Question about Grundfos MQ3-35 3/4 HP Pressure Booster Pump

1 Answer

Why does my Grundfos MQ water pump keeping kicking on, even when there is no water demand?

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  • 485 Answers

Is it newly installed or has it been working for a while till you noticed it?

Posted on Jan 16, 2014

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6 Suggested Answers

6ya6ya

6ya staff

  • 2 Answers

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Posted on Jan 02, 2017

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Anonymous

  • 31 Answers

SOURCE: Voltage at pump is 120 & air pressure in tank

it sounds like the pressure sensor or switch is bad.

Posted on Nov 10, 2009

Kieran Ruppert

  • 990 Answers

SOURCE: With the water running the MQ pump runs intermittently

This is a problem with your bladder in the pressure tank or the pressure switch. Ether one will produce this cycling on and off. Good luck.

Posted on Mar 09, 2010

Anonymous

  • 1 Answer

SOURCE: My Grundfos MQ pump intermittantly continues to run

I have the same problem and have found that the inlet check valve has a broken shaft in the center of device. It is a multi-piece plastic unit and it looks as if it is not quite seating and therefore the internal pressure leaks slowly back into my low pressure suction line. The pump will start and the pressure will build then shut off for about 30 minutes then cycle again. I am going to replace the check valve.

Posted on Apr 18, 2010

jgwhomeequip

Jeremy Reddick

  • 1902 Answers

SOURCE: I have a problem with the MQ-35 pump starting and

This sounds like a issue with air still being in the system and not being removed from the system to make things work properly. I did try to findthere number and was unable to locate it. The only other option for you is to return the product and find one with better support

Posted on May 04, 2010

Tom W

  • 760 Answers

SOURCE: Grundfos pump leaking?

If it is starting and stopping, it most likely does have some type of leak. The check vavlve is normally installed on the suction side of the pump, and sometimes instead of a check vavlve or in addition to, there is a foot valve. A foot valve is just a check valve (usually with a screen) at the end of the line in the bottom of the cistern. If you have much suction lift, and the check valve leaks (or any leak in the suction piping) then the water will drop back into the cistern. This will also cause the discharge side of the pump system to drop in pressure, causing the pump to restart. You mentioned removeing the pressure tank, that tank keeps the pump from short cycling when you have low demand on the system. If the pump is higher than the cistern, and you don't see a check valve between cistern and pump then you most likely have a foot vavle in the cistern. Hopefully it's accessable by removing the pipe.

Posted on Aug 01, 2010

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1 Answer

No water


Does the motor turn it self off after a couple of minutes of no pumping?= ran out of water. If there is water up to the pump and still no water, check filter/s ( if there is any). Undo V band and check pump internals, impeller may be broken from shaft? When putting back together tap V band with block off wood or back of screw driver evenly as you do up the clamp to stop it distorting

Apr 14, 2014 | Grundfos Pumps Grundfos MQ 3-45 1 HP...

1 Answer

Grundfos pump


Louise, since there is several different types and models of Grundfos pumps it would be hard to answer your question. To possible point you in the right direction below are a few links to where you can find some PDF documentation about a popular Grundfos pump the MQ series and direct link to the manufactures "Service Support".

Service support
Grundfos MQ Series Pumps

Feb 07, 2014 | Garden

2 Answers

Grundfos MQ pump starts every 15 seconds


Pressure is bleeding back through the pump or system to the tank or well or where ever the water is coming from. Should be some sort of one way valve to keep water from going back to the source, mounted somewhere so that once pressure is pumped up, it will hold that pressure in the part of the system that has the pressure switch that controls the pump.

That or you have a leak where you can't see it. (Actually you do, it is just internal and not leaking outside the pipes!)

Nov 04, 2012 | Grundfos Pumps Grundfos MQ 3-45 1 HP...

1 Answer

Low pressure from grundfos pump to house


Does your system equipped with pressure tank (pneumatic tank)? If it has, maybe it's already filled with water due to some pinhole leaks. Drain the tank and see what will happen.

Oct 30, 2012 | Grundfos Pumps Grundfos MQ 3-45 1 HP...

1 Answer

I have a problem with mq booster pump every 10 seconds kicks back and kicks on i am check the showers no leaks everything is ok please tell what can be a problem


Grundfos said the problem of on off every few seconds was air in the line. Then

later admitted it was the control unit. After replacing two units in 2 yrs I replaced

it with a standerd pump pressure switch.....Runs fine

Nov 17, 2011 | Grundfos MQ3-35 3/4 HP Pressure Booster...

1 Answer

I have a grundfos mq 35 pump to boost pressure in my hot and cold system. due to loss of water recently pump ran dry and shut down. when water returned the system was restarted and pump reset. we now get...


There was possibly some damage done to the pump while it was operating dry and it in now not able to deliver the required flow of water. Pumps wear very quickly when allowed to run dry, even for a short time.

Jan 02, 2011 | Grundfos JPS4 1 HP Pressure Booster Pump

1 Answer

Grundfos pump leaking?


If it is starting and stopping, it most likely does have some type of leak. The check vavlve is normally installed on the suction side of the pump, and sometimes instead of a check vavlve or in addition to, there is a foot valve. A foot valve is just a check valve (usually with a screen) at the end of the line in the bottom of the cistern. If you have much suction lift, and the check valve leaks (or any leak in the suction piping) then the water will drop back into the cistern. This will also cause the discharge side of the pump system to drop in pressure, causing the pump to restart. You mentioned removeing the pressure tank, that tank keeps the pump from short cycling when you have low demand on the system. If the pump is higher than the cistern, and you don't see a check valve between cistern and pump then you most likely have a foot vavle in the cistern. Hopefully it's accessable by removing the pipe.

Aug 01, 2010 | Grundfos MQ3-45 1 HP Pressure Booster...

1 Answer

I have a problem with the MQ-35 pump starting and running for about 10 minutes when there is constant demand (such as running a sprinkler) and it then alarms and shuts off for 30 minutes before it will run...


This sounds like a issue with air still being in the system and not being removed from the system to make things work properly. I did try to findthere number and was unable to locate it. The only other option for you is to return the product and find one with better support

May 04, 2010 | Grundfos MQ3-35 3/4 HP Pressure Booster...

2 Answers

With the water running the MQ pump runs intermittently


This is a problem with your bladder in the pressure tank or the pressure switch. Ether one will produce this cycling on and off. Good luck.

Mar 09, 2010 | Grundfos MQ3-35 3/4 HP Pressure Booster...

2 Answers

My Grundfos MQ pump intermittantly continues to run when there is no demand, especially after drawing off a small quantity of water. It then overheats. The plumber has replaced the pressure tank but the...


I have the same problem and have found that the inlet check valve has a broken shaft in the center of device. It is a multi-piece plastic unit and it looks as if it is not quite seating and therefore the internal pressure leaks slowly back into my low pressure suction line. The pump will start and the pressure will build then shut off for about 30 minutes then cycle again. I am going to replace the check valve.

Mar 06, 2010 | Grundfos MQ3-35 3/4 HP Pressure Booster...

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