Sprinklers have very low pressure

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nofx1728

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I have a cheap DRUMMOND 1 HP Cast Iron Shallow Well Pump With Pressure Control Switch. I have 6 zones on a 1/4 acre lot with only 4-5 heads running at a time. The pump had not run in a few months and it was failing to prime so I called a sprinkler and irrigation company out to fix my sprinklers. It cost me $400, he removed my pressure tank, replaced my sprinkler timer and wired the pump directly to the timer to turn on/off and draw water, replaced check valves. He never mentioned any potential issues with the size of the pump. The pump is intaking 50psi if the discharge is shut off to the sprinkler heads, but drops to 10-15psi when water is going to the sprinklers. Now the guy is telling me I need a new pump and that this one is not large enough.

Questions:

1. If I had a pressure tank still attached would it resolve the lack of psi? Is this going to burn my pump up even if i buy a new pump?
2. If some of the heads were clogged/leaking would this cause that significant of a drop in pressure? Trying to decide if I should try replacing all the heads prior to getting a new pump.
3. Does it sound like I need new pump?
4. How bad did this guy rip me off?
 

Valveman

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A pressure tank is not going to help. The pump must supply as much water as the sprinklers are using or the pressure will be low. Clogged heads would cause higher pressure, but leaking could drop the pressure. Your pump must be large enough to supply the amount being used and/or leaking. The old adage that you get what you pay for comes to mind. That is a cheap pump and not designed to pump much water or pressures more than 50 PSI.

In the manual is says...

3. This pump should NOT be used for:
Continuous run,
fountain/pond water features.
Water with dirt and debris.\

Any pump not designed for continuous use is not good for irrigation or much of anything. When you run sprinklers the pump needs to run continuously as cycling on and off will greatly shorten any pumps life. Even though it is also a 1HP, it won't hold a candle to a good pump like a Goulds J10S. But even then you need the right number of sprinklers for the pump being used.
 

WorthFlorida

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For Florida with a high water table, a 1.5 HP irrigation pump is about the minimum size you need. Most of Central and South Florida the table may only be about 5' from hydrostatic pressure. For Florida most irrigation installers use 1" pipe to feed each zone before splitting down to 3/4" or 1/2" to the sprinklers. Pump intakes are usually 2" and anything less for irrigation will only work for small areas as you have.

Florida irrigation companies are licenced and the tech must pass a test for certification in irrigation, therefore, most irrigation guys know what they are talking about and know what works and doesn't. As stated by the irrigation guy and Valveman, you never want or need a pressure tank for irrigation. Irrigation & pool pumps do not have pressure switches and by the way, they usually use the same motors. The pump sections are designed differently.

When water is flowing, pressure will always drop. What irrigation needs is volume plus good pressure. The owner's manual and sales literature does list irrigation use but not at the performance you want. This pump set up is good for a small home with one or two people such as at a cabin. The price shown is $199 and I guess - a coupon, irrigation pump from HD @ 1.5HP is $257. A 1.5 hp can be wired for 220v or 110v operation. 2 HP is 220v only. https://www.homedepot.com/p/Everbil...CH=REC-_-plpbrowse_multi-_-NA-_-300534068-_-N

This is from the Harbor Freight website. Another spec sheets reads a 1-1/4" inlet.
  • Designed for use in residential potable water systems
  • Fully automatic operation with pressure switch
  • 50 PSI maximum discharge pressure
  • 30 PSI on / 50 PSI off
  • High output flow within full pressure range
  • Heavy duty cast iron pump housing
  • Powerful and quiet operation
  • Reliable 1 HP motor
 
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