Duct installation help????? - Contractor Talk - Professional Construction and Remodeling Forum

Remco Air · 08-09-2009, 06:26 PM

Thanks in advance for any advice given, I am now getting myself into more of the commercial side of things, I have a project that involves me installing exposed spiral duct in an dept. store. I have 20 ft. ceilings, according to the plans the ductwork must be "installed tightly to the ceiling structure," what is adequate for the height to be from floor to the diffuser on the spiral duct? Thanks everyone.

jkfox624 · 08-09-2009, 09:33 PM

Could be wrong but this sounds like a question you need to be asking your sales rep for whatever product your using and then consulting with whoever is in charge on the dept store end to make sure it falls within their specs.

ScipioAfricanus · 08-09-2009, 10:11 PM

Quote:

"installed tightly to the ceiling structure,"

Well that is a pretty vague specification to say the least. Sounds like the architect didn't want to bother himself with finding out how this is done and talking to some HVAC guys. I've run into that before.
Sounds like the top of the duct is supposed be in contact with the trusses but most duct like this is necked down in size as it gets farther from the air handler so that can't be right.
If it has to be rigid I would say use all-thread to hang from trusses and uni-strut on the underside with 20 ga. strapping to go over the top.
Don't know if this is the look they want though but it will not sway this way.
There are other ways to so this to get "the look" though.

Andy.

NickTech · 08-11-2009, 11:53 AM

what type of terminal unit are you using? rectangular take offs with the register right on the spiral, or a branch line coming off with a diffuser box to a register? to hastily interpert the spec. if your using branch lines then technically the bottom of the register would be no lower than the bottom of the main spiral. right?

Remco Air · 08-11-2009, 11:57 PM

Hey everyone Thanks for your responses, Nicktech to answer your question, the plans show rectangular takeoffs from main spiral, rect. branch box to register w/ dampner in between. My main concern is that the air handlers are strapped high to the ceiling,all ductwork will be exposed & painted which brings me to another question someone mentioned to me that I needed to install paint lock spiral, never heard of such, any input? But besides that I have plumbing lines & electrical runs as obstacles not to mention a 17 foot sign, owner wants the duct as high as possible.So my question is what is standard for such an application, I'll try to post a pic. if possible.

NickTech · 08-12-2009, 11:24 AM

well the "standard" would be what the customer wants. i'm not sure what code is for CAli, but if there is no height code then as hi as the ceiling would accomadate the customer. if the branchs are perpendicular to the trunk, then the diffuser box should have the the branch connector off the side instead of the top to eliminate an elbow down adding distance away from ceiling. if its going to be exposed then why not rectangular 45 deg take offs with registers on the take off?
paint has a hard time bonding or sticking to the zinc of galvanized sheetmetal. usually if one is to paint it it would require treatment. but now there is duct available pretreated for receiving a coat of paint. here a link.
http://www.herculesindustries.com/pr....asp?txtid=470

ScipioAfricanus · 08-12-2009, 11:42 AM

I too would say there is no "standard", you could suspend a single all-thread from the ceiling then wrap a strap around the pipe, all kinds of things. Does the customer want to see as little in way of attachments or does he care or maybe he wants to see the attachment to give the "industrial" look.
BTW you can cut etch the galvy pipe with a light muriatic acid solution then prime and paint, this had always work well for us.

Andy.