Maw Solutions Ltd    Henfield, W Sussex    Phone: 01273 493343    Email: info@mawsolutions.com

The manufacturers of our electric water pumps, Davies Craig, have developed pump speed controllers which are designed to ensure that the volume of coolant being pumped around an engine and through the radiator is varied according to how hard the engine is working.  The Controller uses a probe located inside the engine’s water jacket (eg inside the thermostat housing) to sense engine temperature, and translate this temperature into a variable voltage. Then, the higher the temperature, the greater the output voltage, and so the faster the pump rotates, and the greater the volume of coolant flow.

A pump controller is only required in installations where the electric pump is the only pump. If the electric pump is installed to assist a mechanical pump, then it should be controlled by a switch. Basically, the Controller is performing two main functions. Firstly, it is acting as a thermostat by limiting coolant flow until the engine has warmed up - initially pulsing the coolant, and then gradually speeding the pump up.  And secondly, once the engine has warmed up it varies coolant flow to maintain engine temperature at the preset level, so minimising wasted pump power and optimising engine operating conditions.

There are currently two models of Controller, the microprocessor-based model (part no. 8010) introduced several years ago to match the  EWP80 pump (pictured above),  and the newer Digital Controller (part no. 8020) which was launched in late 2006 to match the EWP110.    Both Controllers will drive the EWP80, but only the Digital Controller has the extra current capacity to drive the more powerful EWP110.

Key Features Comparison

EWP80 Controller 8010 Digital Controller 8020 Output Voltage 3 volts - 12 volts 5 volts to 13.5 volts Maximum Output Current 7.5 amps 12 amps Controlled engine temp 75-100 deg C (preset) 75 / 80 / 85 / 90 / 95 deg C Weight 300 grams  (10 oz) 90 grams (3.2 oz) Size 95mm x 65mm x 50mm 101mm x 95mm x 35mm Heat Soak Run-On Possible Automatic 2 minutes Indicator LEDs None Temp, Power ON, Pump mode and Test Remote Fault Indicator No Yes

Both Controllers need to be mounted inside the car, away from the harsh under-bonnet environment, and are supplied with sensors and colour-coded wiring harnesses for connection to the pump.  Both Controllers allow the pump to run on after engine shutdown, to reduce heat-soak effects, but the Digital Controller gives an automatic 2 minutes run on.  The older Controller doesn’t begin to pump coolant until the engine temperature reaches 20 degrees below the preset temperature, whereas the Digital Controller pulses the pump (10 seconds on, 30 seconds off) from engine start-up. The Digital Controller is a more expensive unit, but offers a wider and more user-friendly range of facilities, including a built-in diagnostic system, using the 8 integral LEDs to display fault conditions.  For more information on the Digital Controller, or on how to install it, click on one of the links below.

Please feel free to phone us on 01273 493343 to talk about your application.