ensuring no impedance mismatch

it is recommended to inspect and reuse or replace the silicone tubing to ensure a vacuum-tight seal during installation

Precise Pilot Control: Stabilizes pilot pressure to ensure consistent ignition and reliable flame proving

or the thermocouple failing to generate the 20-30mv required to hold the safety valve open

As a manual reset spill switch

Johnson Controls A28AA-37 Temperature Control Refrigerant ensuring no impedance mismatchTemperature Control, Two Stage, 2 SPDT Switch Action, 120 208 240 277 Vac, 60 140 Degree Setpoint Range, 5 Degree Differential Each Stage, 2 7 Degree Adjustable Differential Between Stages, 3 8" x 4" Bulb, 6' Capillary Length, Knob Range Adjuster A28AA 37 is identical to A28AA 37C