which type 'Trunk duct'

[NYB77]

I am in the process of getting estimates for central a/c (no heat) in my ranch home. I did a manual J and came up with 2 1/2 tons and so far both contractors came up with the same number. One contractors estimate says "trunk duct to be galvanized steel wrapped with vapor barrier insulation."
The other contractor uses a pre-insulated (insulated on the inside) plenum which he claims is R-9. What are your thoughts on this pre-insulted duct?

The reason I ask is because a friend has told me to avoid the plenum with the insulation on the inside because "it eventually dries out and blows around your house". The installer says that may have been the case with the early stuff but not the one that he installs. He is willing to do the same type as the first contractor and even mentioned an exterior 'bubble wrap' that is higher R valued but would cost a few dollars more.

What are your thoughts?

[seatonheating]

I am in the process of getting estimates for central a/c (no heat) in my ranch home. I did a manual J and came up with 2 1/2 tons and so far both contractors came up with the same number. One contractors estimate says "trunk duct to be galvanized steel wrapped with vapor barrier insulation."
The other contractor uses a pre-insulated (insulated on the inside) plenum which he claims is R-9. What are your thoughts on this pre-insulted duct?

The reason I ask is because a friend has told me to avoid the plenum with the insulation on the inside because "it eventually dries out and blows around your house". The installer says that may have been the case with the early stuff but not the one that he installs. He is willing to do the same type as the first contractor and even mentioned an exterior 'bubble wrap' that is higher R valued but would cost a few dollars more.

What are your thoughts?


A thoroughly sealed metal duct with outside wrap is definitely the way to go in my opinion. Why not take the variable of insulation ever being a problem in the airstream and do it this way?

You don't need more than R8 which is pretty standard.

[lancerbomb08]

agreed^^^ i always just hated being the one wrapping it haha

[skippedover]

I agree with the other posts. Shiney metal with R-8 foil backed insulation. I'd stay away from bubble wrap, not because the product is no good but because it's most often installed improperly. To get the R-value it needs sto be installed with stand-offs of 1/2 inch from the trunk. If you want a higher R-value, more spacers, more insulation. Most installers never bother with the spacers and put the wrap in direct contact with the duct, giving an R value only slightly better than the bare metal trunk. I too would stay away from the internally insulated plenum. We do internal insulation only when sound is of exterme importance, like a sound studio. Otherwise it's always metal duct, foil backed R-8. 'Nuff said.

[Stamas]

I'm betting the "internally insulated" trunk is Ductboard.

[bigtime]

Ductboard or lined sheetmetal duct will be quieter.

[NYB77]

Bigtime:
It may be quieter but what do you think of its durability and does it degrade over time? I have to find out if it is 'ductboard' or lined sheetmetal. I'll probably avoid the 'ductboard' because it sounds less durable. Even though I like that contractor a bit better I may insist on the R-8 insulated metal duct.

[seatonheating]

Bigtime:
It may be quieter but what do you think of its durability and does it degrade over time? I have to find out if it is 'ductboard' or lined sheetmetal. I'll probably avoid the 'ductboard' because it sounds less durable. Even though I like that contractor a bit better I may insist on the R-8 insulated metal duct.


If the air velocities are kept under Manual D's maximum guidelines then metal is more than fine!!

I would rather quiet duct close to registers with flex, at least there is no insulation in contact with the air.

[NYB77]

Thanks guys....I have selected the 2nd contractor and he is going to install the metal trunk duct wrapped with R-8 foil wrapped insulation. Everything else is similar (one was installing Tempstar while the other was installing Comfortmaker which are both ICP products). I'm pretty happy with the price and details and I'm glad that I did my research here.

PS: Is there any hierarchy in the ICP product line?

[jeepsterman]

Thanks guys....I have selected the 2nd contractor and he is going to install the metal trunk duct wrapped with R-8 foil wrapped insulation. Everything else is similar (one was installing Tempstar while the other was installing Comfortmaker which are both ICP products). I'm pretty happy with the price and details and I'm glad that I did my research here.

PS: Is there any hierarchy in the ICP product line?

Icp is owned by the Carrier Corp and they come out of the same assembly plant in Indianapolis, IN

[skippedover]

Icp is owned by the Carrier Corp and they come out of the same assembly plant in Indianapolis, IN

That is true but to totally different specifications. Don't be misled by the claim that one company builds all the products the same. It's true that Trane and American Standard, Carrier and Bryant are spitting images of each other, built to the same standard just with different brand stickers on them. But that's where it ends. Payne is a good product but not as good and the mainline. I think it's a little bit of a disservice to claim that something is built at the same plant. Just because it's built there, doesn't mean that it's built to the same tolerances, that the same thickness of sheet metal is used or that the same construction techniques are even used. That's why there's different pricing. It isn't just the advertising, they have to economize somewhere to get the lower prices. But don't misinterpret that to mean the products are junk just because they don't carry the mainline stickers. On the contrary, it's the installing company that makes all the difference. Get the right company, they can make a string of beer cans cool properly. Get the wrong company and a gold plated Carrier could operate any worse. It's all in the hands of the installing company. Do your homework and you'll be okay. Or, you can always GAMBLE!!