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Friday, September 16th 2022, 6:51pm

Pump Outlet Pipe Sizing

Hello folks,

Hoping for confirmation. After much frustration, I learned the PVC fitting to my irrigation pump kept coming off due to a stuck relay. Seems it ran and ran until pipe popped out of the outlet, shorted the electrical, blew breaker, etc. Only figured this out after getting a professional to replace the outlet pipe and discovered the pump running while controller was OFF.

My problem is low pressure at the sprinklers now, and valves that seem to want to stay partly open in some zones. The installer chased down stuck valves, only to have another stick partly open. On the stuck zone, pressure is better but not what it was before. Before the repair, the outlet pipe was 1-1/2" schedule 40 with elbow running over to the 1"ish black sprinkler piping. The replacement is 1-1/2" thin wall pipe with reduction elbow to what looks like 3/4" black pipe running about 18" over to the 1"ish black sprinkler piping. BY INSERTING THIS REDUCED SECTION OF PIPE, DID THE INSTALLER CAUSE THE LOWER PRESSURE?

If I partially stepped on a garden hose, I would not be surprised by reduced flow. Feels like this is exactly what is going on with the sprinklers now. Advice? Pump is brand new 1-1/2 HP by the way, inlet and outlet are 1-1/2"

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