# keep pump running at high pressure with pressure switch

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#### RTL

##### Member
Are you saying that the pressure rises high enough to shut off the 40/60 psi pressure switch, even if the sprinkler system is running? 90 feet of head is only 39 PSI, so I would not expect the pump to shut off while the sprinker is running.

Now if the pump delivers more pressure while the pump is running, maybe adjusting the pressure switch higher would work for you.

So yes, you could switch a relay to convert between using the pressure switch and being always on. But I don't think you would need that.
I'm trying to figure out how to keep my pump running (always on) while the sprinklers are running while still having a pressure switch and tank. Can I utilize a pump relay with a pressure switch and how do you connect it?

#### Reach4

##### Well-Known Member
I'm trying to figure out how to keep my pump running (always on) while the sprinklers are running while still having a pressure switch and tank. Can I utilize a pump relay with a pressure switch and how do you connect it?
I have no experience with irrigation pumps.

If you parallel contacts of the pump relay with the contacts of the pressure switch contacts, then either the relay or pressure switch calling for water would turn on the pump.

So maybe have a 30/50 pressure switch, or adjust that to say 28/48, would work, without danger of the pump shutting off during irrigation.

Do you understand wiring contacts in parallel? For 2-pole pressure switch and pump relay, there would be 4 new wires involved.

#### Bannerman

##### Well-Known Member
If I turn the pressure switch up o 53 the pump doesn't turn off
the pump is 75 psi 2 HP and tops out at about 51 psi on the gauge.

Don't know how you would know that without bypass the switch to let the pump dead head for a minute? Specs say 147' which is 63 PSI max

You are basing 51 psi on a system pressure gauge reading that you are not certain is accurate. If the pump is actually capable of producing either 75 psi, or 63 psi, with the pressure switch adjusted higher so the pump does not shut off, then the system pressure directly after the pump at the pump's elevation, should max out fairly close to either 75 or 63 psi.

Perhaps the pressure is actually higher than 51 as Valveman is suspecting.

Before making any adjustments to the pressure switch, test the system gauge accuracy by activating the pump and then stop all water use. Once the pressure switch shuts off the pump @ 51, immediately measure the pressure tank air pressure using a known accurate tire pressure gauge so as compare the air pressure reading to the system gauge reading.

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#### Bannerman

##### Well-Known Member
Since the pump is shutting off while the irrigation system is running, that would usually signify either, 1) the pump is supplying more water than is exiting out through the sprinklers (most likely), or, 2) the pump is overheating and is being shut down by a thermal overload switch (less likely).

If #1, a CSV that is calibrated appropriately, can easily remedy the situation as the CSV will reduce the delivery rate from the pump to equal the rate of flow exiting the sprinklers, which will cause the pump to continue running for the entire time the sprinklers are in use.

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#### RTL

##### Member
You are basing 51 psi on a system pressure gauge reading that you are not certain is accurate. If the pump is actually capable of producing either 75 psi, or 63 psi, with the pressure switch adjusted higher so the pump does not shut off, then the system pressure directly after the pump at the pump's elevation, should max out fairly close to either 75 or 63 psi.

Perhaps the pressure is actually higher than 51 as Valveman is suspecting.

Before making any adjustments to the pressure switch, test the system gauge accuracy by activating the pump and then stop all water use. Once the pressure switch shuts off the pump @ 51, immediately measure the pressure tank air pressure using a known accurate tire pressure gauge so as compare the air pressure reading to the system gauge reading.
I was able to adjust the cutoff up to 57 psi and the pressure on the tank matches the gauge

#### RTL

##### Member
Since the pump is shutting off while the irrigation system is running, that would usually signify either, 1) the pump is supplying more water than is exiting out through the sprinklers (most likely), or, 2) the pump is overheating and is being shut down by a thermal overload switch (less likely).

If #1, a CSV that is calibrated appropriately, can easily remedy the situation as the CSV will reduce the delivery rate from the pump to equal the rate of flow exiting the sprinklers, which will cause the pump to continue running for the entire time the sprinklers are in use.
Valveman is saying it won't work unless my pump can create 65 or more psi

#### RTL

##### Member
I have no experience with irrigation pumps.

If you parallel contacts of the pump relay with the contacts of the pressure switch contacts, then either the relay or pressure switch calling for water would turn on the pump.

So maybe have a 30/50 pressure switch, or adjust that to say 28/48, would work, without danger of the pump shutting off during irrigation.

Do you understand wiring contacts in parallel? For 2-pole pressure switch and pump relay, there would be 4 new wires involved.
Not sure how to wire them in parallel

#### Bannerman

##### Well-Known Member
Valveman is saying it won't work unless my pump can create 65 or more psi
I understood that response was referring to the CSV you already possess, not a CSV that is appropriately calibrated for your system's actual pressure range.

#### RTL

##### Member
I understood that response was referring to the CSV you already possess, not a CSV that is appropriately calibrated for your system's actual pressure range.
Valveman "a CSV at 50 PSI cannot deliver 50 PSI unless the pump can make about 63 to 70 PSI at deadhead so a 35/55 pressure switch will work." My pump is currently making 56 maybe 57. I also thought that the CSV should work if it only allows 50 psi through

#### Reach4

##### Well-Known Member
Not sure how to wire them in parallel
Looking at https://www.rainbird.com/products/psr-universal-pump-start-relay (there are others)

They show two model numbers. I kinda think the same diagram applies to both, but I could be mistaken.

Actual wire colors don't matter much, except ground should be bare, or green, or special yellow+green. The wires shown in orange, red. blue. and black could all be black, or all red, or all blue.

Thing on the left is a Rain Bird universal pump start relay. Thing on the right is a common pressure switch. If this mostly makes sense to you, ask specific questions. If you are lost, confer with a friend who has some electrical knowledge.

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#### Bannerman

##### Well-Known Member
What Valveman is saying is, the pump must be capable of delivering a higher margin of pressure than the CSV is configured to deliver.

For example, on a system equipped with a 30/50 psi pressure switch, a CSV will be usually calibrated to deliver 40 psi consistently.

To ensure 50 psi will be reliably achieved to shut off the pump, even when the water level within the well has dropped lower than usual, thereby making it more difficult for the pump to achieve it's usual maximum pressure, it's best to utilize a pump that is capable of even higher pressure such as 53-60 psi or greater for a system with a 30/50 pressure switch, and a CSV calibrated to deliver 40 psi.

For you to utilize a CSV calibrated to deliver 50 psi, your pump would need to be capable of 63 to 70 psi deadhead pressure. Since you previously stated your pump could only achieve 51 psi, implying it was deadheading at 52 psi, there would be insufficient margin to utilize a 50 psi CSV, but, you may be able to utilize a CSV that is calibrated to deliver 38 or maybe 40 psi consistently.

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#### RTL

##### Member
What Valveman is saying is, the pump must be capable of delivering a higher margin of pressure than the CSV is configured to deliver.

For example, on a system equipped with a 30/50 psi pressure switch, a CSV will be usually calibrated to deliver 40 psi consistently.

To ensure 50 psi will be reliably achieved to shut off the pump, even when the water level within the well has dropped lower than usual, thereby making it more difficult for the pump to achieve it's usual maximum pressure, it's best to utilize a pump that is capable of even higher pressure such as 53-60 psi or greater for a system with a 30/50 pressure switch, and a CSV calibrated to deliver 40 psi.

For you to utilize a CSV calibrated to deliver 50 psi, your pump would need to be capable of 63 to 70 psi deadhead pressure. Since you previously stated your pump could only achieve 51 psi, implying it was deadheading at 52 psi, there would be insufficient margin to utilize a 50 psi CSV, but, you may be able to utilize a CSV that is calibrated to deliver 38 or maybe 40 psi consistently.
Considering the equipment I have it does not appear a CSV will work. My pressure switch is set to turn off the pump at its highest pressure of 56 and it cuts in around 36 which does not supply enough psi to run the sprinklers at the top of the hill. I'm losing 25 psi due to the head.

#### Reach4

##### Well-Known Member
At 56 psi, the sprinklers are drawing and emitting water, right? Can you or your irrigation controller shut off the path to the sprinklers? If your pump can develop 56 psi at the pressure switch while the sprinklers are on, I would think the pump could develop significantly higher pressure with the sprinklers off.

#### RTL

##### Member
Looking at https://www.rainbird.com/products/psr-universal-pump-start-relay (there are others)

They show two model numbers. I kinda think the same diagram applies to both, but I could be mistaken.

Actual wire colors don't matter much, except ground should be bare, or green, or special yellow+green. The wires shown in orange, red. blue. and black could all be black, or all red, or all blue.

Thing on the left is a Rain Bird universal pump start relay. Thing on the right is a common pressure switch. If this mostly makes sense to you, ask specific questions. If you are lost, confer with a friend who has some electrical knowledge.
This is exactly what I've been looking for on-line and couldn't find. My only concern would be supplying the pump with 2 sources of power at the same time. I would think that the pressure switch contacts would not close since the pump is running and producing psi.

#### RTL

##### Member
At 56 psi, the sprinklers are drawing and emitting water, right? Can you or your irrigation controller shut off the path to the sprinklers? If your pump can develop 56 psi at the pressure switch while the sprinklers are on, I would think the pump could develop significantly higher pressure with the sprinklers off.
56 psi with sprinklers off. Pump specs say 75 max, but no idea why it only produces 56. Could be that the water supply is more than 10 feet.. no idea. I just need the pump to stay running while the sprinklers are on so the pump start relay piggy back seems to be the simplest way to solve the problem.

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#### Reach4

##### Well-Known Member
56 psi with sprinklers off. Pump specs say 75 max, but no idea why it only produces 56. Could be that the water supply is more than 10 feet.. no idea. I just need the pump to stay running while the sprinklers are on so the pump start relay piggy back seems to be the simplest way to solve the problem.
What is the pressure with the sprinklers on?

Note that the pressure gauge, the pressure switch, and the input to the pressure tank should be very close to each other. Pressure drops in pipes that are carrying water. A nipple, even a long one, will not have pressure drop due to flow, because there is no significant water flow to the pressure gauge or pressure switch.

You understand that having the contacts in parallel does not change the source of the pump power. Controller power does not go to the pump. Controller power does go to the input of the relay, which powers an electromagnet. The electromagnet just moves the switch without providing electrical power to the relay contacts.

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#### Valveman

##### Cary Austin
Staff member
56 psi with sprinklers off. Pump specs say 75 max, but no idea why it only produces 56. Could be that the water supply is more than 10 feet.. no idea. I just need the pump to stay running while the sprinklers are on so the pump start relay piggy back seems to be the simplest way to solve the problem.

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I think it only produces 56 because that is the off setting of the pressure switch. If you tighten the large adjustment screw about 3 full turns to the right I bet it will shut off at 63 and maybe even 75 PSI. With either of those numbers the CSV125 will give you 50 PSI while the sprinklers are running, as long as the pump can do that.

The problem with the pump start relay is that it can start the pump yet not tell the sprinklers to come on. This will deadhead the pump and it will sit there at 63 or 75 PSI until the pump melts down. A pressure switch is just safer, you just have to prevent the pump from cycling.

#### RTL

##### Member
I think it only produces 56 because that is the off setting of the pressure switch. If you tighten the large adjustment screw about 3 full turns to the right I bet it will shut off at 63 and maybe even 75 PSI. With either of those numbers the CSV125 will give you 50 PSI while the sprinklers are running, as long as the pump can do that.

The problem with the pump start relay is that it can start the pump yet not tell the sprinklers to come on. This will deadhead the pump and it will sit there at 63 or 75 PSI until the pump melts down. A pressure switch is just safer, you just have to prevent the pump from cycling.
What is the pressure with the sprinklers on?

Note that the pressure gauge, the pressure switch, and the input to the pressure tank should be very close to each other. Pressure drops in pipes that are carrying water. A nipple, even a long one, will not have pressure drop due to flow, because there is no significant water flow to the pressure gauge or pressure switch.

You understand that having the contacts in parallel does not change the source of the pump power. Controller power does not go to the pump. Controller power does go to the input of the relay, which powers an electromagnet. The electromagnet just moves the switch without providing electrical power to the relay contacts.
A few days ago I was able to adjust the psi up to 56 from the 52, but anything more and the pump will not shut off.

The pressure with the sprinklers on is controlled by the pressure switch 36-56.
The sprinkler valves are about 20 feet higher than the pump, would this have anything to do with why the pump is only creating the 56 psi?
My pressure tank is a couple of feet from the switch/gauge due to location restrictions.

Is it common for the sprinkler timer to call for the pump in error?

#### Valveman

##### Cary Austin
Staff member
Is it common for the sprinkler timer to call for the pump in error?
It is a common failure mode of a pump start relay. In some areas it is more common than others as it has to do with varmints and electrical damage to the wires that go to the sprinklers. Wires to the sprinklers or zone valves get damaged and the pump start relay doesn't know the sprinklers didn't come up. Adding a pressure relief at like 75 PSI is the normal way to protest from melting the pump down when this happens. But with a pump that only builds 56 PSI that won't work.

But pump start relays are used all the time. Just wire as instructed above. Probably less expensive to replace the pump if something happens than to try to protect it from problems. If the amps drop noticeably when the pump is deadheaded, a Cycle Sensor would sense that and shut the pump down.

#### RTL

##### Member
It is a common failure mode of a pump start relay. In some areas it is more common than others as it has to do with varmints and electrical damage to the wires that go to the sprinklers. Wires to the sprinklers or zone valves get damaged and the pump start relay doesn't know the sprinklers didn't come up. Adding a pressure relief at like 75 PSI is the normal way to protest from melting the pump down when this happens. But with a pump that only builds 56 PSI that won't work.

But pump start relays are used all the time. Just wire as instructed above. Probably less expensive to replace the pump if something happens than to try to protect it from problems. If the amps drop noticeably when the pump is deadheaded, a Cycle Sensor would sense that and shut the pump down.
I'm being told a check valve can reduce the psi by 5 psi. I'm at ~56-7 with check valve installed after the pump so if I add 5 psi that would be the 63 the pump can produce with the 60 foot of head. Sound right? Mfg recommended check valve after the pump and I have no room to install before the pump.

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