Grundfos MQ Booster Pumps
For Low Water Pressure

Grundfos MQ Water Pressure Booster Pumps

Grundfos constant speed, low water pressure MQ booster pumps are designed for domestic applications where low noise is a major consideration. The water cooled unit eliminates the need for noisy cooling fans. THESE UNITS ARE VERY QUIET.

Pump Capacity Table In Gallons Per Minute
Model	HP	Volts	Water Outlets At the Same Time	Discharge Pressure (PSI)							Shut-off (PSI)
				30	35	40	45	50	55	60
				Gallons Per Minute (GPM)
MQ3-35-115	3/4	115	Up to 3	13	10	6	4				50
MQ3-35-230	3/4	230	Up to 3	13	10	6	4				50
MQ3-45-115	1	115	Up to 5	18	16	14	12	10	8	5	68
MQ3-45-230	1	230	Up to 5	18	16	14	12	10	8	5	68

All calculations are based on 3 GPM per outlet.

Do not exceed 75 PSI discharge pressure to prevent damage to piping.

Inlet pressure plus maximum pressure boost equals total discharge pressure.

Use a pressure regulating valve in the inlet and /or outlet lines as required.

Maximum Flow Rate Of Typical Residential Water Meters
Meter Size	Maximum Flow (GPM)	Caution
5/8"	12	Before ordering the booster system
3/4"	30	make sure that your water demands
1"	40	do not exceed the maximum flow rate
1-1/4	65	of your house water meter..

GRU-PMP-MQ-Boosters-Bulletin.pdf	GRU-PMP-MQ-Boosters-Manual.pdf
GRU-PMP-MQ-Boosters-Check-List.pdf	GRU-PMP-MQ-Boosters-Adjustment.pdf
GRU-PRT-MQ-Boosters-Parts.pdf	GRU-PRT-MQ-Boosters-Electronic-Replacement.pdf
GRU-PRT-MQ-3-45-Kit-Components.pdf	GRU-PMP-MQ-Warranty-Statement.pdf

Questions & Answers

What causes the MQ to start?

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.

What causes the MQ to stop?

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.

What is the maximum height recommended between the MQ and any tap?

To allow for the pressure of 50 ft of water, tolerances and a safety margin, Grundfos recommends a maximum height of 50 ft between the MQ and any tap 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).

What is the purpose of the built-in pressure tank?

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.

How is the dry-run condition determined?

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.

What is the maximum inlet pressure allowed in the MQ?

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.

Where can a pressure gauge be easily installed?

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