DC ductwork

[dale rex]

anyone using metal ductwork that is meant for heating and air conditioning? I often have heard that it not strong enough to withstand the negative air pressure that DC's create. Just curious because I might change the duct size for my Grizzly 2 hp DC from 4" to 5", and dont want to spend the $$ to get REAL DC ductwork, and 5" PVC probably isnt that easy to come by. Although, I heard of people finding 6" PVC at their local home centers occaisionally.

[Jim O'Dell]

Dale, you won't find 5" PVC at all. 1" increments to 4", the 2" increments thereafter. I understand 24 guage is ok. Spiral would be the best way to go with metal. Jim.

[Mike Spanbauer]

Unless you have a VERY serious DC (7+hp + 15"+ impeller) I believe you can't collapse even 30ga, much less 28ga.

I have a 5hp oneida and it pulls 13+" SP (vacuum more or less)... in order to collapse my 26 ga snaplock, I would have to pull around 28" sp, which wouldn't happen in my 6" straight runs (which are the most at risk since elbows are stronger due to ribbing).

This is not based on personal testing, just what i've read in several places...

my 2 cents :)

mike

[Mike Sheppard]

Dale
The stuff that is called "warm air" is 30ga and would not be strong enough, however 26 or 24ga (used as smoke pipe) would work for you. The rub comes with the adj. fittings, the 90s and 45s are very tight radius, the center line radius should be 1 1/2 times the pipe size. That said you could get by if you use very few of them, and use laterals not tees, keep flex as short as possable. It does come in 5".
Mike

[Kent Fitzgerald]

I used 26 ga HVAC snaplock pipe, whcih is readily available, and 26 ga "economy" fittings from Penn State Industries.

[dale rex]

hey Kent, where in the Lehigh Valley are you from? Do the fittings from Penn State fit the HVAC pipe?

[J.R. Rutter]

You can use double adjustable elbows to get a long radius. Caulk all seams once it is in position. I used the 28 ga. snap lock in my garage system with a 2 HP cyclone. When I upgraded to a 10 HP blower that someone gave me, I sucked the whole system flat.

Spiral pipe is not much more expensive if you can find a local manufacturer. Call a couple of HVAC contractors to see where they buy.

[Jack Hogoboom]

I bought my ducting at HD. Five years and going strong. My super dust Gorilla is hooked up to it and it shows no signs of stress whatsoever.

Jack

[Rick Potter]

On my previous shop system I used HVAC from HD, with a 1 1/2HP Onieda cyclone. I left the 2 1/2" hose going to the blade guard on my RAS open all the time...no gate. This way the system always had a bit of flow.

Worked fine, plan on the same strategy (but larger) when I finally hook up the new shop.

Rick Potter

[john tomljenovic]

2hp dust gorilla with 26ga snaplock and a mixture of standard fittings and some onieda custom/long radius fittings. the system is working fine.

[Kent Fitzgerald]

hey Kent, where in the Lehigh Valley are you from? Do the fittings from Penn State fit the HVAC pipe?
Hi, Dale

I live in Emmaus, work in A-town, and had to look up Emerald on a map :D.

Yup, the 5" fittings and pipe all fit.

[Bill Arnold]

Dale,

I'm using the 26ga duct and wyes from Oneida for my main runs, then 30ga from the borg for my drops. So far, I've seen no issue using the smaller diameter (5" and 4") for drops and final connections. I'd be concerned about using larger diameter 30ga, though.

On the wyes, I haven't found a local supplier with "backward" wyes or uncrimped wyes that can be used for dust collection. All I've seen here is the HVAC "forward" air flow versions.

[dale rex]

Bill, is there a difference between the backwards one and the forwards one? I havent looked at Home Depot for any of it yet, but when I go to look at it ill have to pay special attention to this.

[Jim Becker]

Dale, you want wyes that are designed for DC or modified for correct flow. Crimps in the wrong direction can snag material or clog. BTW, 26 gage snap lock is pretty easy to find... Even HD carries it. (silver label on boxes)

[Clay Crocker]

Dale,

In my last workshop I ran all 30ga snap lock duct because that was all that my local home centers carry (We don't have a Home Depot in Springfield.....yet). It worked fine on a 1-1/2 HPDC with a 6" main and 4" drops. That 30ga 6" would flex from time to time but I don't think my old DC could come close to collapsing it. In my new shop I upgraded to a 2HP cyclone and I went with 26ga snap lock that I ordered from McMaster-Carr. I got all of my fittings from Oneida and the blast gates from LeeValley. Based on my experience, if you have a 2HP DC you can not go wrong with 26 ga snap lock duct.

Clay

[Tom Leasure]

Dale,
Am useing 6" 30ga. snap lock pipe on a Grizzly 3hp DC. It works great. I did seal all the seams & joints with a metal duct tape to prevent a leaking. It should be avab. at a local heating a/c outlet.

[William Belknap]

Dale,
I had to reinforce a 3' section of 9" diameter 26 GA HVAC when connected between a 5 HP driven 14" impeller and a Clear Vue cyclone (Ed Morgano's CV1400). Two 9x36 pieces of 1/8" plywood with a lengthwise cut halfway through each to allow them to be placed like egg crating did the trick. The 26 GA elbows have been plenty strong.
Bill

[Michael Sapper]

I used 26 ga HVAC snaplock pipe I purchased at HD for about $4 per 2 foot section, and various 26 ga economy fittings from Penn State Industries. This combo is pretty cheap and works great

[Rod Sheridan]

I have used 30 gauge snaplock ducting for both a 1.5 HP and a 2 HP Oneida Cyclone with excellent results.

I made my pipe hangers from 12mm plywood, with a hole in them the same size as the duct. This keeps the pipe round in shape, which increases its crush resistance.

I haven't had any problems in 4 years of use with the 30 gauge snaplock pipe. I sealed all the seams and joints with foil tape or silicone sealer, depending upon the location.

Regards, Rod.

[Keith Beck]

When I upgraded to a 10 HP blower that someone gave me, I sucked the whole system flat.


Man, that had to be cool! I'd like to watch that! :D

[Quesne Ouaques]

Dale, you want wyes that are designed for DC or modified for correct flow. Crimps in the wrong direction can snag material or clog. BTW, 26 gage snap lock is pretty easy to find... Even HD carries it. (silver label on boxes)

Jim:

I have been asking around at the Home Depots in the area, and no one can tell me if the snap-lock they carry is 26 gauge. I haven't been able to find any snap-lock in the box, much less with a silver label!

Are you using the HD 26 gauge? If so, could you take a look on your installed hardware for a laser-scan label and post the SKU number from a 5 foot length?

Or perhaps just point me to a HD location that you know carries it. I'm in the Bala Cynwyd area, just outside Philadelphia.

Thanks very much!

[Quesne Ouaques]

Dale:

I've been designing and setting up my 1 1/2 hp DC system over the past few months (things move slowly 'round here :-) I called and/or looked at every HD in my area, and none of them carried the 26 gauge snaplock. It was all the 28 or 30 gauge.

Thanks to a helpful creeker, however, I did find a very economical source for the 26 gauge snaplock at an HVAC supplier called R. E. Michel. They sell wholesale to contractors (which I am not), and to be truthful they were neither friendly nor pleasant when I asked for them to sell to the lowly public. They refused rather rudely. So I called a buddy of mine who does some contracting work, and he bought it for me. 10 pieces of 6" diameter 26 gauge for $8.00 per piece. That's about 30% less than the least expensive internet woodworking source! And no shipping!

All the rest of the 26 gauge fittings I bought from Penn State Industries. I've installed more than half of it and, even before doing the final leak-seal step, it passed my "acid test" with flying colors. I put my 13" Delta planer at the end of a 18' run of 6" pipe (plus a 2' drop and 4' of hose), and the DC pulls hard enough to easily keep the planer cleared of chips! Of course, when the system is done, my planer will be parked much closer to the DC, but I just wanted to see what the system was capable of. I had high hopes, but I never thought it would be that good from a 1 1/2 hp !

After reading Sandor's book on Woodshop Dust Control, it seemed best to go with the 6" pipe. It reduces static pressure on the long runs but still maintains adequate velocity. Of course this is all with only one gate open, but that's all I'll ever want or need.

[Jim Becker]

Quesne, The RE Michaels on Rt 611 in Warrington sold to me with no problems...even took my AMEX card. More than once, even. But that was awhile ago. Perhaps they are clamping down a little...

[keith ouellette]

If you do decide on 6" pvc Call a few plumbing supply stores and ask them for the cheapest 6" they have. It will be cheaper than HD if you find a reasonable store willing to help.

[Quesne Ouaques]

Quesne, The RE Michaels on Rt 611 in Warrington sold to me with no problems...even took my AMEX card. More than once, even. But that was awhile ago. Perhaps they are clamping down a little...

Hi Jim:

Thanks. When I looked and called around, there were several R.E. Michel managers who seemed very nice and did not care much about whether or not I was a contractor. The only one close to me that had any of the 6" 26 gauge in stock, however, was the one in Upper Darby (just west of Philly).

I called ahead to make sure they had it in stock and to make sure I could buy it even if I had no account with them. The guy said that it was no problem. He could put it on a house account and even take a credit card.

I went in the next day and asked for 10 pieces. The guy behind the counter (skinhead type in his early 20s) looked at my normal (i.e. clean and unstained) street clothes and asked in a sarcastic voice, "Who's it for?". I told him it was for me and that I had called the day before. He said, "Are you a contractor?" Looking puzzled, I said no. Then he said (with an sort of arrogant nastiness in his voice), "Well we can't help you. We only sell to contractors."

I asked to speak with the manager and he just pointed to a sign which read "We only sell to contractors." From that moment on he went back to talking to his buddies in the store (contractors, I presume) and pretty much ignored me. I walked out very pissed off.

It broke my heart to call my friend and have him buy it for me. I was loath to give the place a dime of my money after being treated that way, but I had the whole day planned to start installation and I did not want to waste a whole day driving around to get it somewhere else.

I didn't really have anyone to complain to since the sign was clearly posted, but I can't say they put much emphasis on customer service. The guy was a royal prick! (pardon my French). FYI - I did not take this as a reflection on R.E. Michel in general. Just a bit of bad luck on my part that the guy who was working that day in that store was acting like a jackass.

Anyway, it's all ancient history now. My DC is up and running!