pump o ring sliping out of housing when pump shuts off

11 years ago

The O ring in my 2 HP pool pump gets bumped out of its slot whenever the sprinkler controler shuts off the pump. There seems to be a tremendous back pressure!! I have to re insert the o ring by hand because the pump now will just suck in air. I just built the system so I may have missed a part. Is there some kind of back flow pressure devise for controling this back flow of water into the pump? I am using a lake and a 2 hp pool pump that pushes 80GMP . Is this overated? Should I be running 3 or 4 zones at the same time.

Comments (4)

trkpoker
11 years ago
You should NEVER use a pool pump for a sprinkler pump. There are many reasons...you have found one. Need to take the pump back and buy a sprinkler pump. They work differently. 80GPM on a pool pump and 80GPM on a sprinkler pump are a world apart. Not going to look it up but for 80GPM on a sprinkler pump you would need a pump 5HP or larger. How many gpm is running on your zones? Count the heads (and type of head) so you get a feel about what size sprinkler pump you need.

Good luck,
Tom
jonathanteller
Original Author
11 years ago
Thanks for your imput! ...too late for taking it back. rain bird designed my system for 30GPM. How about if I 'T' off close to the pump and send a bunch of water staight back into the lake.
Also I could install a back flow preventer to stop that huge back rush of water into the pump.
What do you think? Maybe I'll discover some other of those reasons why never to use a pool pump . I don't mind sacrificing the pump now, but I don't want to damage any other parts of my sprinkler system.
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jonathanteller
Original Author
11 years ago
Ok That worked! A check valve cured the backflow problem, and I diverted 50% of the water straight back into the lake to solve the (overated pump) problem.
I am now interested to discover which if any are those other problems that can occur using a pool pump as a sprinkler pump?
trkpoker
11 years ago
One of the main reasons you don't use a pool pump for irrigation is because of the pumps head pressure and flow. Pool pumps are designed for low(ish) pressure and high flow where sprinkler pumps are designed for a bit lower flow but more pressure. Sprinkler heads require a certain amount of pressure to properly spray out the water so coverage is even and gets out to the intended distance. Some heads wont even pop up if the pressure is too low.

One example is a pop up rotor head. There are many different brands with different requirements but one example would be a rotor requiring 5gpm @ 32+psi. Under 32psi the head will not properly preform. Under 20 psi and he head might not even turn. Under 15psi and it might not even pop up.

If your system attains high 20s psi or better you should be fine.

Good luck,
Tom