{"product_id":"emerson-21m51-843-two-stage-integrated-furnace-control-board","title":"EMERSON 21M51-843 Two-Stage Integrated Furnace Control Board","description":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eThis product may contain shelf wear, have minor cosmetic imperfections, or have been tested. All our certified pre-owned products are backed by our return policy. We offer free shipping on all items. Please contact us for discounts or if you have any questions. We look forward to doing business with you!\u003c\/em\u003e\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003e· Two-stage integrated furnace control with Hot Surface Ignition (HSI) system compatibility\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e· Replaces White-Rodgers 50M51-242 and all 50M61 series controls · Input voltage: 120 VAC, 60 Hz with Class II transformer (24 VAC control voltage) · Max input current at 24 VAC: 530–800 mA plus gas valve · Controls 2-stage gas valve outputs (1.5 amps @ 24 VAC) · 120 VAC outputs for two-speed inducer blower, humidifier, electronic air cleaner, and 3-speed PSC circulator motor · Fuse-protected with a 3-amp fuse · Heat fan ON delay (approximately 90\/120\/150\/180 seconds, dip-switch selectable) · Cool fan ON delay: 5 seconds; cool fan OFF delay: 60 seconds · Heat fan OFF delay: dip-switch selectable, typically around 45 seconds · Auto second stage delay and fault history retrieval via pushbutton · Pressure switch inputs with monitoring and flame current sensing for safety control · Flash microprocessor with non-volatile memory for timing control · Tri-color furnace status LED (green, red, amber) for diagnostic feedback · Electronic air cleaner and humidifier outputs included · Compatible with HotRod™ universal ignitor kit 21D64-2 (ceramic diameter 0.394\") · Designed for use with two-stage gas furnaces requiring robust ignition and blower control functions\u003c\/p\u003e","brand":"Emerson","offers":[{"title":"Default Title","offer_id":43673077710957,"sku":"13957","price":240.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0637\/2419\/1853\/files\/s-l800_d5f99c55-bfcc-42d7-be48-58d99b687388.jpg?v=1763347311","url":"https:\/\/willardshvacsupply.com\/products\/emerson-21m51-843-two-stage-integrated-furnace-control-board","provider":"Willard's HVAC Supply","version":"1.0","type":"link"}