The MQ is equipped with both an internal flow switch and pressure switch. Each of these can turn the MQ on depending on water consumption. The pump will start when the flow rate is greater than 0.3 gpm OR the pressure is below 29 psi.

Other than the manual on/off button, only the flow switch will automatically stop the MQ during normal operation when flow drops below 0.3 gpm. The pump will shut off in 12-15 seconds after flow stops. Additionally, the MQ will be turned off in the event of a dry-run or over temperature alarm.

If a tap or faucet is installed at heights greater than 50 ft above the MQ, there is the potential risk that the MQ will never start. In cases where the MQ starts due to low pressure (low flow rates), the pressure has to fall below the pressure switch activation point (28-30 psi factory setting). To allow for the pressure of 50 ft of water, tolerances and a safety margin, we recommend a maximum height of 50 ft between the MQ and any tap.

The built-in pressure tank comes from the factory pressurized at approximately 23 psi (with the pump pressure at zero), and holds a volume of 5 ounces of water. It is designed to minimize motor startup due to small leaks.

The dry-run alarm is declared when the motor is running AND the flow rate is less than 0.3 gpm AND when pressure is less than the pressure switch setting. When this condition lasts for 1 minute, the alarm is declared and the motor is stopped. The MQ attempts to automatically restart every 30 minutes for a maximum of 24 hours. If more than 24 hours pass without water, the pump must be restarted manually.

For both MQ 3-35 and MQ 3-45 the maximum internal pressure allowed is 109 psi. The maximum inlet pressure when added to the MQ pressure must not exceed 109 psi. Remember that inlet pressure adds to the MQ pressure, so with a 40 psi inlet pressure supplied to the MQ 3-45, internal pressures can reach approximately 105 psi (65 + 40 psi). Additionally, if inlet pressures exceed the built-in pressure switch activation point, (28-30 psi factory setting) the pressure switch will be unable to activate, and the ability to turn the MQ on at low flow rates will be lost. In this situation, only the flow switch will be able to turn the MQ on at flow rates above its activation point of 0.3 gpm.

In the ½" straight thread opening used to add priming water to the pump.