Tecmark Tridelta (TDI) Stainless Steel Pressure Switch for electric heaters used on spas and hot tubs, 3076. SPDT, Normally Open, 25 Amp water pressure switch has three 1/4"" standard tab wire terminals, Common, NC and NO. Switch has a 1/8"" NPT water connection and pan in stainless steel for durability. Note: 1/8"" NPT threads to attach the water line or to screw into heater tube or header actually measures 3/8"" OD when measured across the threads.
Pressure switches are used on spa, tub and bath heaters to measure the amount of water pressure inside of the heater, as an approximation of water flow. Pressure switches are safety devices intended to prevent heater damage and overheated water hazards. If your pressure switch is causing the heater to shut down, look for causes of low flow in and out of the heater, and remove the spa filter temporarily to improve flow. Pressure switches do fail eventually (which is why sell replacements), but first assume a flow problem, and not a switch problem.
This 3-terminal adjustable Pressure Switch comes factory set but can be adjusted from 2 to 22 psi. Pressure switches do not normally need adjustment after installation, and to avoid heater damage or overheated water, large adjustments should be avoided. 1-2 psi is the correct setting for most spas, tubs and whirlpools. High Altitude locations or spa systems located several feet Below the spa, may need 3-5 psi settings. In extreme cases, an application may call for greater pressure, and this switch goes up to 22 psi, for high flow high pressure systems. Refer to your spa heater manual or heater documentation, for any instructions on heater pressure switch settings.