# Can someone help sort out my duct dilemma?



## steetyj (11 mo ago)

Hey all - brand new here.

I have a Shop Fox W1666 dust collector that I am using as the heart of my DC system in my garage shop - hobby only - 1 tool at a time.

The DC specs:

2HP - 220v
12" impeller
6" inlet/outlet

I am adding a Super Dust Deputy (5" inlet, 6" outlet) and a wynn filter

Given that my cyclone has a 5" inlet, I am running into a bit of a dilemma of course.

I need to do a very short run to the middle of my shop so I can switch the hose b/w table saw and other tools. I am thinking of the following options:

1. ~20 foot run of 5" flex hose direct from SDD to single tool at a time
2 4" PVC duct from SDD to a single drop at middle of shop about 10ft horizontal into a 90 and 3-4 more feet down to tool level. Short run of flex to tools from there.
3. Bite the bullet on some sort of metal 5" duct in the same configuration as #2
4. Ditch the SDD and upgrade to the SDD XL and run 6" PVC duct

#3/4 will certainly cost the most so I guess I'm trying to explore cheaper options as an alternative. Open to any suggestions


----------



## brtech (May 26, 2010)

I think option 1 is the best. You might use the kind of flex that stretches. The next is 2, although make sure your 90 is wide sweep or do it with two 45s and a few feet of straight pipe. I don't think 3 is worth the cost, see below on safety. 4 is just a bad idea, not enough CFM to begin with. I am Not an Expert.

I suspect all 4" will work as well, if not better than 6". It might even do better than 5", although I suspect 5" metal would indeed outperform 4" flex.

You have an underpowered DC to begin with, and you are adding a separator, which lowers performance. You match the duct to the airflow not the pipe size.

You will of course need to use a respirator to be safe: That 2HP rating is suspect (although probably more honest than the HF rating), and 2HP isn't enough to get the fines even with optimal ducting.


----------



## PlentyFarmLLC (Aug 25, 2020)

Do you need the separator? In a hobby shop unless you are running the planer and jointer for hours you're not going to fill that many bags. Might just try your setup without the SDD. If dumping the bags is that much of a PIA add it later. And without the SDD you can just roll it closer to the machine.


----------



## steetyj (11 mo ago)

I guess my idea with the SDD was to keep the filter cleaner and performing closer to max as long as possible.

For space saving purposed I wanted to mount the DC high on the wall and tuck the SDD/barrel in the corner underneath.

If the consensus is that 2HP/12" impeller is borderline to see benefits of 5" metal duct - maybe the question boils down to:

What is better? 20 feet of 4" PVC OR 20 feet of 5" flex? Or some combination thereof?


----------



## PlentyFarmLLC (Aug 25, 2020)

SDD collects the chips and big stuff. Fines get to the filter with or without SDD. SDD is easier to dump.


----------



## gbarnas (Sep 25, 2021)

From personal experience using a stock HF blower, SDD, and Farr-style nano-fiber filter - I used 4" pvc duct around 2 walls to the table saw/router table, Miter saw station, and a multi-purpose workstation. The SDD emptied into a 30-gallon plastic drum. The HF blower has a 5" inlet, so there was a 6-5" reducer on the SDD, which would not be in your setup.

I used that configuration for 3 years, regularly emptied the drum before full capacity (overfilling will push crap into the filter!), and dumped 5 drum loads in that time. When I disassembled everything last summer, I cleaned the filter for the first time by wrapping a clear trash bag around the base and whacking the cage and blowing with compressed air. I was unable to get more than a cup of fine dust out of the filter. There was no regular sawdust or chips in the filter. For me, the SDD did an acceptable job of capturing most of the fine dust and all of the chips and larger dust particles.

My concern would be stepping down from 6" on the blower to 4" duct into the cyclone in such a short distance. I can't imagine that 5" steel would be that much more expensive for a single straight run, but a simple test would be to connect a 10' section of 4" PVC and two 5' sections of 5" steel pipe and compare the results between option 2 and 3.

My new DC uses a blower with a 7" inlet, reduced to the 6" SDD XL, with about 15' of 6" mains, 5" drops, and 4" tool ports with gates close to the port and just a few inches of flex to isolate any vibration from the ducts. I just ordered a pair of 9E300NANO MERV-15 filters from Wynn. I prefer the simplicity of the slide-in filter flange - easy to slide out, clean, slide in and run.


----------



## JohnDon (Mar 14, 2015)

One more suggestion- a variation on option #2: get a 5" to 6" adapter, and have a horizontal run of 6" PVC, with a 4" PVC drop to your tool take-off. I've always wondered why Oneida decided to make the inlet 5", but a short length reduction (from 6" to 5") will result in better performance than a run of 4" to 5". You need more airspeed to move dust up a vertical run, so a 4" drop to your flex would be better. With a drop to the SDD (going with gravity), you can stick with 6".


----------



## steetyj (11 mo ago)

That's an interesting suggestion John. I'd need to do about 8-10 horizontal run of 6"

Is there any concern going from the SDD 5" immediately to a 6" pipe?


----------



## brtech (May 26, 2010)

Read Pentz. It's bad to use a pipe bigger than the system can actually support. Using a 6" duct with a 2HP blower is likely to be a case of that.


----------



## steetyj (11 mo ago)

Yes I tend to agree 6" is going to be too large most likely.

The 4" pvc vs 5" metal still has me scratching my head.

I wonder what would be ideal if cost was no concern?


----------



## brtech (May 26, 2010)

With the SDD, I'll bet 4". The SDD significantly reduces airflow on a system that small. It does a good job of separating. If you measure CFM at the tool, with the real duct, you can see what happens, but that means trying both which is not feasible. There are so many unknowns here that even trying to calculate it would be hard. I've heard of someone trying a relatively short duct on an HF with the Wynn upgrade (but not the impeller upgrade), and there was roughly no difference between 4" and 5". But I think the ShopFox has a bigger motor so that may not apply here.


----------



## steetyj (11 mo ago)

The shop Fox has a 12" impeller and I assume a "real" 2HP running on 240v so I'm hoping for a bit better result than the HF setups

4" PVC is definitely the easiest so I may go that route


----------



## Lazyman (Aug 8, 2014)

Somewhere on LJ someone posted a thread saying that their research indicated that 5" is the sweat spot for the typical 2hp DC. I think that it might have been looking for recommendations on 5" fittings and pipe?

EDIT: This is the thread I was thinking of.


----------



## JohnDon (Mar 14, 2015)

> Read Pentz. It s bad to use a pipe bigger than the system can actually support. Using a 6" duct with a 2HP blower is likely to be a case of that.
> 
> - brtech


I agree with reading Bill Pentz's site, but respectfully diagree with the second sentence. The dilemma is that larger ducts will reduce resistance to airflow, allowing better airflow (CFM). However, for a given CFM the airspeed (FPM) is lower in larger ducts, so there will be less movement of dust particles. If you follow Pentz's math, you need an airspeed of 3000 FPM on a horizontal run to prevent particle hang up. Doing the math for a 6" duct (~0.2 sq.ft cross-sectional area) you need about 600 CFM airflow for adequate dust movement. Even with reduced efficiencies due to the SDD, and bends and transitions in the system, and probably somewhat inflated specs of 1500 CFM, your Shop Fox- and most actual (240 V) "2 Hp" collectors- can handle 6" horizontal runs.

As transition from 6" PVC to your SDD, a tapered transition would be best. In any case, even with a transition, you'll get overall better performance with a 6" run. It's analogous to using a bunch of extension cords strung together- the voltage drop will be less if you can use mostly 12 gauge cords (6" duct), and minimize the lengths of 18 gauge (4", and even 5" ducts).

From a real life stand, with my old Jet 1200 CFM 2 hp DC, I have no problem with dust flow with running about 20 feet of 6" horizontal run and 4" vertical drops to tools.


----------



## wapakfred (Jul 29, 2011)

> The shop Fox has a 12" impeller and I assume a "real" 2HP running on 240v so I'm hoping for a bit better result than the HF setups
> 
> - steetyj


I'm certain you can bet that is correct. You're quite a bit ahead with the SF.


----------



## brtech (May 26, 2010)

Yeah, it's gonna be better, but I think that with the SDD, you lose enough that 5" won't get you anything. If it did, I think it would be small enough that the cost difference would make it prohibitive.

I did a real quick look to see what the difference between rigid and flex is.

https://www.mmmfg.com/wp-content/themes/va/pdf/060601_CC-KW_DuctTechPaper.pdf

is interesting. It shows that when stretched out, there is really not a lot of difference, but when compressed it's more. That seems to say, to me, that Option 1 really is probably the best, as long as your nearest tool isn't right on top of the DC.


----------



## ibewjon (Oct 2, 2010)

My DC system is piped with 5" steel duct, 26 guage. It works great with my 2 HP jet . As stated, there is an article in Wood magazine a couple years back the stated that 5" is the " sweet spot" for this size DC. I am extremely pleased with the results.. Flex duct greatly decreased air flow, keep it to a minimum. And the steel is about the same cost as pvc, and easy to work with. Lightweight and easy to hang. And a plus is that pvc can develop a static charge, and steel won't do that, so no shocks.


----------

