Because you have a leak somewhere

no, if capacitor faulty pump will hum and no turn or completely not working

in what case you have to relieve the pressure of the valve? if you wanna made start the pump with low pressure? mine isturn on when the pressure drops to 35 psi .

the rubber cover and that the adjusting screw is under power all the time.

Have you had any luck figuring yours out? I just bought a house with one of these (installed 2013) and realized it never kicks on. Gauge pressure before the pump is about 40-45 psi. I am guessing pump inlet pressure never drops low enough. So why is the pump even here, just seems like a restriction. Water pressure is adequate but it's not 65 -70 of my old place (borderline too high per home insp.)

​@@moimemesuis this is not correct. I've dismantled whole sensor and it's actually super simple mechanism. If you look at it (for example 3:54) it consists of 2 halves. 1st half is "water" half, it let the water in, but the water is blocked by silicon membrane - so it's closed "cave". 2nd half is "electric" half, but there is actually just 1 stupid microswitch (close/open circuit) without any electricity. Water press on that silicon membrane, that membrane press on a big plastic button and if that big button is pressed enough, it press the microswitch. That screw just increase/decrease a tension on a spring, that press the big button against the water pressure. So it's actually a good idea to drill a hole to the housing and remove that rubber plug (-: You can easily dismantle whole thing. No worries. There is nothing you can break or crack. My pump had an issue that every 10-15sec of water delivery it turned off for a second. I guess that that spring just lost some strength over the time and it can't hold the pressure of the water anymore. I had to remove the whole sensor like 20x, because the correct spot was in a very tiny area. I've moved it 3 degrees more pump never stop (even without water delivery), I've moved it 3 degrees less and 10-15sec pauses were there again.

I have the same problem, i try to found out what's wrong, i think the pressure switch that is bad

Exact same timing (11 on, 1 off). Anyone got an answer? This is a brand new pump that was stored in the original box in a dry location for a number of years. It's also quite noisy compared to the identical model it replaced.

Check for a leak somewhere it doesn't take much. Leaky fawcet, leaky toilet or a small leak anywhere.

surfgeorge did you get to the bottom of this issue? Mine is 11 secs on, 20 off. Curios, thx!

Stefaan Goeman did to u get to the bottom of this issue? My pump is cycling 11secs on, 20 secs off. Thx!

You'll need to write to Grundfos for that

and they told me to look page 21 of their fucking PDF which said nothing

It should work with a pressure tank but you would need the owner's manual to see how it's done. Other than that your well guy or plumber should be able to help you out.

BS. Just hook it up on the pressure side of the pump. Grundfos product manual and customer support suck. I have just installed a pressure tank and it eliminates the short cycling. I may increase the low factory pressure setting at a later date.

@@robertgraefe6205 Yes, I did replace a normal pump in a hydropneumatic system by this pump, leave the tank installed and works wonderfully.

You need a service call or write to Grundfos for troubleshooting

Write to Grundfos and find a local service tech

It just changes when the pump kicks on. Doesn't change anything else

Thanks for the potentially helpful video. Would this adjustment resolve a delayed starting issue with the pump? My pump sometimes takes anywhere from a a few seconds, to a few minutes to start when a tap is opened. It has worked flawlessly since 2008 until now. Thank you.

It cycles on quicker. Pressure is the same.

Resolves delayed starting but it's normal for the pump to take a few seconds to kick on. It is activated by pressure drop and/or flow. If there is too much back pressure in the lines (as in the case of larger pipes with long runs) it takes a long time for the pressure to drop to around 25 psi when the pump kicks in. That's where the adjustment really helps.

@@johnpiatek1588 So this just adjusts the turn on pressure? But you said if you turn it too far it won't cut off. So doesn't that mean this adjusts the turn off pressure?