Pressure Switch - Tecmark 3902 3903 and 34-0178

Is also being used in Balboa systems under the part number, shown on the sticker: 36142 (2psi) and the Tecmark code is 3903.

If your panel is showing a flow error and with Gecko that means x3 flashing dots, replacing this switch is definitely the first port of call after you have checked that your filters are clear, the spa has enough water, there are no obstructions to the flow of water through the heater or that the pumps are actually moving the water (air lock)

Easy to fit - this switch can sometimes be found inside the spa pack and therefore very close to the circuit board. On this occasion you should drain the spa to prevent water going onto the circuit board - even with gate valves you can have a spray of water because a build up of water pressure - you have been warned.....drain the spa !