Duct work

[Jking24]

so getting ready to finish up the ac in my 40x60 the unit is mounted on top of a 15' mezzanine at the back wall leaving roughly 45' from the unit to the other end of the garage the plan is to run one main trunk line down the back wall that drops in size periodically to maintain airspeed. And possibly add some branch runs later if necessary. All supply ductwork will be in the conditioned space. What is the most cost effective/ practical install ducting material ? The pre bent square stuff? Or spiral duct. I do have a 8 foot brake so i could bend something up myself but it would just be overlapped and screwed at the seems. I know this has probably been touched on before but i couldn't pick the right wording for search to bring up anything that looked like it covered my question. Thanks in advance

 

[NUTTSGT]

My neighbor is an old school HVAC/plumbing guy. He swears that round metal is the most efficient followed by square/rectangle metal. His theory is the round allows the air to roll through while the square makes the air tumble.

He doesn't like the round flexible stuff as he says the corrugations create restrictions. He believes it gets used because its cheaper and easier, taking basically no skill to install. Granted, he said he knows it has a place for use at times.


Listening to him and thinking outside the box, I tend to understand where he's coming from.

 

[danski0224]

He doesn't like the round flexible stuff as he says the corrugations create restrictions. He believes it gets used because its cheaper and easier, taking basically no skill to install. Granted, he said he knows it has a place for use at times.

Flex duct can be sized properly to overcome the restrictions.

Flex duct is the ductwork and it is insulated and it is sealed if installed properly. Big advantage over installing and then insulating and sealing round or square metal.

Flex duct comes in several different grades.

It can be a good product, but it allows for too much abuse and improper installation.

 

[brewchief]

Round is the most efficient by a slight margin but square or rectangle is fine as well.

Spiral may or may not be readily available and getting a relatively small amount of 10' long duct shipped may not be cost effective.

I've done some jobs like yours with spiral duct and it's pretty nice, looks much better in my opinion then rectangular.

If you are planning on running duct and simply cutting registers into it pay close attention to the registers you use, a standard residential one will yield lackluster results, for spiral duct I use a Hart and Cooley USVH, size depending on duct size and airflow requirements.

Sent from my SM-G965U using Tapatalk

 

[SGKent]

https://www.buildingincalifornia.com/wp-content/uploads/2014/03/duct-sizing-chart.pdf