Diagnostic inspection
We start with a visual inspection of the firebox, burner assembly, glass and gasket condition, and venting system, looking for soot buildup, lifting flames, cracked components, and signs of incomplete combustion that may not be visible when the unit is off. A manometer measures gas pressure at the valve and burner to verify it matches manufacturer specifications. Low pressure causes weak flames, high pressure creates safety hazards. If pressure is off, we adjust the regulator. This is one of the few problems that looks like a failed part but is actually an easy fix, so we always test it before ordering a replacement. A combustion analyzer tells us whether the unit is burning clean, because incomplete combustion is invisible to the eye but shows up instantly on the meter.