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How to Adjust a Pressure Switch

Learn How to Adjust a Pressure Switch

Question from: Todd L. – Reno Nevada

How to Adjust a Pressure SwitchColleen, I would like to learn how to adjust a pressure switch so we will have higher water pressure  in our home. I checked the bladder in my pressure tank and it’s set to 18 psi, does that mean the pressure switch is set to 20/40?  How do I know how many turns on the pressure switch to increase it to 30/50 or 40/60 PSI, this is so confusing!

Our water pressure is very low and my wife is complaining about it all the time, now I find myself turning to another woman for the right answer!  I have phoned around and no one seems very helpful, I am just baffled.  Thanks again Colleen, I have turned to your other website many times over the years. I appreciate your commitment and endless articles, you’ve even responded to my emails before!

Response: From Colleen Roberts


Thanks Todd, glad to see you back…
I do remember you!  Ok, let’s get the wife happy!

WARNING: And I do mean WARNING Todd… before you ever touch a pressure switch you must power down your system, that means cut the electricity to your well pump. Common sense would lead us to believe that there should be a quick disconnect right near the pressure tank, but common sense does not always prevail. If there is not a way to cut power / electricity at the pressure tank you will need to do so at your electrical panel… if you’re not very clear on this Todd you must not touch the system, please call a professional. Even after you have powered down Todd please test to be sure, never assume… always be sure!  I tend to always go the the electrical panel anyway the find the correct breaker.

Unless you know exactly what you are doing you really should not be messing with a pressure system, those of us who do this work are trained and familiar with checking on other issues that you may not notice.  However, I will answer your question… but I advise extreme caution when working with electricity and pressure systems.

Personally, I find 20-40 PSI to be an intolerable water pressure and unless there is some question of the ability of the pump to handle a higher pressure, the pump must be able to easily build pressure so let’s assume that it’s an able pump. I believe that 30-50 is the lowest pressure acceptable to take a half-way decent shower with but 40/60 is better if you want to make the wife really happy Todd.  The first thing you need to do is connect a hose to the hose-bib at the bottom of the pressure tank and completely drain off the tank.  Close the valve but leave the hose connected so you can test later.

I think that it’s a good idea to either check that the pressure the gauge is reading is correct or install a new gauge, the nipples can become restricted or plugged. The air in the tank should be 2 lbs less than the kick on pressure (when the pump engages), if you are currently at 18 lbs then adjust when the tank is completely drained of water, if you are running 40/60 then you will want 38 lbs of air.

As you’re adding air keep checking the tank air pressure with a tire gauge. If it is too high, bleed a little air pressure off.  If it’s too low, add air with a bicycle pump or compressor. There’s also no set run that you need to adjust to 30/50 or 40/60 you could have 35/55 – 45/65 but I would not tighten down too much… as you will risk the contacts not opening,  keep in mind that it’s recommended that a 20 lb differential between on and off is maintained. Far to often I have seen an 30/50 over tightened… don’t do that just go get the 40/60 switch. They are the least expensive part of your entire system and vital effective operation of your water system!

You will notice the tall nut with the spring to the left and a short to the right. I typicallt use a 3/8 box end wrench.

You will notice the tall nut with a spring to the left and the short to the right. I typically use a 3/8″ box end wrench again you do not want to over tighten… this could cause the pressure switch to malfunction.

If the cut-on/cut-off is 40/60 psi is what the factory setting is on the pressure switch. A 20 psi differential is standard and recommended.  You can adjust the differential by turning the short adjusting nut on the pressure switch clockwise to increase or counter-clockwise to decrease the differential, it’s seldom required and I suggest you not tamper with this setting unless you know what you are doing.

Adjust the long thread nut in the pressure switch to the right to increase pressure (each complete turn should increase the pressure about 1-1/2 lbs.)  You should no need to adjust the short nut, that’s the differential and is factory set at 20 lbs… let it be.  Just adjust the tall nut as you can see in the photo.

Please note:  we generally purchase 30/50 or 40/60 in domestic switches, you can also purchase with a low pressure cut out (little brass lever to the side) and that’s a whole other topic. Personally I REALLY dislike low pressure cut out switches and feel they’re a really cheap fix for nothing, I never install them. Install proper pump protection equipment if there’s an issue or concern… my advice always is “Do the job right.”

You should be good to go after this Todd, power up the pump and go tell your wife to have a shower… she should be happy!

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  • 3rdworldsavage

    Nice info on pressure switches. Just noticed there is a typo on “too” and “off”. “completely drain of the tank” and “tighten down to much”. Thanks.

  • Adam Lambert

    Hi! Can you explain why a low pressure cutoff is a bad idea? Wouldn’t it keep the pump from running without water?

    • Hi Adam, if you are concerned about the pump it’s much better that you use pump protection. A pump-tec etc. A low pressure cut out switch is not really designed to protect the pump and can cause other issues that are not favorable.

  • Yes Adam that would be one benefit but the best advice for low water is a pump-tec etc best to not depend on a low pressure switch to prevent your costly pump from frying. Low pressure cut-out switches tend to cut out as well draws down… I’m just not keen on them.

  • JesseNY

    Also keep in mind, when you increase the tank air pressure you decrease the capacity a bit. If you get a second tank in parallel or a larger tank you can have both high pressure and high capacity.


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