Duct Work

[Steve Doerr]

I'm in the process of replacing my 4" PVC piping with 7" and 6" metal duct work for my dust collection system. I have a couple of questions for those of you that have installed the metal piping.
1. My long run piping is the snap lock style. Once it is snapped together, do I need to seal the long seam with either caulk or duct tape?
2. Do I need to use caulk and duct tape to seal all of the joints or will the duct tape do the job?

Thanks for you help.
Steve

[Greg McClurg]

Hi Steve,

Personally I think you would be happier in the long run to tape the joints. I used the metal duct tape and it works great. I will say that my piping is not the snap together kind so that could make a difference.

[Wade Lippman]

I didn't tape the seams and used just duct tape on joints. Seems fine to me.

[John King]

Why replace the PVC with metal? Remember that it's the velocity of air in the duct that moves sawdust/chips. Unless you upgrade the dust collector (increased cfm of air) simultaneously with increasing duct size, you will notice a dramatic decrease in performance. - John

[Ole Anderson]

I used foil tape on the long seams and on the joints. I used general purpose clear silicone on the bends and wyes, doing it again I would use aluminum color silicone available from a HVAC supply shop on the bends and wyes. It worked great to touch up joints when I just replaced my furnace with a 96.5% efficient model. Regular "duct or duck" tape has a limited life compared to foil tape. Do it right the first time. And use foil tape designed for metal ducts, not the reinforced foil tape designed for insulated flex duct.

[Steve Doerr]

Thanks guys.

John--I upgraded my dust collector a year ago to the Oneida V-3000, but kept my old 4" PVC duct work. So this year I decided to go and upgrade to the 7" & 6" metal duct work. By working with Oneida I made sure that everything matched and that I would have the suction necessary for all of my machines. Hope they got it right:eek:

Ole--thanks for the feedback on the silicone and on the seams. I hadn't thought about sealing the flexible elbows. All of my wyes have been soldered/welded at the joints. When I used the term duct tape, I was referring to the foil tape.

[James Gunning]

Steve,

You will see a dramatic increase in the amount of air flowing through your system and as a result much better dust and chip pickup. Four inch pipe just isn't large enough to flow the amount of air that a cyclone system like the V-3000 produces. Good choice.

[Jim Finn]

I am a retired sheet metal worker and I have installed, literally, miles of duct. I installed a six inch snap lock system in my woodshop and I used a brush on sealer on all the seams including the snap lock seams. I used the product that is used to coat the top of mobile homes for this. Two coats. Silicone caulk will also work well. Regular duct tape will fail over time but the foil tape is much better for this.

[Ben Rivel]

Got a V-3000 myself and all metal ducting. I just used tape on the straight runs of snap lock. Three screws for all joints then tape around the joint seam and I used silicone caulking on all pre welded wyes to ensure air tight sealing as well as all around the blastgates. Not a leak that could find and I have 8 blastgates.

[Kevin Jenness]

A bead of silicone around the joints after assembly is far easier to undo than one in the joints- I learned the hard way.

Self-drilling hex head screws are the easiest fasteners I have used.

Self-cleaning blast gates are a good upgrade- regular ones tend to get loaded and impossible to shut completely and are difficult to disassemble for cleaning.

[Jim Becker]

I do/did fully seal all joints including the lengthwise joints on snap-lock. That said...do NOT use "duct tape". It's not really for ducts. ;) You want foil tape designed for HVAC work to do this job. Seals better and longer and adds a bit of rigidity, too.

[Ole Anderson]

Screws can catch shavings, if you do use them, put them at the 4, 8 and 12:00 position. I removed mine and replaced them with 1/8" x 1/8" pop rivets. Screws work well for temporary assembly or HVAC work. Just remove the screw, drill out to 1/8" and insert pop rivet (before you tape the joints).

[Steve Doerr]

Thanks everyone. I wanted to get some info on assembly before I started putting it together. Now that I am putting it together I better understand the comments about the silicone around the blast gates and the wye joints. I also liked the idea about the screws to hold the joints together. Got the old PVC duct work down and couldn't believe all the dust that had accumulated on the pipes and around where where all the joints were. I'm hoping (and my wife too) that I will see a BIG difference once I get this all put together.

[Steve Doerr]

Good point Ole. Thanks for the heads up.

[Jim Finn]

Screws can catch shavings, if you do use them, put them at the 4, 8 and 12:00 position. I removed mine and replaced them with 1/8" x 1/8" pop rivets. Screws work well for temporary assembly or HVAC work. Just remove the screw, drill out to 1/8" and insert pop rivet (before you tape the joints).


This is what I did also.

[Dave Haughs]

I'll echo what others are saying. I used foil tape and the brush on duct sealant paste stuff. Not both together but in combinations. I found I liked brushing the sealant on vs tape when I could get away with it. But I have tape in many places too.

[Ben Rivel]

I would have liked to have used pop rivets instead of sheet metal screws, but seeing as how I have taken apart my system to make changes quite a few times already Im kind glad I didnt as the screws are much easier to remove than the rivets would have been.

[Chris Barrett]

I'm using screws just to keep pieces in place as I put together the ducting ( still a work in progress) and then I pull the screws out and do the whole joint and long seam with foil tape.