Resideo R24AA3004 Heat Sequencer 321894 708 Contractors often select the normally Contractors often select the normally closed 120V solenoid valve configuration for systems requiring fail safe shutoff protection during power loss or maintenance service Standard replacement mandates a new gasket to ensure an airtight seal between the collector box and the inducer housing to prevent flue gas leakage With a 25 Amp resistive contact rating and a 14 Amp inductive contact rating at 120Vac solid state PTC (Positive Temperature Coefficient) heater provides precise control over the timing of heating banks to prevent circuit overload and ensure consistent discharge air temperatures