Johnson Controls P70CA 2 Pressure Control 30067439 890 Key Benefits Direct Retrofit Compatibility: Key Benefits Direct Retrofit Compatibility: Specifically designed to convert T 400 series dual temp thermostats to T 4000 series without replacing the original Bakelite back this specific body gasket is compatible with the 813 and 883 (800 Series) as well as the 973 and 983 (900 Series) inverted bucket steam traps Is this control compatible with ammonia systems This specific model features a Close High Open Low switch action with a functional range of 50 to 500 psi and a factory set differential adjustable between 60 and 150 psi