Booster pumps Q n A

Discussion in 'Irrigation' started by WalkGood, Jun 22, 2011.

  1. WalkGood

    WalkGood LawnSite Bronze Member
    Posts: 1,910

    I don't know much about booster pumps except that they boost pressure very well. Question is, can they boost flow (gpm) much?

    Residential system. HO added booster pump for whole house. Said neighborhood pressure had gone down in recent years (maybe added development) and water authority did not help.

    Seems that most zones (12 total ) work very well with the pump. One problem zone has 4 PGP rotary heads (#7 nozzles) along with 3 Hunter PS side strip heads at the curb. My pressure gauge at valve box hose bibb shows 30 psi, and I calculate about 14.3 gpm via nozzle sizes.

    Meter (in basement) is 3/4" copper supply and 5/8" meter. Other zones flowing at mid/low 40's psi. All while booster pump is running.

    Incidentally there is (was) a zone with a single spray head on it (for a 2' x 2' bed at garage). While it runs, booster pump brings pressure to just over 90 psi.

    If the problem zone is turned on first, not all the PGP heads will pop up w/o assistance. But if the booster pump had just been on and it had raised the pressure, then the heads will pop up. But not strong. Heads turn slowly.

    I did separate the 3 sprays (added to single spray zone), leaving the 4 PGPs on the original zone. Heads pop up stronger , seem to flow faster, further etc. Pressure while running is 40psi, booster pump is on. Flow via nozzle charts should be 12 gpm.

    I woulda thought the booster pump could have provided enough volume and pressure for the 4 PGPs plus the 3 sprays.

    I suppose there could be a flow restriction in that particular zone. Or maybe there just isn't enough water available in the water main?

    Thoughts ?
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,719

    Pumps never boost flow. They just add pressure. On most homes, the smallest jet pump is more than you need, and almost enough to create negative pressure on the suction side.
  3. WalkGood

    WalkGood LawnSite Bronze Member
    Posts: 1,910

    It would seem that when the pressure is boosted, there is more water coming out of the fixture. The supply pipe did not get thinner.
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,719

    Well, duh. Simple math. The suction end of the pump can have a pressure so low that nothing would flow from any fixture, and the pump creates all the pressure seen downstream.

    I've seen booster installs where only the sprinkler system got boosted, and the house plumbing pressure actually dropped to less than zero.
  5. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,393

    boots is correct, if ya dont boost the whole house, the system will be stealing from the house.
  6. jcom

    jcom LawnSite Senior Member
    Posts: 791

    OK. Look at your GPM charts and as the psi goes up so does the GPM. As we all know that higher pressures equate to higher GPM on our head, how can WB say that a booster will not increase flow as it increases PSI??

  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,719

    You mangle the word problem. Say you have a system running 12 gpm zones, with 30 psi in the house when the system is running. if you walked up to the 5/8 meter in the basement, and calmly removed the outlet tailpiece, you could clock the meter, and observe a flow of 15 gpm, on the way to the basement being flooded. Now you add a small booster pump, and add one head to each zone. Clock the meter again, and you will observe a 15 gpm flow, while the sprinklers outside have whatever pressure the pump can add.

    It's still the same flow. The pump did not increase it. It just made the flow at zero house pressure usable for sprinkling, and did so by adding pressure. Pumps add pressure.
  8. Because after the boost no flow will be had. You can't suck what can't be provided.

    Boots explained it better. It stole pressure from elsewhere.
  9. hoskm01

    hoskm01 LawnSite Fanatic
    Posts: 5,690

    Your mom adds pressure.
  10. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,983

    The best way to trash a booster pump is to think you can get more gpm from it. :hammerhead:


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