White-Rodgers 21M51U-843 2 Stage Furnace Control Kit

White-Rodgers 21M51U-843 Universal Two-Stage HSI Furnace Control Kit

Replaces White-Rodgers 50M51-242 and All 50M61-XXX Two-Stage HSI Systems with 80V or 120V Ignitor.

Features:

• 120 VAC Ignitor Output
• 120 VAC Two-Speed Inducer Output
• 120 VAC Humidifier Output
• 120 VAC Electronic Air Cleaner Output
• 120 VAC 3-Speed PSC Circulator Output
• 2-Stage Gas Valve Output
• Fuse Protection 3 Amp
• Furnace Status LED Tri-Color (Green, Red and Amber)
• Heat Fan OFF Delay (Dipswitch Selectable)
• Fan ON Delay for Cooling
• Auto Second Stage Delay (Dipswitch Selectable Mode)
• Historical Fault Retrieval by Pushbutton
• YLO, Y, W1, W2, R, G, C, TWIN Terminals
• Pressure Switch Inputs and Monitoring
• Flash Microprocessor with Non-Volatile Memory
• Flame Current Measurement Points

Specifications:

Electrical Ratings [@ 77°F (25°C)]
Input Voltage: 24 VAC, 60 Hz (Class II transformer required)
Nom. Input Current @ 24 VAC: 530 mA + MV

Relay Load Ratings
Gas Valve Relays: 1.5 amps @ 24 VAC, 60 Hz
Inducer Relays: 2.2 FLA 3.5 LRA @ 120 VAC
Circulator Relays: 14.5 FLA 25.0 LRA @ 120 VAC
Humidifier Load: 1.0 amp max. @ 120 VAC
Electronic Air Cleaner Load: 1.0 amp max. @ 120 VAC
Ignitor Relay: 4.0 amps max. @ 132 VAC, 60 Hz

Flame Current Requirements
Minimum current to insure flame detection: 0.3 DC*
Maximum current for non-detection: 0.1 DC*
Maximum allowable leakage resistance: 100 M ohms
*Measured with a DC microammeter in the flame probe lead

Operating Temperature Range
-40° to 175°F (-40° to 80°C)

Humidity Range
5% to 93% relative humidity (non-condensing)

Timing Specifications (@ 60 Hz)
Flame Failure Response Time: 2.0 sec. max.

Gases Approved: Natural, Manufactured, Mixed, Liquefied Petroleum and LP Gas/Air Mixtures are all approved for use

Kit Includes:

• Ignition Control Module
• Universal 120V Nitride Ignitor Kit 21D64-2
• Installation Instructions and OEM Cross-Reference

Replaces:

White-Rodgers 18M3401,20300001, 20300003, 46M9901, 50M51-242, 50M61-120, 50M61-288, 50M61-289, 50M61-495, 50M61-843, 83L9301, CNT03077, X13650839010