Question about Grundfos MQ3-45 1 HP Pressure Booster Pump

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Has anyone at this site had much experience with a Grundfos booster water pump and its dependability?I am considering the purchase of one for my daughter's home. She has a 1500' entrance water pipe running up a very steep hill. Due to this, her water pressure never exceeds 33 PSI. She would like to have 50 to 60 PSI for her washer and dish washer use.

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You would be better off with a brand that has better representation than Grundfos. Several of our commercial customers change to brands such as Armstrong or Bell & Gossett the first chance they get because Grudfos is less reliable and getting parts or service on them much harder.

Posted on Apr 29, 2010

Testimonial: "Thank you for the info. It was appreciated."

  • abbott210 Oct 19, 2010

    I have a Grundfos MQ3-45 that lasted only about 2 years and the replacement parts are VERY expensive. Can you provide me with a website to order a different brand at the best rpice?


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Posted on Jan 02, 2017

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My grundfos water pump has low pressure

I had the same problem with a Grundfos pump, I spoke with the team at, they recommended a booster pump which done the job. Worth a phone call.

Jan 14, 2015 | Cars & Trucks

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Grundfos pump problems

There are several possibilities here. All involve water pressure. The first is that you have a water leak between the pump and where the water is going to.
The second is that the pump is not getting enough water to it so it is sucking air well as water in an attempt to give you water perssure. This could be caused by not having an inline "one way" valve on your supply line just before the pump ($30.00).
The third involves two little screws on the control where your electical connection is. These two screws control the high and low pressure settings of your pump. If your high setting is too high the pump will simply keep running trying to do the impossible, If there is not enough difference between the high and low setting the pump will also keep on. running.
Another possibility is that the pump has had debris (sand, dirt, mud, etc) sucked through it and has damaged either the housing or more likely the impeller that spins the water creating the pressure.Ther is also an internal seal that can be damaged by debris.
The final possibility is that the pressure control unit with the two little screws I mentioned earlier has failed and is deffective.

Most importantly if the pump is running hot please stop using it! You are at risk of fire and possibly the loss of your home and loved ones. Grundfos pumps can be serviced by a professional technician, Parts are readily available and not extremely expensive. I would not recommend doing it youself if it is the some specialty tools may be involved depending on the problem. You will become frustrated very quickly.
A fast solution is to buy one of the cheap plastic pumps ($169.00) made in China. They are amazing for the price and will run with no problems for years if your water is free of debris. Fixing your Grundfos may run you the same amount and you maybe without a pump for a week or more depending on the technicians work load.
I am not saying "Don't fix your Grundfos" but you don't need to be in a panic about it either.

Sep 06, 2014 | Grundfos JPS4 1 HP Pressure Booster Pump

1 Answer

I have installed a Grundfos CH2050PT pressure booster system at my home (3 stories). The pumps is installed at ground level and is connected to the main water tank (source of water). The pressure is...

it could be the differential in pressure between the cold water from your booster pump and the hot water from your solar water heater . the cold water which feeds your solar heater is probably being reduced in pressure by a pressure reducing valve . so what you need is equal pressure on both your hot and cold water system you could install a pressure reducing valve on the pipe thart feeds your cold taps etc valve set at the same pressure as the one on the solar water heater that would give you a balanced hot and cold water system

Dec 07, 2010 | Grundfos JPS4 1 HP Pressure Booster Pump

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...

1 Answer

House pressure water pump has to be reset to

it sounds like a relay for the auto shut off ....

Jan 16, 2010 | Grundfos MQ3-35 3/4 HP Pressure Booster...

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