Gas Furnace Service Fundamentals

Service modern residential gas furnaces the way a heating tech does: the 80% AFUE atmospheric vs 90%+ AFUE condensing distinction, the full ignition sequence from thermostat call through flame proving, hot-surface ignitor and flame-rectification diagnostics, pressure-switch and draft-inducer troubleshooting, combustion analysis targets, and high-limit and condensate-system fault tracing. Built from HVAC fundamentals into the combustion basics guide so the service call ends with a safe, correctly-firing furnace.