I am in the middle of a 1500 sq ft. (plus 900 sq ft of basement) addition to my home. I am having a HVAC guy connect a 5 ton heat pump to my existing system. The new ductwork in the addition is like a work of art but it connects to something that looks like an idiot on drugs threw it together. There are several problems with the existing system:
Large return ducts are connected in the crawl space are the flexible round type. They are maybe 18 to 24 inches in diameter and there are visible places where the ducts are tied together with string and have holes exposed. The ducts are salvageable and in good condition but they are not connected well.
The branch ducts (6in diameter) are loose and not connected well.
Is there a recommended way to connect these ducts? Regular duct tape doesn’t seem good enough. Is there another method of wrapping and sealing these ducts so they stay together?
Thanks,
Doveguy
Replies
Regular "duct tape" isn't intended for ducts. Never was.
Okay, so what is used?
Dove,Duct mastic and fiber tape. Big box or HVAC supply.KK
flex duct is a a poor solution in any case FWIW, but is a terrible idea for a return duct. It collapses too easy as it is, but suction can contribute to deflating it.
Connections are made by slipping flex over a solid at end or solid 'nipple" for longer with joint, then using clamp to cinch it down. Foil tape for seal but not to hold them together mechanically.
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Hey Piff,
Pardon my ignorance, but what is "FWIW"?
Dove
FWIW it means For What It's Worth.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
there is a tape just for flex duct... it's some badddazzzzz stuff... if you tear it with your teeth and it touches your lips it will tear the skin off....
ask me how i know... my HVAC guy didn't believe... so he tried it... now he knows...
p:)
BAHAHAHAA! Ohhhh, I'm sooooo glad I didn't discover that myself! Oh, that must have been miserable.
Tu stultus esRebuilding my home in Cypress, CAAlso a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
Flex duct has an inner plastic tube that has a metal wire looping around to keep it round. Then a middle layer of fiberglass insulation. Then an out layer of plastic or reflective foil.
To properly fasten it, you need two things:
1. Gigantic zip ties - the go from 24" to 36" long and are about 3/8" thick.
2. Flex duct tape, as Ponytl mentioned.
To connect the flex duct to a metal fitting, you would push back the outer jacket and insulation about 6" to reveal the inside tube. You would slip the inner tube over the metal, prefferably over a lip in the metal fitting. You would secure it with the giant zip tie.
You would now take your tape, and use it to creat a seal from the edge of the plastic tube to the metal so nothing slips past the zip tie. With the inside bound and sealed, you can pull up the insulation and jacket again. The jacket is also bound with a giant zip and taped, just in case the inner passage gets punctured it will be less likely to leak.
Bad duct connection sealing is pretty common. Before hiring my HVAC contractor, i made sure I could se an example of their work. I was glad I weeded out the company I was initially going to go with!
Tu stultus es
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
Thanks for the info.
Dove