... air pressure switch for fireplace and hot water heater 2,global safety approvals 3,pressures are adjustable 4,EC approval GPS100 series pressure ... used to sense positive,negative or differential air pressure.A sensitive high reliability snap action switch ... pressure allowed:4000pacontact arrangement:SPDT,SPST-NO,SPST-NCoperating temperature:-40~90°C GPS100 air pressure switch for fireplace and hot water ...