Pressure Switch (Barbed)/4028P (Replace with 3028P)
Many spa control system with barb hose connection. Pressure Switch (Barbed)-3028BP for Hot Tubs. Used for Old Manual(Non digital reading) Heating Systems. Some of them are Energy Saver 7 or Energy Saver one.
Pressure switch is to detect the water flow through the heater and protect the spa spa pak. If there is no flow or faulty pressure switch you may notice 3 tiny dots flashing , FLOW or FLC (Pressure Switch Closed)