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Pressure Switch HELP

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Troubleshooting Pressure Switches

A pressure switch will allow power to pass through it as long as there is a measurable amount of water pressure in the plumbing to which it is connected. This pressure is created whenever the pump is running as long as there is water on the line and you do not have an airlock. 

If you see that you have good water flow and your heater will not operate, check to see that the thermostat makes a "click" noise. If you hear the "click" and the contractor will not close, check (with your voltmeter) to see that the power is found at both terminals on the thermostat. Disconnect the thermostat wire leading to pressure switch before checking the thermostat voltage. Then, check for power at the coil where the wire from the pressure switch meets it. (Double check as to what coil voltage should be.)

If you have proper voltage at all three points, the pressure switch is not at fault. If you do not find power at any of the three points, your air switch may be at fault or you may be expecting the heater to operate when it is not supposed to be in the first place.

If you find power on one side of the thermostat and not the other with the thermostat turned all the way up, the thermostat is either defective, out of calibration, or the spa water is already hot. If you find power at both terminals on the thermostat and none on the contactor coil, the pressure switch is either out of calibration or is not functioning and must be replaced.

On the other hand, if you cannot get the heater to shut ‘off while the valves are open and the pump is running "dry", then the switch is either broken or frozen shut and must be replaced, or the contacts of the heater relay are welded closed.

To replace it, first shut off the power and then remove the two wires going to it. If you have service valves to the equipment pack, shut them off. If not, and the pressure switch is of the type that has a barbed fitting and a hose connecting it to the heater, have the new switch close by and proceed as directed in the next paragraph. If you haven’t any valves and the switch screws directly into the heater manifold, you will have to drain the spa in order to change the switch.

If your switch screws directly into the heater manifold and you have service valves, you might want to drain water from at least the heater before removing the switch. Otherwise, depending on how the heater is oriented, you may get water inside the control box and on your wiring.

Once removed, we suggest you replace the switch with one that has stainless steel threads. (The one you removed may have plastic threads as they are less expensive.) To install a plastic thread switch properly with a mass of wires around may prove difficult if not impossible as the threads are prone to cross-threading if it doesn't go in perfectly straight. This will result in a leak, either now or later. A stainless steel pressure switch is easier to install with a little PTFE applied to the threads.

In either case, once the new switch is installed, re-attach the two wires and BE SURE TO OPEN THE SERVICE VALVES. Now turn the power back on.

Balboa heater