Grundfos MQ... stops and starts again with a ... tap

[Marco T.]

I ask you for help and advice in understanding what the problem may be before throwing the pump in the garbage. As you can see in the video it starts then stops and starts again after a shot in the pressure tank.

My idea is to replace the pressure tank but I want to be sure that the problem is there before spend money in a old pump.

Any suggestions will be appreciated

Thanks
Marco

 

[Reach4]

I ask you for help and advice in understanding what the problem may be before throwing the pump in the garbage. As you can see in the video it starts then stops and starts again after a shot in the pressure tank.

Nothing in your video resembles a shot or a pressure tank.

I suspect if you look at a pressure gauge hooked to the input of the pressure tank, it might tell you something.

 

[Sponsor]

 

[LLigetfa]

...before throwing the pump in the garbage

Here is a pic that valveman likes to use.

 

[Valveman]

Lol! I hope being predictable is a virtue? Anyway, there is a flow switch that turns the pump off. The flow switch moving up can also turn the pump on, or it will come on at a lower pressure from the internal pressure switch. I don't think tapping on it will move the flow switch up, so it must be starting with the pressure switch. Then when there is no flow the flow switch shuts it off again. Could be the pressure switch or the main electronic board. Probably going to need a bigger hammer. Lol!

Replace it with a regular jet pump and a PK1A. No electronics to fail and bullet proof enough to last 30-40 years.

 

[Marco T.]

Lol! I hope being predictable is a virtue? Anyway, there is a flow switch that turns the pump off. The flow switch moving up can also turn the pump on, or it will come on at a lower pressure from the internal pressure switch. I don't think tapping on it will move the flow switch up, so it must be starting with the pressure switch. Then when there is no flow the flow switch shuts it off again. Could be the pressure switch or the main electronic board. Probably going to need a bigger hammer. Lol!

Replace it with a regular jet pump and a PK1A. No electronics to fail and bullet proof enough to last 30-40 years.

View attachment 72337

Thanks for your suggestion, simple things without electronics are the best and here in Italy I find "simple" pumps of all kinds, even economic ones. The problem is that the pump is right attached to the wall of my condo and next to the door of my bedroom ... I had to put this pump because it is silent otherwise the hammer was bought by my neighbors....

I started doing other investigations and I discovered some water under the pressure switch... this is not a good sign...

 

[Valveman]

Simple is good, but economic can be the same as cheap. Cheap bearings and windings not made for continuous duty make for pumps that don't last very long. Grundfos makes good pumps, the MQ is just not one of them. The JP series is good, but has an air cooled motor that will cause more noise. You can't get much more quite than the water cooled MQ, but that is because it is broken and isn't even running most of the time.