Replaces all Suburban water heater and furnace circuit boards including 520871, 520814, 520820. Will not replace 24VAC model boards. 3 YEAR MANUFACTURERS WARRANTY. DD-17-DSI; NT-12S; NT-12SE; NT-16S; NT-20S; NT-16SE; NT-20SE; NT-24S; NT-24SP; NT-24M; NT-25K; NT-30SP; NT-34S; NT-42T; SF-20; SF-20; SF-20F; SF-25; SF-25F; SF-30; SF-30F; SF-35; SF-35F; SF-42; SF-42F