Controllers
To make a water pump automatically turn on when you need water, and then to turn off again when you’re finished, can be achieved in a number of ways;
Pressure switch, with expansion tank (images)
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| Pressure Switch |
Pressure switch operated pumps are the basic starting point. They have been around forever. With a pressure switch operated pump, you also need a pressure tank or cell. This tank acts as a reserve of water (under air pressure), waiting to be used. The pressure tank contains a bladder. Water is forced into the bladder (the lower half of the tank) from the pump. Air sits in the top of the tank, and is kept at a certain pressure via a (tyre) valve on top of the tank
The pump starts up and fills the pressure tank with water. When the pressure of the water hits (typically) 40psi, the pressure switch will turn the pump off. When you open a tap, the water is forced out of the tank by the air pressure. Initially the water comes out at 40psi, but as the water drains out of the cell, the pressure reduces. When the water pressure drops to 20psi, the pressure switch cuts in and turns the pump on. The pump will continue to run until the pressure in the pressure tank builds up to 40psi again, and the pump will then turn off.
Let’s say you have a pump capable of 50 litres per minute, and a pressure tank with a draw-off ( water capacity) of 5 litres. You are having a shower, which uses 10 lpm. The pressure in the shower starts off at 40psi. after 30 seconds the pressure has dropped off to 20 psi, because you have used up the 5 litres in the tank, and the pump then cuts in (the size of the pressure tank determines how much water comes out, and therefore how quickly the pressure drops off.). The pump then turns on. You are still using 10lpm in the shower, the pump is capable of 50lpm, so the excess water goes back into the pressure tank. When the pressure in the tank again hits 40psi, the pressure switch turns the pump off again..
The pump turning on when the pressure drops, and then turning off as the pressure builds up, is called cycling. This is the down side to pressure operated systems. This fluctuation of pressure is most notable in the shower. How noticeable it is depends on many factors; size of the pump, size of the pressure tank, size of your plumbing pipes and the distance between the pump and the shower. To overcome this problem, there are now electronic controllers available that ensure constant pressure.
Pressure switches come in various shapes and sizes. Some include a Loss of Prime device, to shut down the pump in the event of no water (these have limited effectiveness?) |
Electronic Controllers
An electronic controller is a device that, when you open a tap, senses the drop in pressure in your pipe system, and turns the pump on. They do not require the use of a pressure tank. The pump stays on for as long as the water continues to run. The pump only turns off when the controller senses a loss of flow. These controllers ensure constant pressure.
A problem occurs however, if you are using a very small amount of water, typically 1 to 2 litres per minute. If that is the case, then the controller will turn itself on and off (cycle). This normally only occurs when toilets are filling, and is not a real concern. If float operated, stock troughs are being used, we would then recommend that a pressure tank be installed into the system.A similar problem occurs if you have any leaks in the system. With a pressure tank system, 5000 drops of water might occur before the pump turns on to build up the pressure. With an electronic controller, perhaps only 20 drops will be enough to turn the pump on. Either fix the leaky taps, or install a pressure tank to get around the problem. |
Presscontrol
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| PressControl |
MiniPress/EcoPress |
MasControl |
ControlPress |
Made in Italy, and used by many water pump companies throughout the world. Onga use it as their main controller. Davey used it on some of their models, until they re-developed their own product.
MiniPress, MassControl & ControlPress are variants of the PressControl.
Click here for more information on these products.
- Starts and stops the pump with the opening and closing of the taps.
- Maintains constant pressure during delivery.
- Replaces the traditional expansion tank system.
- Stops the pump in the case of water shortage, protecting it from dry running.
- Overcomes the effects of water hammering.
- Maintenance-free
| Single phase power supply voltage |
230V |
| Acceptable voltage variations |
± 10% (207 to 253v) |
| Frequency |
50-60 Hz |
| *Maximum current - resistive loads |
16 amp |
| *Maximum current - inductive loads |
8 amp |
| *Maximum power |
1.5 kW (2 HP) |
| Maximum operating temperature |
65c |
| Maximum operating pressure |
10bar (100 metres) |
| Min.flow req'd to keep pump running |
0.6 LPM |
| Friction Loss thru the Presscontrol |
| LPM |
10 |
20 |
30 |
40 |
50 |
60 |
70 |
80 |
90 |
100 |
| loss in Metres |
1.8 |
2 |
2.5 |
3.3 |
5.4 |
5.6 |
7.0 |
8.7 |
10.5 |
12.8 |
| Available in 150kpa or 220kpa cut in pressure |
| 150kpa = highest point of water must not exceed 15 metres |
| 220kpa = highest point of water must not exceed 22 metres |
The pressure generated by the pump must be at least 1 bar (14psi higher than the restart pressure of the device. The pressure exerted by the water column that delivers to the device must be less than the restart pressure of the device.
* = For direct switching-larger motors can be switched via a contactor or relay
Click here to view the Davey data sheet & Instructions for PressControl
Click here for more details on PressControl
Click here for more details on MiniPress
Click here for more details on MasControl/ControlPress
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Davey “Torrium“
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| Torrium |
- Capacities to 170 lpm (10.5 meters loss in pressure)
- Maximum pump motor size – 1,800 watts
- 2 models - pump shut-off head range; T45 = 150 to 450kPa T70 = 450 to 700kPa
- Maximum ambient temperature 50C
- Maximum water temperature 70C
- Minimum water temperature 1C
- starts pump on pressure drop
- stops pump on low flow (~2 lpm)
- measures the pump shut off head each time the pump stops, and sets the cut-in pressure at 80% of shut-off head, so that the consumer is unlikely to notice any pressure change when the pump is switched on.
- adapts each time the pump stops, thus allowing the system to accommodate variations in pump performance or site conditions.
- “loss of prime” = stops the pump, thus protecting the pump from dry run damage •
- Action after “loss of prime” - waits 5 minutes then goes into auto retry mode, whereby it will restart the pump to see if prime can be re-established automatically. Auto retry occurs at 5 minutes, 30 minutes, 1 hour, 2, 4, 8, 16 and 32 hours. Torrium® will also retry if it detects flow through the system (eg from mains water pressure returning).
- detects slow leaks and attempts to overcome the short run times such leaks can cause by dropping temporarily the cut-in pressure to 50% of the last shut-off head. Torrium® will return to 80% cut-in pressure after 100 cycles or if a manual reset is initiated
- in-built spring loaded pressure tank, overcoming the need for regular pressure vessel air charging and checking. Reduces water hammer
Indicator and fault LED system.
| Red constant |
system is in standby |
| Green constant |
pump is running |
| Amber constant |
system in Cistern Fill mode. Detects frequent short cycling, such as slow filling toilet cistern. The pump will then continue to operate for at least 2 minutes |
| 1 red LED flash per sequence |
loss of prime |
| 2 red LED flashes per sequence |
Excessive electrical current, such as when a the pump motor is subjected to lock rotor or when someone tries to manually override the Torrium® by holding in the prime button, |
| 2 red flashes per sequence, over the green run LED |
low incoming voltage (below 180 volts) it will allow the pump to continue to operate if possible, but it will flash. |
3 red LED
flashes per sequence |
Water over-temperature (pump shuts down at 70c.) provides a second level of protection against loss of prime and / or closed head operation and / or repetitive cycling for added security and longer life.. Once the water temperature has dropped to below 60ºC, the Torrium® wil allow the pump to restart. |
| Friction Loss |
| LPM |
0 |
25 |
50 |
75 |
100 |
125 |
150 |
175 |
| Metres lost |
0 |
0.3 |
0.7 |
1.9 |
3.4 |
5.3 |
7.7 |
10.7 |
Click here to view the Davey data sheet or instructions |
Davey “Rainbank”. Onga “Waterswitch”
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| Rainbank |
Waterswitch |
Are controllers which have been specifically designed as water saving devices, for use with mains water in suburbia.
If there is water in the water tank, then the water pump will be used to supply water to the laundry, toilet or garden tap. (where mains water is available, it is currently illegal to use tankwater for any other purpose).
If the water tank is empty, the controller automatically switches back to mains water.
Davey Rainbank is available on two above ground pumps (HP45-05 & HS50-06), and one submersible pump (D42 A/B)
Click here to view the Davey data sheet or instructions
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Davey Monsoon 3V
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| Monsoon |
The Davey Monsoon 3V is a variable speed, commercial controller, capable of running up to 3 pumps at the same time. As the pressure drops to a certain point, the first pump will ramp up in speed until a certain pressure is reached. If this point cannot be met by the first pump at its maximum speed, then the second pump will ramp up. Again, if the second pump cannot attain the set pressure, then the third pump will be called into action. The pumps will start up in rotational sequence. The unit provides full protection, diagnostics and reporting. |
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