2 x 1.5 inch pipes into one

[Ian_montreal]

Hi,

I currently have one pump with a 1.5 inch exit. I'd like to add a second one but I'm reluctant to drill another hole in my foundation.
would it still work if the two pumps go into one exit? I could possibly make the exit a bit bigger say 2 inches? or 3?

logically doubling the output should require 3 inches, I'm just trying to avoid complicating things.
two inches would be easier as I can prob make the hole in the foundation slightly larger.

Thanks!

 

[Valveman]

You can only squirt so much water through a 1.5" pipe no matter how many pumps you have. Are these sump pumps?

 

[Ian_montreal]

You can only squirt so much water through a 1.5" pipe no matter how many pumps you have. Are these sump pumps?

yes sump pumps. each has a 1.5 out.

 

[MicEd69]

logically doubling the output should require 3 inches

That is not correct logic. You need to double the "area" of the pipe, not the "diameter" of the pipe for increased flow.

A 2" pipe will provide you with about an 89% increase over a 1 1/2" pipe. So, going to a 2" pipe should be close enough for you. You will restrict the flow some, so the pumps will pull back on their curves and the flow rate will be slightly decreased, but probably not enough where you could tell. A sump pump has other restrictions like check valves, fittings, and discharge height above the pump.

 

[Ian_montreal]

That is not correct logic. You need to double the "area" of the pipe, not the "diameter" of the pipe for increased flow.

A 2" pipe will provide you with about an 89% increase over a 1 1/2" pipe. So, going to a 2" pipe should be close enough for you. You will restrict the flow some, so the pumps will pull back on their curves and the flow rate will be slightly decreased, but probably not enough where you could tell. A sump pump has other restrictions like check valves, fittings, and discharge height above the pump.

Thank you for correcting me. This is good news to me and I will therefore go with a 2'' pipe.

Thank you very much

 

[Pipe Dreams]

Thank you for correcting me. This is good news to me and I will therefore go with a 2'' pipe.

Thank you very much

I think the 1 1\2 would be fine in that application

 

[Ian_montreal]

I think the 1 1\2 would be fine in that application

so you don't think I have to change my 1.5 pipe ? two 1.5 into one 1.5 would be enough?

 

[MicEd69]

Here's a quick explanation of pumps and fluid flow. This is a basic pump curve.



"Head" is the pressure the pump puts out. As you can see, as the flow decreases, the more pressure the pump can produce.

As flow rate increases through a pipe, friction loss causes a reduction of pressure in the pipe. The more flow rate, the higher the "backpressure" there is on the pump, and the lower the flow rate the pump can develop.

So, using two pumps in a 1 1/2" line is entirely possible. However, as valveman said, "You can only squirt so much water through a 1.5" pipe no matter how many pumps you have." The system will work just fine if you maintain the 1 1/2" discharge line, but the pumps will pull back along their pump curves and the flow will be reduced. A 2" line will reduce the amount of friction loss, and the pumps will run out further on their curve and pump more water.

I hope this helps.

 

[Pipe Dreams]

so you don't think I have to change my 1.5 pipe ? two 1.5 into one 1.5 would be enough?

In your application, i think it would be fine, unless of course one pump is not keeping up with the demand of an area. I suppose you are adding another pump in another location becasue water is accumulating somewhere else that would not otherwise so into the other sump.

I do not know why you are adding the other pump, but for a general sump pump, 1.5 would work fine. Even if they were to kick on at the same time. Pumps work better and last longer at 80%+ load. If it were my project I would connect them together ( existing line ), If I were to install both as new, I would probably upsize to 2'' just becasue.