New sump plumbing questions

[erichm20]

I am building a new sump and have a couple questions that I cannot seem to find a clear answer on.

My Dt is 55 g and not drilled so I am using a CPR overflow with a 1" bulkhead which I've read will yield 600 gph. I bought a mag 7 pump and the head loss is 4.5 feet which per the box will be 450 gph. Then there will be a t, a couple elbows, a ball valve and a union which will all decrease the flow rate a little more, maybe another 100 gph.

1. What size plumbing should I use for the return? The pump has 1/2" outlet but I was thinking of using 3/4"

2. Should I decrease the size of the drain line to 3/4" instead of 1"? Does it really matter what size the return line is with a HOB overflow, will the return flow dictate the drainage flow? I guess what I'm asking is could I have a situation where my return pump cannot keep up with the drain?

Oh and I will have a skimmer in the first chamber which is rated for 125 g not sure if that will make any difference.

Thanks

 

[Ingy]

I am building a new sump and have a couple questions that I cannot seem to find a clear answer on.

My Dt is 55 g and not drilled so I am using a CPR overflow with a 1" bulkhead which I've read will yield 600 gph. I bought a mag 7 pump and the head loss is 4.5 feet which per the box will be 450 gph. Then there will be a t, a couple elbows, a ball valve and a union which will all decrease the flow rate a little more, maybe another 100 gph.

1. What size plumbing should I use for the return? The pump has 1/2" outlet but I was thinking of using 3/4"

2. Should I decrease the size of the drain line to 3/4" instead of 1"? Does it really matter what size the return line is with a HOB overflow, will the return flow dictate the drainage flow? I guess what I'm asking is could I have a situation where my return pump cannot keep up with the drain?

Oh and I will have a skimmer in the first chamber which is rated for 125 g not sure if that will make any difference.

Thanks

Although I have a drilled and don't need to worry about an overflow, I did used to work in a steam plant and have a few thoughts.

1" will provide about 600 gph assuming that's O/D of the pipe. That's a max flow and it will only overflow whatever the return pump can provide so don't worry about the return being "overpowered". Skimmer will not affect flow rates.

Headloss doesn't matter wrt pipe diameter. But for every 90 deg bend you put in add about 1' to headloss calc. So 4.5' plus 2 x 90 bends gives 6.5' headloss. Consider 45 bends if it's critical.

Ball valves are really designed for on/off control. They are too difficult to manage flow control. Right now that may not be a concern as I don't think your return will overpower your overflow, a future upgrade might make it so. So the ball valve is good to shut off the water for maintenance on the pump but a GATE valve will allow you to make minute changes to flow.

 

[erichm20]

Thanks for the response! Good to know. Interesting what you said about ball valves not good at controlling flow but better for on/off and gate valves better for controlling flow I thought it was the other way around.

So the drain pipe I'll leave at 1" (OD is about 1.25) and 3/4 should be fine for the return plumbing? Just making sure bc I already have a bunch of 3/4 pieces.