This is a replacement sail switch for select Suburban furnaces. The sail switch is an air proving device. It is a safety component that will not let ignition occur until it sees 75% of the motor’s rpm’s.
For NT-24SP, NT-30SP, NT-34SP, NT-40 you will need 520839 Module Board Wiring Harness. 12 VDC. Local Flame. Works with all SF and NT Furnace models. Replaces Suburban 520820 & 232613. Cover is not included.
Compatible with the following Suburban Furnaces with Single Sense Electrodes NT-12S, NT-12SE, NT-16S, NT-16SE, NT-16SQ, NT-16SEQ, NT-20S, NT-20SE, NT-20SQ, NT-20SEQ This electrode will not replace dual-sense electrodes on the above furnaces.