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How to Adjust a Spa Pressure Switch

Mary Lougee

A spa pressure switch operates underwater pressure to turn the heater on and off. If there is not enough water in the spa or insufficient flow of water, the pressure switch turns the water heater off to prevent overheating. Adjusting the pressure switch to a lower psi enables the switch to turn on quicker and supply extra heat to the water in a spa. If the red light blinks on and off quickly or if the pump is on the low speed and the red light is not illuminated, you need to lower the psi on the switch.

  1. Turn the electrical breaker to the spa off in the breaker box.

  2. Insert a screwdriver into each screw in the spa pack cover. Turn each screw counterclockwise to loosen and remove them. Pull the cover straight off the spa and set it aside.

  3. Turn the pressure switch adjustment wheel counterclockwise to break the spot weld on the bottom. Pull the two yellow wires off the pressure switch. The pressure switch is a metal cylindrical switch with a flat metal plate next to it with a scale of one to five psi marked on it. The round top is the pressure adjustment wheel.

  4. Place each probe of a continuity tester on each of the two areas where you removed the yellow wires from the switch. The continuity tester should not light up to indicate that the switch is open. If the light illuminates on the tester, turn the adjustment wheel clockwise until the light goes out. This action opens the switch and does not allow power to flow through it.

  5. Slowly turn the adjustment wheel counterclockwise until the switch closes and the tester light illuminates. The pressure switch is closed and power will flow through the circuit now.

  6. Turn the adjustment wheel one-half revolution clockwise past the point when the tester illuminated.

  7. Replace the two yellow wires on the switch and place the metal cover on the spa pack box. Insert the screws into the holes and turn them clockwise to tighten each one.

  8. Turn the power breaker to the spa on.