Red Seal Gasfitter Class B cheat sheet
Red Seal Gasfitter Class B · Keep the key ideas within reach.
Work planning and measurement
Confirm the current approved documents and actual equipment identity.
Isolate and verify relevant energy sources, including stored energy.
Record pressure reference, test point and operating load.
Select instrument range and resolution for the measurement.
Input rate = volume flow × heating value on matching bases.
Efficiency = useful output / input.
Use units to detect an inverted conversion or missing factor.
Fuel delivery and components
Size each section for its downstream loads using the applicable method.
Use the table and assumptions for the actual fuel and piping system.
Consider fitting and route resistance, not straight length alone.
Match materials, ratings and approvals as well as thread size.
A cracked flare or kinked tube needs approved correction.
Check regulator flow direction, vent condition and specified operation.
Compare no-flow behaviour with performance under connected load.
Combustion and venting
Complete methane combustion principally forms carbon dioxide and water.
Total air and local mixing both influence combustion completeness.
Flame colour alone cannot quantify carbon monoxide.
Venting depends on driving pressure, resistance and building conditions.
Distinguish combustion air from downstream dilution air.
Use the approved vent system for pressure, temperature and condensate.
Effective free area = gross opening × stated free-area fraction.
Controls and circuits
Trace demand, proving, purge, ignition, run and shutdown in order.
A normally open symbol describes the specified reference state.
Voltage is measured across points; inline current is measured in the path.
Resistance testing normally requires isolation and verification.
Thermostat demand does not prove flame.
Flame-rectification grounding forms part of the sensing circuit.
A permanent jumper is not a repair for a protective control.
Commissioning and service
A successful ignition is not a complete commissioning test.
Distinguish piping pressure tests, connection leak checks and operating tests.
Account for other loads when measuring input through a shared meter.
Heat transfer depends on flow and temperature rise.
Investigate the cause of repeated safety trips.
Verify actual shutdown and the affected post-repair safety functions.
Document restrictions and leave decommissioned branches safely identified.