Herbie Drain

[CountryBoy72]

I have a 110G tank that has a corner overflow with two holes drilled in the bottom of the tank. The Tank came with one 1 1/2" an a 1" pvc pipes. One hole will be my main drain an the other will my emergency drain. I have another hole drill in the back of the tank for my return. Does it matter which one of the two different size pvc pipes I use for my main drain ? Should they both be 1" diameter ? I also have the gate valves needed for the setup.

[aleonn]

I also have a corner overflow tank with a 1.5" main drain, and 1" backup drain (180 gal tank). I'd use the larger size PVC pipes as the main drain. Using the 1" as the main drain, you're limiting the flow in your sump, and might have more noise/turbulence in the pipes compared to a larger PVC pipe.

[CountryBoy72]

Thanks, Do you know which one you put the gate valve on, or do you put them on both ?

[CountryBoy72]

Aleonn do you have a gate valve on your main drain pipe ?

[TJQ]

The Gate valve goes on the main drain. That's how you regulate the flow which also controls the water level in the tank. The emergency drain(s) go straight into the sump with no regulation.

[uncleof6]

Originally Posted by aleonn

I also have a corner overflow tank with a 1.5" main drain, and 1" backup drain (180 gal tank). I'd use the larger size PVC pipes as the main drain. Using the 1" as the main drain, you're limiting the flow in your sump, and might have more noise/turbulence in the pipes compared to a larger PVC pipe.

This is exactly opposite from what it should be. You ALWAYS want your emergency drain to be capable of handling MORE flow than the main drain. In other words, the larger size is the emergency. A 1" siphon is well capable of handling 1500 -1800 gph without coughing. It use will in now way limit the flow rate in the sump.

What you have is a large diameter pipe, handling what a 1" will handle, and probably have a valve closed pretty far on the 1.5" line. This can make for some noise, and other issues. The 1.5" line is actually unnecessary, and a 1" would take its place with no issues. The 1" emergency, would still have more flow capability than the 1" siphon, because the siphon is valved back a small amount to raise the water level in the overflow.

A heavy restriction in the 1.5" line, will cause enough pressure differential, to suck air past the seals in, say for instance, a union directly below the valve........not too mention such would make a bit of noise.

At these flow rates, there will be no noise, or turbulence in the lines unless there is an air leak. Noise and pressure loss in a 1" pipe does not occur till around 3500 gph.

[uncleof6]

Originally Posted by TJQ

The Gate valve goes on the main drain. That's how you regulate the flow which also controls the water level in the tank. The emergency drain(s) go straight into the sump with no regulation.

The valve on the siphon is only used for raising the water level in the over flow. Flow rate control, is accomplished by a valve on the pump outlet. Just to keep things clear. Flow rate is never controlled with a valve on the drain line.

[aleonn]

I never thought of that, it does make perfect sense. Can you explain what you mean in BOLD?

Originally Posted by uncleof6

This is exactly opposite from what it should be. You ALWAYS want your emergency drain to be capable of handling MORE flow than the main drain. In other words, the larger size is the emergency. A 1" siphon is well capable of handling 1500 -1800 gph without coughing. It use will in now way limit the flow rate in the sump.

What you have is a large diameter pipe, handling what a 1" will handle, and probably have a valve closed pretty far on the 1.5" line. This can make for some noise, and other issues. The 1.5" line is actually unnecessary, and a 1" would take its place with no issues. The 1" emergency, would still have more flow capability than the 1" siphon, because the siphon is valved back a small amount to raise the water level in the overflow.

A heavy restriction in the 1.5" line, will cause enough pressure differential, to suck air past the seals in, say for instance, a union directly below the valve........not too mention such would make a bit of noise.

At these flow rates, there will be no noise, or turbulence in the lines unless there is an air leak. Noise and pressure loss in a 1" pipe does not occur till around 3500 gph.

[uncleof6]

Originally Posted by aleonn

I never thought of that, it does make perfect sense. Can you explain what you mean in BOLD?

Acts as a venturi. A similar thing happens when a pump cavitates... it sucks air past the volute seals. Pressure differentials. Sudden pressure drop inside.