Adjusting Grundfos MQ 45 pump

[@ntme9]

My Grundfos MQ3-45 240v is still running strong after 9 years. I had an issue where I would hear it power on (humming) but not pump water for a few seconds then kick in and then you could hear it push water. I thought at first it was the pressure switch but after thinking it through realized it was the capacitor. Instead of buying the exact replacement, which was pretty expensive, so instead I purchased one off amazon with the same specs (but different dimensions) a (CBB60 Motor AC 450V 40uF) for 17.99 and let it hang out the side. It worked perfect and starts pushing water immediately now.

[@jeremiahblair5816]

this adjustment is so the pump will turn on sooner as the water pressure drops? Currently the pressure in my water system drops too low before the pump kicks on, I need to pump to cycle earlier , will this adjustment raise the pressure that the system drops to before the pump cycles on (so the pump kicks on sooner)?

[@HPL5P]

Why did you make this adjustment?

[@ethersecure2432]

And that was the last time anyone ever saw Steve and Bob again...

[@gmctech]

So whats stopping me from driling a god damn hole in the back of the housing so i can do this with it all together and no guess work as the gauge will show me whats what in real time?

[@moimemesuis]

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

[@travistaylor509]

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.)

[@curio124]

​@@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.

[@jerkster9114]

Why didnt the manufacturer give us an adjustment screw outside the pump?

[@samdaniel5703]

Do i need to add a regulator and a check valve to this i was thinking about putting a 50-100 gallon tank after my pressure tank so i can run my house on this pump? Will that work? Ive acquired this unit for free. The reason for doing this is so when my water outside my house befor e it enters the house sometimes it pulls all the water and no water in the house and the well pump has to build back up. Hince the 50-100 gallon storage tank with this pump could it work?

[@markhenshaw2574]

I just adjusted my pump as in the video. I wanted to lower the total pressure. Here's what happened. I adjusted the switch out 1/2 turn. The "cut in" pressure went to 25 PSI from 50 or so, and the pump cut out pressure stayed the same at 65. I was hoping to reduce the Overall pump pressure.

[@andywazy4383]

Did he forget to plug the pressure switch back into the mother board?

[@hugohidalgo5708]

I have question what happened when the pump running every three minutes

[@MrSavage77]

Thanks for the hint. Still, what are jumpers on the board for?

[@samuelclark7005]

My pumps starts and pumps fine but every 11 seconds it cycles off and immediately back on...it "pulses" is this what needs adjusted?

[@stefaangoeman6019]

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

[@surfgeorge]

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.

[@robertgraefe6205]

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

[@briankennedy7345]

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

[@briankennedy7345]

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

[@pfmcdermott1]

How did this end up working? Does it cycle on and off more, or does it just pump up the small pressure tank that much higher s it cycles on and off the same but just provides more pressure? Thanks for the video! It was great to see this adjustment.

[@johnpiatek1588]

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

[@hpthynne]

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.

[@johnpiatek1588]

It cycles on quicker. Pressure is the same.

[@johnpiatek1588]

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.

[@ntme9]

@@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?

[@SK-wf1oh]

how to set up start pressure? it's possible or it was programmed permanently

[@perceval7790]

Hi, I wonder if you can tell me how it is possible to connect a water pressure tank to this pump....Should I connect a pressure switch somewhere connected also to the pressure tank??? thaks

[@johnpiatek1588]

You'll need to write to Grundfos for that

[@perceval7790]

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

[@johnpiatek1588]

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.

[@robertgraefe6205]

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.

[@moimemesuis]

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

[@briankennedy7345]

Hi all, I tried this on mine, 2 half turns, 1 at a time, however it is still cycling 11secs on, 20 secs off. Could this be a capacitor issue? Thanks for any info, and thanks for the videos!!

[@AN-ks2ep]

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

[@SereneVaIIey]

Why is it that even if no one uses the faucets the pump automatically turns on evryvtwo minutes??

[@jeremiahblair5816]

Because you have a leak somewhere

[@ProfessionalsAutoBody]

My pump turns on but wont shut off, any suggestions?

[@johnpiatek1588]

You need a service call or write to Grundfos for troubleshooting

[@skipjohnson6881]

This video does not tell you to relieve the pressure by finding the valve under the round cover in the back. You then have to recharge after adjusting.

[@ChasingRuben]

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 .

[@SK-wf1oh]

in my case I couldn't see any differences after turning 90 degrees

[@youtucciuniverse6925]

My pump stays running at 45 psi. The built on pressure tank was full of water. Would this be the cause? And if so, anyone have a grundfos pressure tank they wanna sell for $5 bucks?

[@GTerplan]

I'm not sure if your still monitoring this, but I have the mq35 and it has the same components. I have turned that pressure screw once as in the picture and again the same amount since it didn't change anything the first time and the pump still only kicks on at 30psi. I would like to get this to 40psi if possible.

[@johnpiatek1588]

Write to Grundfos and find a local service tech

[@j1284]

So mine will not turn on when I run my water, unless I run a sink and a shower and something else. I can hear a small rattle when water is flowing through it when the pump is not on. I checked the flow switch and it seems to be free of any debris. Will adjusting the screw help?

[@trujillor84]

When u work with electrical components you have to take off all metal from your body (like that ring 💍)... u know... for safety😁

[@peterfaulk4630]

Don't do this. These pumps are designed to not be adjusted for a reason.

[@juanrividdi7504]

hi! My pump turns on but won't turn off, any suggestions?