Actually, the smaller control sets the differential amount between the low and high cutoffs, that is usually a 20lb difference, such as 30lbs "turn on" to 50lbs "turn off" (the default factory settings), or 40-60, or 45-65, etc. and you really should not mess with it.

Just adjust the longer control, tightening it up to increase both the low and high cutoffs, or loosening to reduce them both.

If you suffer from lower pressure than you'd like, then you do want to adjust both ends of cutoff the same amount.

DS, that's a three year old post, but you are indeed correct. The smaller nut only adjusts the cut off pressure up or down.

Yea, I noticed it was 3 years old, but after seeing various other posts in other Google searches, I thought I'd explain what the service technicians just told me after replacing a bad Square D controller (pitted points).

Just to clarify from them, the smaller nut does not "only adjust the cutoff pressure up or down". In fact, it widens or narrows the default 20 lb gap between the cut in and cut off pressure points. So if you have a lower than desired pressure situation, this is not really what you want to do, and adjusting it too much can cause other problems. To increase your pressure, you want to raise both the cut in and cut off points the same amount, by adjusting only the larger or longer screw in tighter.

My pump has to pump uphill to my house about an extra 10 feet or so vertically over a distance of about 200 feet. So I need more pressure overall than a normal setup. If I were to adjust the smaller screw in an attempt to "raise the cutoff pressure" (the upper limit) as you indicated (and some other posts elsewhere did), it would not really help that much because the lower turn on point would be still the same based on your description. In fact, tightening that smaller screw will increase the separation between the two settings, driving the high cut off point even higher and low cuton point even lower (NOT what you want). Generally you just leave the default 20 lb separation as is.

I see your point. However, remember that the person wanted to know how to raise pressure. The answer I posted stated both how to raise the cut in pressure (large nut) and the cut out pressure (small nut). Both actions will have the result of raising the pressure, one by raising the bottom limit, and the other by raising the upper limit.

I have found the link below to be very reliable. It states, in part, the following: "The nut atop the smaller spring in the pump pressure switch: this nut is used to narrow or widen the gap between the pump cut-on and pump cut-off pressures. This is the right-hand spring (and nut) in our photo).

Turning the small nut clockwise (tighter) will RAISE the CUT-OFF pressure, and vice versa, loosening or turning the nut counter-clockwise will lower the cut-off pressure. Watch out! If you loosen this nut too much you can set the cut-off pressure below the cut-on pressure and the pump will turn on and run forever (or until it burns up.)"


So you are correct in stating that the smaller nut increases the gap between cut in and cut out pressures. It does that by increasing, or decreasing, the cut out pressure, as I stated. I would agree with you that adjusting the larger nut is generally the way to go. I don't see a problem with simply telling the person the function of both nuts.



How to adjust water pump pressure, pump cut-on pressure and pump cut-off pressure - private pump and well system do-it-yourself repairs

Thanks. I think I got some bad scoop from the service technicians who replaced my controller. I found a SquareD document on 9013F Pumptrol Pressure Switch Instruction Card
That shows a picture and gives instructions. (attached a jpg of this) This was somewhat consistent with that on inspectapedia.com that you referenced. However, this SquareD reference didn't mention anything about the large screw adjusting both cut in and cut out as does inspectapedia - which is the net effect I want to achieve. Inspectapedia says it got all its info from SquareD, so we'll go with their explanation.

Thanks again.

Keep posting, DS. You generated a good discussion and found a really good site. Thanks.