4 inch versus 6 inch hose

[ubfine]

Hello there...brand new to this blog, but have been reading all the posts and almost finished this project. Have not turned it on yet, not quite there. I am using 4 inch diameter dimensions for duct and hose. My question to you folks is (that I may have been lazy), is this going to be OK for performance? Or, should scrap the 4 and go to the 6. I would rather stay with 4" but not at the cost of losing drastic performance. I notice that most have used 6". I have a Delta 50-760, 1.2 HP, 1200 CFM. Thanks for any replies.

[retired2]

Hello there...brand new to this blog, but have been reading all the posts and almost finished this project. Have not turned it on yet, not quite there. I am using 4 inch diameter dimensions for duct and hose. My question to you folks is (that I may have been lazy), is this going to be OK for performance? Or, should scrap the 4 and go to the 6. I would rather stay with 4" but not at the cost of losing drastic performance. I notice that most have used 6". I have a Delta 50-760, 1.2 HP, 1200 CFM. Thanks for any replies.

The best choice is 5" for that DC.

[dmh]

I have a HF 2 HP and just finished a top hat version with a six inch inlet and outlet. I originally built it with the six inch ports just in case in the future I wanted to move up to larger pipe. Playing with it to see how it works I had a four inch outlet going to the DC. On my finale hook up I ran a six inch pipe from the outlet of the separator to the DC. Dropping handfuls of sawdust in the inlet I could see a huge difference between the smaller and larger pipe. There?s allot more speed and air volume using the six inch. With the 4 inch I could watch pieces and dust make the turn down into the drop slot. With the six inch the dust is moving too fast to see it happen.

Needless to say I will be getting rid of what 4 inch pipe I have and working my way to 6 inch.

[Dougp28704]

I have the HF as well.

dmh, how did you connect to the H.F.'s 5" inlet?

[dmh]

I just cut out a 6 inch circle with a 4 7/8 hole in the middle of it out of plywood. I hose clamped the pipe to the ring and the ring to the collector is just a friction fit.

[ubfine]

 :) Thank you for your comments. Sounds like I need to follow your recommendations and go with 6" diameter.
Thanks again.

[Dougp28704]

There are different opinions out there on this. Most say that the HF cannot handle 6? central system.

But I have no idea what is best.

I am finding that the duct work is so expensive. Would be cheaper to have 3 or 4 H.F. collectors. One dedicated to each machine.

[Peter]

Every time I run calcs for a system using the HF impeller, I come up with 5" ? duct being most efficient.

I think the only reason to install 6" ? duct is if you plan on replacing the HF unit with one that has a larger diameter (and more efficient) fan and a more powerful motor. The HF unit just doesn't move enough air to keep the FPMs where you want them.

[dmh]

Is there a simple way to do a real world test on this? (other than spending a couple hundred of dollars on pipe?)

My only experience with this is going from a 4 inch to a 6 inch pipe on the outlet side of the tophat to the DC in wich worked alot better as I dumped saw dust in the inlet.

Here is my setup...

[Dougp28704]

I think you have to either trust the math, or spend the money and see how it works.

On another subject, I just posted a question ?round to rectangular?. What I made last night looks like your inlet. Well, Kind of like it. Mine isnt quite as pretty. Yours is one piece with no cuts, right?

[retired2]

Every time I run calcs for a system using the HF impeller, I come up with 5" ? duct being most efficient.

I think the only reason to install 6" ? duct is if you plan on replacing the HF unit with one that has a larger diameter (and more efficient) fan and a more powerful motor. The HF unit just doesn't move enough air to keep the FPMs where you want them.

Peter, your post should be in 24 pt bold red text and anchored to the top of this thread.  Over and over again, I see people fretting over whether to choose between 4" and 6" pipe, when in fact the best size is 5" for the majority of DC's being used by people on this forum. 

There are certainly situations where 4" or 6" is the correct size, but a lot of people make the mistake of using those sizes when they should be using 5".  And they make this mistake for one of two reasons.

1) They don't want to take the time to learn how to do the calculations.  It is not rocket science,  but you have to be willing to invest a little time.  Along with that goes the mistaken belief that bigger is always better.

2) 5" pipe is not readily available at their local big box store.  Well, I say go to an HVAC supply house.  They sell it just as cheap as the big box stores that do carry it, and it will likely be higher quality.

[dmh]

I think you have to either trust the math, or spend the money and see how it works.

On another subject, I just posted a question ?round to rectangular?. What I made last night looks like your inlet. Well, Kind of like it. Mine isnt quite as pretty. Yours is one piece with no cuts, right?

Yes, it was made from one piece of 6" round pipe. No cuts. Just bent the corners where I wanted them.

[dmh]

Peter, your post should be in 24 pt bold red text and anchored to the top of this thread.  Over and over again, I see people fretting over whether to choose between 4" and 6" pipe, when in fact the best size is 5" for the majority of DC's being used by people on this forum. 

There are certainly situations where 4" or 6" is the correct size, but a lot of people make the mistake of using those sizes when they should be using 5".  And they make this mistake for one of two reasons.

1) They don't want to take the time to learn how to do the calculations.  It is not rocket science,  but you have to be willing to invest a little time.  Along with that goes the mistaken belief that bigger is always better.

2) 5" pipe is not readily available at their local big box store.  Well, I say go to an HVAC supply house.  They sell it just as cheap as the big box stores that do carry it, and it will likely be higher quality.

Where can one find out how to do these calculations?

[Peter]

Where can one find out how to do these calculations?

Use this forum's search function and look for posts by retired2. Recent ones. Like in the last month or so.

[dmh]

Thanks Peter, I searched and read for about an hour and a half this morning and couldn't find anything. Don't know if I scimmed over it or was searching for the wrong terms.

I think I'm done reading. I've read where people say you need 5" and then I've read where people use 6" and that works. So far all I definetly know is that I've got a headache from all the information. :o I would rather go with 6" incase I upgrade to a larger DC in the future. I think I'll just go buy a piece of 6" pipe and an elbo, dump a hand full of dust and shavings in it, and if it sucks it up through the pipe around the corner I'm fine.