Jet pumps in series or parallel?

Timco

I have a 3/4hp 12GPM jet pump pressurizing my irrigation main and I need a bit more flow. I cut a floor mount B&G inline and it worked great but it’s not exactly the same size. I’ll buy an identical pump but what’s the performance difference for pumps In series or parallel?

Pumpguy

Parallel doubles the flow rate with the same discharge pressure.

Series is in fact a 2 stage arrangement, so this increases the discharge pressure, but not the flow volume.

hot_rod

Got adequate pipe size to move the extra gpm? Doubling the pumps will provide more flow. More flow through the pipe raises the head of course, so you may not double the flow at the end of the line.

Timco

This is what I Did and it really throws better now! It’s all 1” system. Some zones have 8 heads at 3gpm each so I need better delivery in those zones. It’s how we bought it. I added the red pump today.

hot_rod

24 gpm would be a lot to shove thru a 1" pipe. But if you are getting the sprinkler coverage you need with the series pumps, that is the win.

Timco

I’ll never get 24GPM but better is acceptable given the alternative. My wife has me adding some heads too. What I can’t wrap my head around is pressure vs flow or series vs parallel. I’m running the pressure switch to 60psi. If I’m looking for more water but not more pressure then parallel is best?

hot_rod said:

24 gpm would be a lot to shove thru a 1" pipe. But if you are getting the sprinkler coverage you need with the series pumps, that is the win.

EBEBRATT-Ed

Changing one thing affects everything else. If the pipe size and heads are causing restriction then series will overcome the added head (hopefully). Two pumps in parallel with the same head will only pump tp that head.

Put a flowmeter and some gauges on it to approximate the head

hot_rod

Think of it like a hydronic system. If you knew or could calculate the pipe length, fittings, heads, etc you could come up with a head number. Say if you want 20 gpm at that head, look to the pump curve.