# Reflectix insulation on ducts?



## Brian26 (Feb 4, 2017)

My wife's cousin gave me 2 rolls of 48" x 100" of it for free. He is an HVAC tech and said it was left over from a job they did. I started to wrap my ducts with it but have read mixed reviews on it. I am installing it with the recommended air gap to get R6.

The unit is a Carrier Infinity heat pump/ac with an oil fired backup when the heat pump can't keep up.

Has anyone used it before?


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## Greenmonster304 (Feb 4, 2017)

I have installed miles of it.  It is very popular here on new installations.  It works pretty well but more importantly seal all your joints first.


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## Brian26 (Feb 4, 2017)

Greenmonster304 said:


> I have installed miles of it.  It is very popular here on new installations.  It works pretty well but more importantly seal all your joints first.



This has to be one of the most labor intensive projects on the house....

I sealed everything with Ul 181 metallic tape and used mastic on the angled duct joints. That alone made a huge difference. 

I used my Flir to see if the first 6 feet was worth the effort and it does seem to be effective. I measured a 30-40 degree difference between insulated and non-insulated duct.


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## Greenmonster304 (Feb 4, 2017)

Usually ducts are insulated before they are hung.  At least in new residential installations.  Commercial installs sometimes they hire insulation crew to do it after.


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## moey (Feb 4, 2017)

Hard to tell but your basement looks fairly modern have you considered bringing it into a conditioned environment and not insulating the ducts. In that environment the only thing your adding insulation for is to avoid condensation. Its a bit different if you have a duct running outside or in the attic.


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## Fish On (Feb 4, 2017)

moey said:


> Hard to tell but your basement looks fairly modern have you considered bringing it into a conditioned environment and not insulating the ducts. In that environment the only thing your adding insulation for is to avoid condensation. Its a bit different if you have a duct running outside or in the attic.



Totally agree.


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## woodgeek (Feb 5, 2017)

I still think its junk.  AS for the FLIR...did you account for emissivity...which is very low for this material?  I would expect it would block radiant emission (maybe 30% of the heat loss) when new/clean (dust and oxidation will increase the emissivity), and add maybe R-2 for the convection term.

At least thats what independent lab tests show.

http://www.greenbuildingadvisor.com...ectix-still-claiming-r42-its-bubble-wrap-my-h


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## Brian26 (Feb 12, 2017)

Woodgeek- I did see that report. I think it the product itself does have a low r value but if installed properly with an air gap it does seem to work very well and the reported r6 maybe be correct. I believe the advertised r value is really an assembled value, which is kind of misleading. I will add its insanely labor intensive to install this with the air gap having to add 3/4 spacing around the duct. I would guess very few if any hvac contractors would ever take the time to install the air gap. I could probably do my ducts 5 times faster if I didn't have to add the air gap. 

The basement is about 800 sq ft and unfinished with open walls with r-13 fiberglass. We don't use it at all really. Its more utility and about the only time I am ever down there is for laundry or use the workbench. So I could really care less about the temperature down there. I have a thermometer down there and its pretty much stays at 50-55 in the winter even when I am running the stove and the furnace doesn't run. I would rather have the heat/ac going right  up into the living area. I did some further testing as well and I am seeing a 10-12 degree rise on my supply temperature duct sensor. Also, seeing around the same rise on my ducts on my first floor.


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## woodgeek (Feb 12, 2017)

I think you are going from R-0.5 (un-insulated duct, single boundary layer) to about R-2 (reflectix), which is a difference.  

If its free and you like it and want a slightly colder basement, enjoy.

I have seen no evidence that you can get R-6 (current code for new construction in most areas) with reflectix. The FLIR is not quantitative for low-E.  Are the warm stripes in your image tape?  Those might be a better gauge of skin temp (unless they are foil also).


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