

but I'd bet it doesn't do much for cold

No difference. Heat flows from higher temp to lower temp. That may happen to be into or out of a duct, but it flows the same.

The best answer I ever heard when the "xyz jurisdiction lets us use this"...

How about "Oh yeah? What is the address of that project? Let me call my buddy Jim over there."

 

[Heaven]

Re: Foil-bubble-foil insulation revisited

Very nice, thank you

 

[D a v e W]

Re: Foil-bubble-foil insulation revisited

Tim, just went through this 2 months ago. They could not make it work correctly without it being labor intense. They finally abandoned it and attached R-8 insulation. :roll:

 

[TimNY]

Re: Foil-bubble-foil insulation revisited

MechInspMI: Yes, you did post that in the other thread. However, unlike the other case, I have a manufacturer and a spec sheet that says "R-4.2 when directly applied" I didn't know exactly what I should be asking for to prove/disprove their claims. But thank you for that information.

Tim, just went through this 2 months ago. They could not make it work correctly without it being labor intense. They finally abandoned it and attached R-8 insulation. :roll:

The GC has to install a total of R-8, so he had some work to do regardless. I spoke with him again and told him he can install R-8 fiberglass and call for inspection, or rely on the claimed R-4.2, install R-4 fiberglass over the top, and call for inspection after there is documentation definitively stating the product provides R-4.2 when directly applied. He chose the former.

He says HVAC sub stated, "I don't understand, I've been using this since 2004 and nobody has ever said anything". Ugh.

No word from Reflectix.. not even an email.

Thanks Again,

Tim

 

[TimNY]

Re: Foil-bubble-foil insulation revisited

Also just found this:

NAIMA on Bubble Insulation