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Piping & Tubing: The piping and tubing sizing tables in the B149.1 Code:
Answer: are guidelines for ensuring that the maximum allowed pressure drop is not exceeded
Other choices: are interchangeable · all include an allowance for a reasonable number of fittings · are all based on a pressure drop of 50%
The sizing tables give pipe sizes that keep pressure drop within the allowed limit for a given length and load. They're a tool for meeting the pressure-drop rule.
Piping & Tubing: How shall underground piping or tubing shall be tested?
Answer: In accordance with the requirements established in the B149.1 Gas Code.
Other choices: In accordance with the appliance manufacturer’s installation instructions. · In accordance with the requirements established by the gas distributor. · All underground gas piping shall be tested to 100 psi (700 kPa) for 3 hours.
Underground piping is tested to the requirements in the B149.1 code, not to manufacturer or distributor rules.
Electricity: If a co-worker is suffering a shock from an electrical circuit and cannot let go of the circuit, the first action to take is:
Answer: Disconnect the power to the electrical circuit.
Other choices: Call the emergency response phone number. · Give the co-worker a quick push to free him or her from the circuit. · Grab the closest object and shove the person away from the circuit.
Kill the power first. If you touch the victim while the circuit is live, you become part of the circuit too.
Electricity: The amperage reading in a series circuit will be:
Answer: The same in all parts of the circuit.
Other choices: Supply amperage. · Different after each load in the circuit. · Increased if one load is not working.
A series circuit has only one path, so the current is the same everywhere in it.
Controls: A room temperature thermostat used on most residential furnaces will be found in which one of the following circuits?
Answer: On-Off Operating control circuit
Other choices: Safety control circuit · Auxiliary control circuit · Proportioning operating control circuit
A standard residential thermostat simply turns the burner on and off, so it's an on-off operating control.
Controls: What is the purpose of a high temperature limit switch found on gas fired forced air appliances?
Answer: To shut off the burner in the event of overheating.
Other choices: To prevent unsafe supply air temperatures on start up. · To control the air flow rate over the heat exchanger. · To operate the fan motor.
The high limit shuts the burner off if the heat exchanger overheats, for example from a blocked filter or failed blower.
Building Systems: A properly sized outdoor air intake is designed to supply:
Answer: Dilution air and combustion air requirements.
Other choices: Only combustion air requirements. · Only draft dilution air requirements. · All the air supply needs for the building.
A correctly sized outdoor air opening supplies both combustion air and dilution air for the draft control.
Building Systems: What is the minimum size of the mesh required on an air intake grille?
Answer: 1/4" (6 mm)
Other choices: 3/32 " (2 mm) · 1/8" (3 mm) · 1/2" (12 mm)
Mesh smaller than 1/4" (6 mm) clogs too easily, so 1/4" is the minimum.
Domestic Appliances: What is the maximum allowed length of a corrugated flexible connector permitted for use on a gas range?
Answer: 6 feet (1.8m)
Other choices: 2 feet (600mm) · 10 feet (3m) · 12 feet (3.6m)
A flexible connector on a gas range can be up to 6 ft (1.8 m) long.
Domestic Appliances: What type of protection does a range require if it is certified for zero side clearance from combustible material?
Answer: No protection is required.
Other choices: 22 MSG (0.68 mm) sheet metal applied directly to the combustible material. · 28 MSG (0.3 mm) sheet metal spaced out 0.25 inch (6 mm) · 1/4 inch (0.6 mm) insulating millboard
If the range is certified for zero side clearance, no extra protection is needed. Follow the rating plate.
Meters, Regs & Valves: Which of the following is correct concerning the proper handling of domestic gas meters?
Answer: Meters shall be transported securely in an upright position with the openings capped.
Other choices: Meters shall be filled with water while being transported. · Meter inlet and outlet connections shall be left uncapped when being transported. · Meters shall be secured horizontally while being transported.
Meters are delicate. Transport them upright, secured, with the openings capped to keep dirt and water out.
Meters, Regs & Valves: Which component is the measuring element in a pressure reducing regulator?
Answer: The diaphragm
Other choices: The spring · The valve and valve seat · The vent outlet
The diaphragm is the measuring element. It senses outlet pressure and moves the valve.
Dom. Gas Refrigeration: A gas-fired refrigerator should be serviced and cleaned:
Answer: At least once a year or as recommended by the manufacturer.
Other choices: Only when it fails to operate or fails to provide adequate refrigeration. · Once every two years. · At least three times a year or as recommended by the manufacturer.
Service and clean once a year, or as the manufacturer recommends, to keep the flue and burner clean.
Dom. Gas Refrigeration: Which one of the following statements is correct concerning propane and natural gas refrigerators?
Answer: The orifice on a propane refrigerator is smaller than on a natural gas refrigerator.
Other choices: A propane burner is located at the top of the refrigerator and a natural gas burner Is located at the bottom. · A natural gas burner is located at the top of the refrigerator and a propane burner Is located at the bottom. · The orifice on a propane refrigerator is larger than on a natural gas refrigerator.
Propane has more energy per cubic foot than natural gas, so it needs a smaller orifice for the same input.
Conversion Burners: By definition, a forced draft burner has a blower that produces sufficient pressure to overcome the resistance of the:
Answer: Burner and the appliance.
Other choices: Burner only. · Burner and the appliance downdraft. · Power venter.
A forced draft burner's blower is strong enough to push through both the burner and the appliance's heat exchanger.
Conversion Burners: To convert a revertible flue furnace with a natural draft burner, how far above the burner port does the centre line of the flue outlet have to be?
Answer: At least 12 inches.
Other choices: At least 6 inches. · At least 24 inches. · A revertible flue furnace can never be converted using a natural draft burner.
The flue outlet's centre line must be at least 12" above the burner port.
Code reference: Clause 7.8.1 a in B149.1
Water Heaters: What component of a storage water heaters directs the incoming cold water to the lower part of the tank?
Answer: a dip tube.
Other choices: an anode. · a temperature and pressure relief device. · a Unitrol gas valve.
The dip tube carries cold incoming water to the bottom of the tank so it doesn't mix with the hot water at the top outlet.
Water Heaters: A standard underfired storage type domestic hot water heater is equipped with:
Answer: temperature and pressure relief valve, dip tube, and anode.
Other choices: pump, pump control, flow switch, temperature and pressure relief valve, and high temperature limit control. · temperature and pressure relief valve, dip tube, and mixing valve. · Unitrol, power venter, and low water cut-off device
A standard tank heater has a T&P valve, a dip tube and an anode.
Warm Air Systems: Which profile of gas furnace has the fan and heat exchanger at each end and the supply and return plenums are both on top?
Answer: Lo-Boy
Other choices: Hi-Boy · Horizontal · Counterflow
A lo-boy is short and long. The blower and heat exchanger sit side by side, with both plenums on top.
Warm Air Systems: By definition, an 85% efficient furnace that has a non-positive vent pressure is in:
Answer: Category I
Other choices: Category II · Category III · Category IV
An 85% furnace with non-positive vent pressure is Category I. It doesn't condense in the vent.
Hydronic Heat: The system water within a cast iron hot water boiler flows from section to section within the boiler through:
Answer: Push nipples.
Other choices: Water flow nipples. · Inlet openings. · Outlet openings.
Cast iron sections are joined by push nipples, which let water flow from section to section.
Hydronic Heat: Low water cut-off valves are used to shut off:
Answer: Fuel when the water is low.
Other choices: Water when the water level is low. · Air when the water level is low. · Feedwater when the boiler is full.
A low water cut-off shuts off the fuel if the boiler water level gets too low.
Space Heating: A room heater may only be installed in a bathroom if it is a _______ type?
Answer: Direct vent
Other choices: Direct fired · Forced draft · Natural draft
Only a direct vent room heater can go in a bathroom. It's sealed from the room air.
Code reference: Clause 7.24.1
Space Heating: Which of the following wall furnaces can be operated during a power outage?
Answer: A wall heater that provides gravity heat and is equipped with a millivolt gas valve and operating circuit
Other choices: A wall heater that provides gravity heat and is equipped with a 24V gas valve and operating circuit · A counterflow wall furnace equipped with a battery back-up thermostat · No wall furnaces can operate during a power outage
A gravity wall heater with a millivolt valve makes its own power from the pilot, so it works without electricity.
Venting: Which one of the following statements concerning thermal draft is correct?
Answer: Draft intensity in a chimney increases as the temperature of flue gases increase.
Other choices: Changing the air supply to a furnace room will have no effect on a natural draft vented furnace. · A dirty heat exchanger will have no effect on draft. · The height of a chimney has no effect on draft.
Hotter flue gas is lighter compared with outdoor air, so it rises faster and draft gets stronger.
Venting: A vent system that can only be used with an appliance that the vent system has been tested and approved with is called a(n):
Answer: Special venting system.
Other choices: Induced draft vent. · Forced draft vent. · Natural draft venting system.
A special venting system is certified only for use with specific appliances.
Forced Air: The cleaning frequency on a new E.A.C. installation should be:
Answer: Weekly for the first month, then monthly
Other choices: Once in the summer and once in the winter · Every day · Four times a year
Clean a new EAC weekly for the first month (new homes are dusty), then monthly.
Air Systems: Convert 68° F to Celsius
Answer: 20° C
Other choices: 5° C · 15° C · 32° C
°C = (°F − 32) × 5/9 = (68 − 32) × 5/9 = 20°C.
Air Systems: What instrument is used to determine air restrictions in the furnace duct work?
Answer: Either a magnehelic gauge or an incline manometer
Other choices: Magnehelic gauge · Incline manometer · Sling psychrometer
Duct static pressure is read with a magnehelic gauge or an inclined manometer.
Meters, Regs & Valves: When should an internal relief valve on a regulator open?
Answer: When there is excessive pressure in the downstream piping system.
Other choices: When the outlet pressure falls below the regulator inlet set point. · When the regulator outlet pressure is more than ten times the normal set point. · When the inlet pressure falls below the outlet pressure set point.
The relief opens when downstream pressure rises above what's safe.