TSSA Gas Technician 1 (G1) flashcards
TSSA Gas Technician 1 (G1) · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Methane combustion equation
- CH4 + 2O2 -> CO2 + 2H2O. One volume of methane consumes two volumes of oxygen, which is about ten volumes of air because air is roughly 21 percent oxygen.
- Propane combustion equation
- C3H8 + 5O2 -> 3CO2 + 4H2O. Each volume of propane vapour needs five volumes of oxygen, or roughly 24 volumes of air, for complete combustion.
- Carbon monoxide hazard
- CO is a colourless, odourless, toxic gas produced by incomplete combustion. It binds haemoglobin far more strongly than oxygen, so low concentrations can cause illness or death.
- Relative density of gases
- Specific gravity relative to air equals 1.0. Natural gas is about 0.6 and rises, while propane is about 1.5 and butane about 2.0, so both LP gases pool in low areas.
- Flammable limits natural gas
- Natural gas burns only when its concentration in air is roughly between 4 and 15 percent by volume. Below or above that band the mixture is too lean or too rich to ignite.
- Pressure unit conversions
- One psi equals 27.68 inches of water column and 2.31 feet of water. One inch of water column equals 0.0361 psi, or about 249 pascals.
- Combined gas law
- P1V1/T1 = P2V2/T2 using absolute pressure and absolute temperature in kelvin. Volume falls as pressure rises and rises as temperature increases, affecting meter clocking.
- Ontario gas regulation
- The Gas Safety Act and O. Reg. 212/01 govern gaseous fuels in Ontario, supported by CSA B149.1 for natural gas and propane installation and B149.2 for propane storage.
- G1 technician scope
- A G1 certificate holder may work on any size and type of gas appliance and may supervise G2 and G3 holders, with authority over the full range of gas equipment.
- G2 input limit
- A G2 technician is limited to appliances with an input of 400,000 Btu/h or less. The limit applies to the appliance rating, not to the building size.
- Leak test requirement
- Every gas installation must be pressure tested before being placed in service, using the code-specified medium, pressure and duration, with no pressure drop accepted as a pass.
- Manufacturer instructions precedence
- Certified manufacturer instructions govern installation details, and where they conflict with the code on a specific point, the more restrictive requirement applies unless the authority rules otherwise.
- Gas input formula
- Input in Btu/h equals gas rate in cubic feet per hour multiplied by the heating value in Btu per cubic foot. Compare the result with the appliance rating plate.
- Meter clocking formula
- Cubic feet per hour equals cubic feet metered times 3600 divided by the seconds of the test. Two cubic feet in 60 seconds equals 120 cubic feet per hour.
- Temperature rise measurement
- Temperature rise is supply-air temperature minus return-air temperature after steady operation. A rise above the rating plate range indicates restricted airflow or wrong blower speed.
- Manifold pressure setting
- Manifold pressure is adjusted to the rating plate value with the appliance firing. Natural gas is commonly 3.5 inches of water column and propane 10 to 11 inches.
- Flame appearance diagnosis
- A sharp blue flame with a defined inner cone shows good primary aeration. Yellow tipping, lifting or a lazy flame suggests wrong orifice, low pressure or dirty burner ports.
- Longest-run pipe sizing
- Measure from the meter to the farthest outlet, total connected load in cubic feet per hour, then select pipe size from the capacity table for that material and pressure drop.
- Pipe thread sealant rule
- Approved sealant is applied to male threads only, leaving the first two threads bare. Pipe must be reamed and free of cuttings before assembly to protect downstream controls.
- Sediment trap requirement
- A drip leg or sediment trap is installed ahead of appliance controls so dirt and pipe scale settle out rather than fouling the gas valve or orifice.
- Regulator vent location
- A regulator vent must terminate outdoors, protected from rain, snow and blockage, and away from windows, doors and combustion air intakes to prevent gas entry.
- Appliance shutoff valve
- Each appliance requires a manual shutoff valve in the same room and within reach, plus an approved union or connector, so the appliance can be isolated for service.
- Vent connector slope
- Vent connectors slope upward toward the chimney at a minimum of one quarter inch per foot of run, are as short and direct as possible, and are supported along the run.
- Draft hood function
- A draft hood dilutes flue gases with room air, relieves stack effect and downdraft, and stabilises draft. It must never be blocked, modified or removed from the appliance.
- Combustion air openings
- A confined space needs two permanent openings, one near the top and one near the bottom, sized per code, often one square inch free area per 1000 Btu/h for inside air.
- Condensing appliance venting
- Category IV appliances vent under positive pressure and produce acidic condensate, so they use rated plastic vent pipe and a trapped drain, often with a neutraliser.
- Vent termination height
- A naturally vented appliance vent typically terminates at least one foot above the roof within ten feet horizontally, and two feet above a ridge within ten feet.
- 24 volt thermostat terminals
- R supplies 24 volts hot, C is common, W calls for heat, G runs the indoor blower and Y calls for cooling. Heating begins when the thermostat closes R to W.
- Ignition sequence order
- The thermostat calls for heat, the draft blower proves through the pressure switch, the igniter energises, the gas valve opens, flame is proven, then the blower starts after a delay.
- Flame sensor signal
- The flame sensor uses flame rectification and must return a small DC microamp signal, often one microamp or more. A dirty rod or poor ground causes lockout.
- Rollout switch purpose
- A rollout switch is a manual-reset safety that trips when flame escapes the burner box, usually from a blocked flue, dirty burners or a cracked heat exchanger.
- High-limit switch function
- The high-limit switch opens the control circuit when the appliance overheats, commonly from low airflow. It is a safety device and must never be bypassed or defeated.