Hard or Soft?

[Natedizzle]

I'm getting to the ventilation step in my new studio, and am having issues deciding what type of duct work to use.


The sizes are all worked out, but all the hvac guys I talk to say to use soft insulated hose...

I think semi rigid steel hose would be better and more durable...

I've never used a ducted system before so this is new territory, and after reading for days about flow rates I'm going nuts. I also want it to be as strong and permanant as possible. Thanks

Nathan

[brettodie]

use fully rigid. the soft flex lines have a wire that spirals thru them it causes the air in them to spiral also meaning your fan has to work harder to move the air thru the duct and lowers your effiancy.you have no need for insulated duct work at all if your just using it for venting purposes.if you have any questions pm me and ill drop you my digits and we can talk. hope you enjoy your new set up. peace brett

[FLAGSTAFFglass]

Ive always used the bendable insulated duct tubes.....14 inch diameter I think. I like it because it is cheaper than the rest and probably a butt-load easier to install. I would not worry about hurting or puncturing that stuff either. Ive beat the crap outta mine and the worst that has happened was to puncture the outer insulated later.....there is also a separate tube inside the insulated tube that is protected.
However, you did say ideally so maybe throw down for the chauncey stuff......dont know the cost. Good luck post pics with what you decide.
-Cory

[somewhere]

Metal duct carries sound big time very loud. Flex duct reduces air flow dramatically but anyof it works. I like hvac board the yellow fiberglass insulation with aluminum covering one side. You cut the board and there is a special tool for cutting the 45degree angle and fold it into whatever size duct you need. You can mount fans directly onto the duct board. Or use short runs of flex from the fan to the "plenum" duct board duct. You want the fiberglass side to the inside and plenty of aluminum duct tape for the outside corners. This is a fairly cheap solution. We used attic fans mounted into the plenum then one 14" slip joint (metal fitting that can turn in any direction) one 16"to14"bell reducer then one 18"to16" bell reducer. You get the idea, it makes a hood. One thing to keep in mind if your feeding several fans into one plenum your plenum needs to be big enough so it doesn't make back pressure. We had the guy at the hvac place figure what size we needed for our plenum by figuring total cfm's on the fans. If you have a airconditioned shop this will really help take the heat out and away also muffles the sounds of all the fans.

EDIT:
I just reread this and I'm not sure it makes any sense or even applies to one or two torches. I'm off to Jville and I'm already late so it is what it is :spaced:

[slave]

i work in the hvac trade (at least i got my licence for it) now i mostly just do side jobs. however im not a duct guy... when talking to our duct guys though he said that the soft insulated is not meant for the temperatures coming off the top of my bench/torch... and insulating it is worse... though it my reduce sound level it will help retain the heat and abuse your blower... ridge can cut down on airflow just as much it really just depends on the amount of bents in the run. flex is easier to run however i still vote rigid.

[BlueDevil]

Rigid ducting gives the best flow. Thats my opinion as well as the heating/air guuy that built my system. We used an insulated box for the multiple squirel cages, and noise is not a problem... Nathan, let me know what you're building and we'll talk. my 2 hoods have been wonderful and we had 6 stations up at a colab, with just my 2 hoods, and had no issues at all, nobody got torch drunk.
Hope this helps, maybe we can get together sometime.

Lee

[Natedizzle]

thanks guys! I think I'm going with a solid duct.

Now for the second question... The main duct is going to be 14", can I also buy a 16" duct and make my own insulated duct strictly for noise control? is this a bad idea... etc.

Lee- let me know when you're in town... I'm almost always at my house.

Nathan

[BlueDevil]

Nathan, when mounting all ducting add a small rubber pad between the mounting and what your mounting to. This eliminates most noise problems as well as vibrations. With 2 torches running and the vent system, we still can speak to eachother clearly without having to yell or even raise our voice. I'll be in the area Sat and Sun Nathan if ya want to get together. Busy most of the day Sunday though... Gotta watch the Hawks! Give me a shout if ya want.

360-520-5557


Lee

[Natedizzle]

Damn... I'm going to be in Bremerton for the weekend. I'll call you tomorrow


Nathan

[somewhere]

i work in the hvac trade (at least i got my licence for it) now i mostly just do side jobs. however im not a duct guy... when talking to our duct guys though he said that the soft insulated is not meant for the temperatures coming off the top of my bench/torch... and insulating it is worse... though it my reduce sound level it will help retain the heat and abuse your blower... ridge can cut down on airflow just as much it really just depends on the amount of bents in the run. flex is easier to run however i still vote rigid.

I have to disagree the yellow insulated hvac board can take some serious heat. We built hoods over our furnaces and glory holes with the stuff and I know many that use it. As far as heat on the fans go there should be enough air flow to move it away. We run a teaching facility thru the college with 16 benches. Could you imagine what all that would look like if it was ducted individually? Anyway it's more work and there is some math involved so it's not for every shop but if your trying to plumb multiple workstations it is an alternative. Besides you shouldn't run mutiple 14" fans into a 14" duct.Ok I need my morning coffee.
BTW: Our ventilation was inspected and approved by a licened hvac pro.

[slave]

I have to disagree the yellow insulated hvac board can take some serious heat.


like i said im not a duct guy and was only speaking on what our duct guys said. this was in reference to what they were using in a home system coming off the main metal ducting which ataches to the output vents. i do belive we are talking about two different types of soft insulated flexable duct. as im sure there are many i was just noting on the one that i was aware of and asked about... maybe i should research the differnt types and post them. along with temperture ratings.

[brettodie]

two different things guys :) one of ya is talking about flexpipe and the other is talking about metal backed hvac insulation board,cut into duct shapes. id still go with metal myself and i was a duct guy for awhile and my dad did hvac install and design for over 30 yrs and has installed/ designed hundreds of vent systems.id go metal just cause of long term wear and tear and use. in a larger shool situation i would have used home style larger square ducting. in any system you design theres a bit of math involved if you do it the right way. most of the time i just over shoot by enough for my own stuff that i dont have to do all the nit picking math. good luck with your system peace brett

[maui greenstone]

i have set up about 5 ventilation systems and i have to go with the rigid just because of its durability but to be honest i love open air the best. I had a torch setup on my back porch in maui overlooking the mountains and nothing is more inspiring than a beautiful landscape to look at. Beats looking at a wall anyday. but thats beside the point go with rigid