the Nordyne 491226R 8KW Heater Element is often the primary suspect for failure

the 120VAC coil is housed in a NEMA 4X enclosure

Its robust construction supports long-term service in systems exposed to pressure variation and frequent actuation

this is a 208/230V 1-Phase motor

Fault A4 typically indicates a KM-BUS communication issue

Resideo CPR8 Regulator 321702-401 the Nordyne 491226R 8KW HeaterThe Resideo CPR8 Regulator is a critical replacement component for the CPRD8 bypass damper system, engineered to manage pressure fluctuations in constant volume and variable air volume HVAC systems. Designed for heavy duty zoning bypass control, this regulator ensures the barometric damper maintains appropriate static pressure as zone dampers open and close. By utilizing a precise weighted pressure regulator mechanism, the CPR8 prevents excessive air