Question about Grundfos Plumbing

1 Answer

Grundfos JPF4A pump. takes a long time to get up to prime then once it kicks in after running water it gets to 50 shuts of but drop pressure instantaneously and kicks back in again. The constant on off is a click sound like a car engine starter trying to turn over. It seems like the pump looses pressure to quickly after shutting off and will struggle to get pressure to remain above 30 once it shuts off

Posted by on

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert who has written 3 tips or uploaded 2 video tips.

  • Expert
  • 306 Answers

The check valve is bad. When the system builds up pressure and shuts off the check valve prevents water from dropping back down the well line. When the check valve goes bad water drops back down the well line and siphons water back out of the well tank causing the switch to kick on and off constantly. The check valve will between on the well line coming from the drop pipe. It may be making a constant rattling noise as pump is running. Replace the check valve and you should be fine. Also check the pressure in bladder tank it should be 2psi below the "cut-in" pressure for the switch.

Posted on May 23, 2011

1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I have a pressure booster pump installed which turns on automatically when we open the tap and turns off by itself when we close the tap, but when power goes and comes back(common in india), the pump will...

Check to see if the output pipe has water in it when the pump swutches off the pump needs to be primed at all time what we normally find cases like this is the pump is higher than the supply or there is an air pocket on the output where the pressure sensor is

Dec 16, 2013 | Grundfos MQ3-35 3/4 HP Pressure Booster...

1 Answer

Grundfos ch2-50 is running but it wont stop when the water is not used

This sounds like you have a pressure switch issue.
You can adjust the pressure sensor once you have not load on the pump to stop. If you adjust it and it fails to still shut off than I suggest you replace the pressure switch.

Oct 13, 2013 | Plumbing

1 Answer

Pump will not kick on after pressure drops. Just installed a new pressure switch and pressure tank.

Hi Tony
1. Check your opening to the pressure tank to make sure it is clear and reading the pressure in the tank.
2. Check to make sure that the pressure cut-off of the new pressure swith is at the correct shut-off pressure...if not then the directions that was included in the box with the new pressure swith
Please take time to rate me

Mar 31, 2013 | Star Water Systems 1/2 HP Cast Iron...

1 Answer

Low pressure from a grundfos cr4 pump

that looks like a fun 1 to work on. i think you might have trash in your impeller that will cause a drop in pressure .. this one will take some time to work on.. go slow ! here is a break down

Jan 07, 2012 | Grundfos Garden

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

Pump not priming

If the product category you selected is correct, and you are using this as a pressure booster pump, then you are working with water that is already under some pressure. The booster pump, once it is working normally, would always have water in it and would not have to re-prime itself. To get it primed the first time, you have to bleed the system, which will remove the air. If the exit line from this pump goes up, you should be able to bleed the air by running a faucet. If you are not using this as a booster, but as a primary pump, you have to find a way to get water into the turbine. I have had success using a garden sprayer (with the nozzle removed) and placing the small diameter hose into the turbine in place of a small plug that is there. If you found this useful, please vote.

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

1 Answer

I have a Guundfos CHIE 4 circulation pump that is constantly running. I closed the valve on the pressure side but is still runs. On a previous post I was told it "may have lost its prime". The pump is...

You have a defective pressure switch.But replacing the switch. Do the following; Open the pressure switch cover, and find the two adjusting nuts. One is for the cut-off pressure (40psi) and the other is for the cut-in pressure (20 psi). Adjust the the nut with a longer stem counter clockwise (loose) with the pump running. Take care not to touch the power line attach
to it. Continue the adjustment until the pump stops,
at 40 psi. Then, observe - Pump must stop once the
pressure is attained. Then, open the valve until it
start (20psi).. Then you can adjust the other nut to
cut in at 20 psi.
To prime the pump; open and fill the priming port full
with water.and replace the priming port plug. Set
the water flow control valve at full close position.
Switch the power on to run the pump and slowly
open the control valve to appropriate setting such
that the pump doesn't lost the suction. Send your e-
mail for further comment. God bless u

Aug 07, 2009 | Grundfos JPS4 1 HP Pressure Booster Pump

Not finding what you are looking for?
Plumbing Logo

Related Topics:

432 people viewed this question

Ask a Question

Usually answered in minutes!

Top Grundfos Plumbing Experts

john h

Level 3 Expert

12104 Answers


Level 3 Expert

75817 Answers

Andrew Bugbee

Level 2 Expert

227 Answers

Are you a Grundfos Plumbing Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides