TSSA Gas Technician 2 (G2) common mistakes
TSSA Gas Technician 2 (G2) · Understand the traps and how to avoid them.
Calculating gas flow or pressure-drop answers with the wrong reference conditions - mixing standard cubic feet with actual cubic feet, or mixing inches of water column with psi - and then reporting the number without units.
Candidates memorize the formulas but drill them without unit tracking, so the arithmetic is right while the basis is wrong; the exam deliberately offers answer options built on the wrong basis (for example, a flow figure computed at 0.60 specific gravity applied to a 0.65 gas).
What to do instead
Write the unit on every line of the calculation and cancel them explicitly; convert to a single basis (inches w.c., cubic feet per hour at the stated standard conditions) before substituting. Before answering, ask which reference basis the question states and reject any distractor computed on a different one. Practice a set of specific-gravity and heating-value conversion problems with units shown.
Treating propane and natural gas as interchangeable when sizing orifices, clocking meter dials, or setting manifold pressure, and applying a natural-gas clocking factor to a propane appliance.
The two gases differ in specific gravity, heating value, and air requirement, but candidates study one fuel's numbers and then apply them to the other; propane's higher heating value per cubic foot and higher specific gravity make flow and derating answers numerically very different.
What to do instead
Build a two-column reference card (natural gas vs. propane: specific gravity, heating value per cubic foot, primary air requirement, typical manifold pressure) and, for each practice question, state which fuel is named before computing. For clocking, confirm the meter dial factor and the gas being metered, and check that the calculated input falls within the appliance rating plate tolerance.
Answering code questions from habit or from what a familiar installer does rather than from the cited clause, and choosing a clearance or distance that is 'close enough' (for example, giving a vent terminal clearance that is a few inches off, or citing the wrong table for a regulator vent distance).
The codebook is large and candidates avoid navigating it under time pressure, so they rely on remembered approximations; many code numbers look similar (inches vs. feet, indoor vs. outdoor, appliance type categories), which makes near-miss distractors effective.
What to do instead
Practice locating the governing clause for each topic in the current edition adopted for the exam (installation code, gas appliance code, and the applicable provincial regulation), and note the exact table or clause number beside each clearance you memorize. When a question quotes a distance, verify whether it is measured to a window, a building opening, a property line, or a regulator vent, because the same appliance can carry several different numbers.
Confusing the roles of the provincial regulation, the adopted CSA standards, and the manufacturer's certified installation instructions, and answering as if one overrides the others in every case.
Candidates learn that 'the code governs' or that 'the manual governs' as a slogan, without learning the hierarchy: the regulation gives legal force to the adopted standards, and the certified instructions apply for the specific appliance, with the more restrictive requirement prevailing where they conflict.
What to do instead
Write out the hierarchy once in your own words and apply it to a handful of conflict scenarios (for example, a manual specifying a smaller clearance than the code minimum). For each practice question, identify which document the question is testing and answer at that level; where the question asks what a technician must do, the correct answer is normally the more restrictive of the code and the certified instructions.
Sizing gas pipe by adding appliance inputs and picking a diameter, without applying the longest-run length, the allowable pressure drop for the system pressure, the fitting and valve equivalent lengths, and the specific gravity and heating-value correction factors.
Candidates treat pipe sizing as a single table lookup; the tables are indexed by pressure drop, material, and gas, and the longest run is measured along the actual route including fittings, so a shortcut produces a plausible but undersized answer.
What to do instead
Work sizing problems in a fixed sequence: list connected loads with their inputs, measure the longest run from the meter or regulator to the farthest appliance, add equivalent length for fittings and valves, select the table for the correct pressure drop and gas, then apply correction factors. Show the sequence on paper for several practice layouts so the order becomes automatic.
Mishandling the bonding and grounding of corrugated stainless steel tubing and yellow-coated copper tubing - omitting the bonding conductor, bonding at the wrong point, or treating the tubing itself as the grounding electrode conductor.
Candidates conflate 'grounding' with 'bonding' and assume any metal gas line is a grounding path; the requirement is to bond the gas piping system to the electrical service grounding system with a properly sized conductor at the specified location, and the tubing must never serve as a grounding electrode conductor.
What to do instead
Learn the bonding requirement as a distinct rule: what is bonded, where the connection is made, the conductor sizing basis, and the prohibition on using gas piping as a grounding conductor. Answer bonding questions by naming the two systems being connected and the point of connection, and reject options that route fault current through the gas tubing.
Sizing combustion air openings by counting only the appliance input in the room and ignoring whether the space is confined or unconfined, the total input of all appliances drawing from the space, and the free area of louvered or screened openings.
Candidates use the two-opening rule as a reflex without first classifying the space by volume-to-input ratio, and they forget that the free area of a grille or louver is less than its nominal size and that the required opening depends on whether air comes from indoors, outdoors at grade, or outdoors from a duct.
What to do instead
Answer in a fixed order: compute the space volume and divide by total input to classify the space; then select the opening method for that classification and the air source; then convert required free area to nominal louver size using the free-area percentage. Practice with a louvered opening and a horizontal duct, since the duct and vertical-duct cases use different sizing bases.
Venting answers that ignore category, appliance type, and vent configuration - for example, applying a natural-draft vent rule to a Category IV condensing appliance, or accepting a horizontal run or termination that the appliance's category and the manufacturer's venting tables do not permit.
Venting is the most configuration-dependent topic on the exam; candidates memorize one set of rules and miss that category (I through IV) determines whether the vent is negative or positive pressure, whether condensate management and slope matter, and which materials and tables apply.
What to do instead
For every venting question, first state the appliance category and the vent system type, then apply the rules for that combination: material, slope, termination location and clearance, and whether the manufacturer's vent length tables govern. Build a category-by-category comparison sheet and use it to answer practice questions until the classification step is automatic.
Skipping or misinterpreting the leak test and purge sequence - using the wrong test pressure or duration for the system volume and pressure, testing with the appliance connected when it should be isolated, or purging into an occupied space.
Candidates compress the commissioning sequence into 'pressurize and watch the gauge' and do not link test pressure and holding time to the system's volume and operating pressure; they also forget that appliances and regulators must be protected or isolated during the test and that purging must be directed to a safe location.
What to do instead
Memorize the test as a set of linked parameters: test medium, test pressure relative to operating pressure, holding time as a function of volume, what is isolated during the test, and the acceptable result. Rehearse the full sequence aloud from meter to appliance, including purge and the leak-detection method, and answer questions by naming each parameter rather than just 'pressure test'.
Diagnosing combustion problems by symptom alone - swapping parts (igniter, flame sensor, gas valve) before measuring - instead of reading flame characteristics, draft, manifold pressure, and carbon monoxide, and distinguishing a combustion-air or venting fault from a control fault.
Field experience rewards part-swapping when it happens to work, and candidates carry that habit into scenario questions; the exam instead rewards a measurement sequence that separates fuel, air, and ignition causes, so symptom-only answers select plausible but non-diagnostic options.
What to do instead
For every troubleshooting scenario, state the measurement sequence first: manifold and supply pressure, combustion air and draft, flame signal and sensor condition, then CO and CO2 readings, and only then component replacement. Practice classifying symptoms (spillage, rollout, delayed ignition, short cycling) into air-side, fuel-side, or control-side causes and name the confirming test for each.