White-Rodgers 21V51U-843 universal integrated furnace control runs 2-stage gas furnaces with two-speed inducer and two-stage valve outputs. It provides variable-speed circulator output for ECM motors.
Dipswitches set heat fan delays and second-stage timing for OEM matching. Pushbutton fault history retrieval aids service. Package includes 21D64-2 silicon nitride ignitor kit, module and wiring harness.
21V51U-843 highlights
Universal 2-stage replacement
Covers two-speed inducer and two-stage gas valve applications by dipswitch.
ECM circulator output
Drives electronically commutated blower motors.
Pushbutton fault history
Recalls past faults without extra tools.
Ignitor kit included
Ships with 21D64-2 ignitor, module and harness for install.
21V51U-843 specifications
Delays: Heat fan off delay, cooling fan on delay, auto second-stage delay
Outputs: Two-speed inducer output, two-stage gas valve output
