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Plumbing Pro
Plumbing Pro, Plumber
Category: Plumbing
Satisfied Customers: 1284
Experience:  Licensed plumbing contractor state of Il, & Chicago
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Well water... on a 20/40 preset switch can I change it to 30/50

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Well water... on a 20/40 preset switch can I change it to 30/50 if I change the pressure in the tank to 28psi or do I need to purchase a 30/50 switch ...and by doing this will it increase my water pressure?
Submitted: 5 years ago.
Category: Plumbing
Expert:  Plumbing Pro replied 5 years ago.

Plumbing Pro : Welcome to Just Answer, I will do my best to Answer your question to the best of my professional ability.You can respond by typing in the box. A pressure switch just tells when the pump should turn on and off . Often the pressure tank will go bad and cause the loss in water pressure . The pressure switch can be adjusted when to turn on and off but I don't think that's your problem , sounds like it's the pressure tank.
Plumbing Pro : If you currently have a 20 -40 pressure switch then then the pump is turning on when the pressure drops down too 20 then back off when it reaches 40 . If you replace the switch with a 30 -50 you can increase your water pressure as the system will go up too 50 instead of just 40 and will never go below 30 . But if the pressure tank is bad then the tank will still need replacement .

The pressure tank is a brand new precharged tank and brand new was precharged at 40psi and when we replaced the switch we followed the directions and took it down to 18psi (2psi less than the switch) everything seems to be working fine but the pressure is alot lower than before.

Plumbing Pro : Is your current pressure gauge working , if you turn on a couple of sinks and watch the gauge the pump turns on at 20 psi and off at 40 psi ? Also how many gallon pressure tank did you buy ?

Yes the gauge is working and yes it turns on at 20 and off at 40. So I think after re-reading your first response....if I purchase a 30/50 switch and adjust the pressure on the tank to 28psi I will have more water pressure at the faucet?


The pressure tank is 35 gallon.

Plumbing Pro : Also well pressure tanks come pre set and is best to leave them alone . To the recommended pre set psi . I think you have your psi in the pressure tank down too low and needs to be 2 psi lower then the cut off pressure from the switch . One way you can tell is by going to a couple of faucets and turn them both on at the same time , leave them running . Then go down by the well pressure switch , if you hear the switch clicking on and off every 30 seconds or less then that is the problem . A normal working system the pressure switch should be kicking on every 1-2 minutes when 2 faucets are open at the same time .

Oh ....I think we were confused.....we set the tank 2 psi below to cut on......not 2 psi below the cut off so the pressure on the tank should be 38 psi?

Plumbing Pro : I am sorry the pressure in the tank needs to be set 2 psi lower then the cut off . This is so when the pump turns on the blater compresses and allows for some storage . If your pump is turning off at 40 psi then you might want to get a 30 -50 pressure switch .

No..your good....we weren't confused at your was at the instructions I read with the switch. I think I put way too much thought into it and your answer made me go 'ding ding' ! lol. Okay you straightened that out for me and I Thank you very much. Now I have one other question.... before replacing this tank....we had a 20 gallon pressure tank...and we often ran out of water (we have a very weak well) by purchasing a larger tank will that decrease the frequency of running out of water with the same usage as before? or will it not make any difference?

Plumbing Pro : It's hard to say if you have a week or old pump then that coupled be the problem . No matter the switch or pressure tank the pump still turns on to build pressure , when a pump is old or going bad will often not be able to pump up good or normal pressure . Thank you for choosing Just Answer , merry christmas .

Ok. Thank you very much! Merry Christmas to you too. and have a Healthy and Happy New Year!

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