1 inch return line

[CoryDude]

Just curious to see if anyone has first hand experiences with switching from 3/4 inch to 1 inch pump return lines. I'm rebooting my tank and current have 3/4 inch lines from my mag12 to the dt. But the new chiller I bought had 1" outlets and so I was thinking of upsizing.

just wondering if I'll see a large increase in gallons per hour if I redo all my return lines and use 1 inch piping.

[FireWater]

Not sure, Cory.

I would believe that a larger diameter would lead to less back pressure on the pump though. I can't figure out the math on a 1/4" increase in diameter.

[Dean]

Increasing the volume of water in your return line could have a negative effect on the pump if it is not sized for a 1" return and how ever many feet of head. If the outlet on your pump is 1" and the specs give you flow rated with a 1" return then it would likely benefit. If not then you could actually slow it down with a larger return by creating more head pressure.

I looked up the mag 12. 1200 gph and 3/4 inlet / 3/4 outlet. My professional opinion would be that you will lose flow due to increased head if you go to a 1" return. The chiller has a 1" outlet so that installation would not be limited to a 3/4" return which is probably the average size for return lines.

Anyway. Just my .02 cents. Hope it helps.

- Dean

[alton]

Remember if you are using barbed fitting they reduce your 1" to 3/4"

[Bill S]

Dean,

I don't think hydrostatic pressure works that way. For instance, it doesn't matter whether Canyon Lake Dam has 1 foot of water 100 feet deep behind it, or 10,000 acres of water 100 feet deep behind it - water doesn't compress, so the hydrostatic pressure (head pressure) is the same.

Math tells you that 1" will support almost twice the flow as 3/4". That being said, where ever there is a restriction, it will slow it down. But my motto is: Bigger is better.

[kkiel02]

Cory is your tank drilled for 1"return? Trying to figure out your system.

[CoryDude]

Remember if you are using barbed fitting they reduce your 1" to 3/4"
No flexible tubing for me Alton. I'm going with rigid PVC on the drains and the return.

Thanks John, Dean, Kevin, and Bill. It's been a while since I've calculated flow density using bernoulli's equation, but a larger diameter should lead to less pressure. But dean is right that the 3/4 inch outlet on the mag would limit the flow.

But my eventual plan is to go back to an external iwaki which has a 1" outlet. Kevin, the tank has dual overflows with 3/4 inch returns. I'm leaning to sticking with the current 3/4 lines based on y'all's feedback and then upgrade to 1" lines when I buy the new iwaki later this year.

[kkiel02]

So you are thinking about going 1" from the iwaki you buy to the chiller then y'ing it into two 3/4" correct?

[CoryDude]

So you are thinking about going 1" from the iwaki you buy to the chiller then y'ing it into two 3/4" correct?

Yeppers

[kkiel02]

I think that would work. As you probably know just try and not use 90 degree elbows unless you have to. I like the flex tubing so you won't have that problem. Your sharpest bend will be your bottle neck.

[mkengr45]

Increasing the volume of water in your return line could have a negative effect on the pump if it is not sized for a 1" return and how ever many feet of head. If the outlet on your pump is 1" and the specs give you flow rated with a 1" return then it would likely benefit. If not then you could actually slow it down with a larger return by creating more head pressure.

I looked up the mag 12. 1200 gph and 3/4 inlet / 3/4 outlet. My professional opinion would be that you will lose flow due to increased head if you go to a 1" return. The chiller has a 1" outlet so that installation would not be limited to a 3/4" return which is probably the average size for return lines.

Anyway. Just my .02 cents. Hope it helps.

- Dean
Nope...look up equations for head pressure. Perhaps your confusing head loss and head pressure. Head pressure is height dependent....head loss deals with restriction due to frictional effects, bends, lengths, orifices, etc...

[CoryDude]

With the 4ft of head pressure, and all the bends I'm running about 700 gph with the mag12. The plan is to have all rigid plumbing except for a small piece of flexible tubing from the pump to help with vibration noise.

its pretty much what I have now, but my new 1/2 hp commercial chiller had 1 inch connections so that's where the thought came from on the 1" lines.

[kkiel02]

Oh ok my old 180 had a setup like that. Now I run rigid drains and flex returns. Sounds like you already did the math so you should be good to go.