Hello.

I would like to add a new pressure switch to an existing water pump (115V) that has
an integrated pressure switch built into it.

The current pump has an integrated 30/50 pressure switch. I bought a new
pressure switch that is adjustable. Cut-in and cut-out pressures can be
adjusted.

So my question is how do I wire this new pressure switch so that the one that
is built into the pump is bypassed? Currently I have 4 terminals on the old
pressure switch and all 4 are in use (2 white and 2 black). I am assuming that
I would not use all 4 terminals if I bypass it.

Thanks again for your advice!

I have attached manuals below:

Water pump (page 15 is the wiring page)
http://www.grainger.com/ec/pdf/Dayto...-Pump-OIPM.pdf

New adjustable pressure switch
http://s3.supplyhouse.com/manuals/13..._PROD_FILE.pdf

 

Most well pumps that I am familiar with are all 240 volts. The white might be a 120 volt hot leg that was not remarked as a hot.

 

From the literature it appears the switch is external, and could easily be replaced with a like design adjustable switch.

 

Page 15 discusses dual voltage motors. Are you sure yours is not running on 240vac ?

They more than likely have connected both motor lines to the one side of the switch and the line to the other side. If the motor is in 120v mode then the pressure switch breaks both hot and neutral.

Your switch should wire identically to the one attached to the motor. You may have to remove the old pressure switch and install a junction box so that the motor wiring will reach your new pressure switch.

 

Simply connect "jumpers" across the terminals of the existing pressure control. If the contacts are visible , "Jump" the terminals of each contact so there is a closed-path to the motor when the existing contacts are open. If contact closure switches a White "Line" wire to a White "Load" wire , then jump these terminals. Ditto for a Black to Black contact-closure.