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The Gas Heating Installation exam has 100 questions and runs 2 hours 30 minutes.
These 10 free Gas Heating Installation questions are organized by exam domain, so you can see how each part of the Gas Heating (Air) Installation blueprint is tested. Reveal the answer and explanation under each question.
The startup record for a natural-gas furnace lists 100,000 Btu/h nameplate input and 90% AFUE. With the burners running continuously and every other gas appliance off, a 2-ft³ meter dial makes one revolution in 96 seconds. The utility's heating value is 1,080 Btu/ft³, on the same volume basis as the meter reading. What measured fuel-input rate belongs on the record?
Correct answer: B - 81,000 Btu/h
A furnace cycles on its high-temperature limit before satisfying the thermostat. Just before the limit opens, representative return and supply temperatures are 72°F and 150°F. The nameplate permits a 35-65°F temperature rise. Metered gas input and manifold pressure meet the manufacturer’s specifications. Where should the installer focus the corrective work?
Correct answer: A - Restore adequate heating airflow, then recheck the temperature rise.
A thermostat serves a furnace and air conditioner with separate 24-V transformers. Its two-transformer diagram assigns heating hot to R, cooling hot to Rc, and cooling common to C. These wires are correctly landed, but the factory R-Rc jumper is still in place. Both power sources have been disconnected. To complete the wiring, the installer should:
Correct answer: A - Remove the jumper; keep R, Rc, and C as wired.
Following a furnace replacement, air is drawn into a flexible return-duct connection in the crawlspace. The insulated, nonmetallic duct’s outer jacket is tightly taped to a beaded metal collar, but its inner core is loose. Which repair restores the intended joint?
Correct answer: A - Seal and clamp the core past the bead; restore insulation and reseal the jacket.
A condensing furnace is listed for a one-pipe installation. Its approved exhaust operates under positive pressure, while combustion air enters from the equipment room. The room has the required combustion-air provisions. How should the installation be classified?
Correct answer: D - Category IV and non-direct vent, with indoor combustion air.
After an approved filter with greater pressure drop is fitted, a constant-airflow ECM increases its speed while holding the commanded airflow. External static pressure and motor operation remain within the furnace manufacturer’s limits. The installer has not changed the airflow command. How should this behavior be interpreted?
Correct answer: C - Expected compensation: the motor is maintaining airflow against greater resistance.
A furnace’s pressure-switch data specify closure at −0.70 inch w.c. as draft increases and reopening at −0.55 inch w.c. as draft weakens. The switch is open at rest. After closing during startup, it remains closed as the measured differential changes from −0.85 to −0.62 inch w.c. How should the retained closed state be assessed?
Correct answer: B - Remaining closed at −0.62 agrees with the specified reopening differential.
A furnace replacement must provide 50,000-70,000 Btu/h of heating output under the approved design. The matched cooling system needs at least 1,200 CFM at 0.60 inch w.c. external static pressure. The ratings below apply at those conditions; all four models fit and are compatible with the fuel and vent system. Which model satisfies both performance requirements?
Correct answer: C - 80,000 Btu/h input, 64,000 Btu/h output, and 1,300 CFM.
An installer proposes a 6-inch vent for a 100,000-Btu/h, single-stage, fan-assisted Category I furnace with a 4-inch flue collar. For the actual 8-foot height and 2-foot lateral, the applicable table lists FAN input ranges of 59,000-108,000 Btu/h for 4 inches, 83,000-176,000 for 5 inches, and 121,000-261,000 for 6 inches. The proposed Type B vent and same-size single-wall connector meet the table’s other conditions. Which review comment is sound?
Correct answer: D - A 4-inch vent qualifies; the 6-inch vent fails the minimum-input requirement.
A household carbon monoxide alarm sounds during a furnace startup check, and an occupant reports a headache. The burner flames appear stable. What takes priority?
Correct answer: D - Move everyone outside, then call emergency responders from a safe location.
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