During the Heating Safety inspection the technician should test all exposed gas piping in the mechanical room for gas leaks. Leaks are typically found at the flare fittings, mechanical joints and at regulators. Below are two common techniques to test for gas leaks.
Allow the tester to warm up. Trace all mechanical joints slowly with probe, watching for the LEDs to indicate a leak.
Soak all mechanical joints with testing solution and look for air bubbles gas leakage out of the part.