HVAC Gas Heat Certification Exam Questions and Answers, Exams of Electrical and Electronics Engineering

Download HVAC Gas Heat Certification Exam Questions and Answers and more Exams Electrical and Electronics Engineering in PDF only on Docsity! HVAC Gas Heat certification exam Questions And Answers A gas furnace is to be installed in a garage. The national standards require that the burners and ignition sources must be located ______ above the floor - correct answer 18 inches A good description of how a bi-metal fan switch operates the blower motor on a gas furnace is - correct answer Temperature on- temperature off Redundant gas valves used on gas furnaces have - correct answer Dual gas shut off seats Burning one cubic foot of liquefied petroleum gas completely will produce approximately ______ BTUs - correct answer 2000 - 2500 LP gas has a specific gravity of - correct answer 1.5 - 2.0 What is the purpose of a spoiler screw located on a burner, or adjustable-shutters? - correct answer Mix primary air and gas Furnace limit switches are wired in series with the - correct answer Gas valve HVAC Gas Heat certification exam Questions And Answers A technician is using an extension ladder to work on roof top unit. The top of the ladder should extend _____ beyond the support point - correct answer 3 feet A technician determines that a natural gas furnace has a defective heat exchanger. The technician should - correct answer Inform the homeowner and turn the gas off A natural gas furnace usually requires _____ gas pressure at the manifold and burners - correct answer 3.5 in. W.C. The vent system for a condensing furnace is classified as ____ by the National Field Gas Code. - correct answer Category IV Type B vent pipe must be kept at least _____ from combustible materials - correct answer One inch Typical condensing furnaces have an AFUE rating of at least - correct answer 90% HVAC Gas Heat certification exam Questions And Answers The ignition temperature of Natural Gas is - correct answer 1100°F - 1200°F Air that is mixes with Natural Gas in the burner is called - correct answer Primary air What is the volume of flue gas produced from a 60,000 BTU/h Category I fan assisted Natural Gas furnace operating with 50% excess air? - correct answer 600 cu ft. The purpose of a flue baffle is to - correct answer Increase heat exchange The LP gas pressure supplied to the appliance gas valve should be - correct answer 11 - 13 in. W.C. An installed gas furnace should have a minimum of - correct answer 12 Which conditions listed below would cause the temperature limit safety switch to shut off the burner - correct answer Fan motor failure HVAC Gas Heat certification exam Questions And Answers The cut off plate is a component of the - correct answer Blower housing A "spud" or burner orifice - correct answer Meters gas to the burner A good thermocouple should read approximately ____ on a D.C. meter - correct answer 30 millivolta Liquefied petroleum, (LP) gases are - correct answer Propane and butane Fan time/temperature delay switches are used on gas furnaces to - correct answer Allow the heat exchanger to warm up What instrument would a technician use to measure return airflow to a furnace - correct answer Anemometer A furnace with a hot surface igniter will not light. Before changing the igniter the technician should - correct answer Check voltage to igniter HVAC Gas Heat certification exam Questions And Answers A technician starts a standing pilot furnace and notices on main ignition the flames "roll out". The technician suspects - correct answer Low gas pressure A technician servicing an LP gas furnace notices a tag stating it was converted from natural gas. He finds large amount of soot I'm the heat exchanger. What could be the cause of this soot - correct answer Orifice, (spud) too large A customer tells a technician that his six month old furnace stops heating before the residence is warm. This happens only on very cold nights. The technician suspects - correct answer Incorrect heat anticipatory setting A standing pilot furnace has a bi-metal fan/ limit control. What are the factory settings - correct answer Fan on 125°F/Fan off 80°F/Limit cut out 200°F Type B vent pipe is constructed with an inner pipe and outer pipe. The inner pipe is made of - correct answer Aluminum HVAC Gas Heat certification exam Questions And Answers A GFCI circuit breaker detects - correct answer Current leaks to ground A homeowner complained that his furnace makes a loud bang upon ignition. The technician decides to check the gas pressure and finds 3.2 in. W.C. at the manifold. The technician should - correct answer Check supply gas pressure How much current does a typical flame sensor produce - correct answer 30 - 200 microamps A typical vent stack temperature on a NATURAL DRAFT furnace is - correct answer 450°F - 550°F A customer complains that a 2-year old gas furnace will not light. The technician determines that the furnace locks out while attempting to light. He reads 19 VAC at the gas valve and concludes - correct answer The electronic board is faulty The pilot assembly orifice of a spark ignition furnace is completely clogged. The technician should - correct answer Use an awl to clean it HVAC Gas Heat certification exam Questions And Answers Carbon monoxide is dangerous. What percentage of CO is acceptable in a sample of the flue gas - correct answer .04% A technician starts up a 5 year old natural gas furnace. The main burner lights and after 60 seconds the blower fan comes on, but the burner flames wavers in one corner. The technician suspects - correct answer A faulty heat exchanger A technician starts a spark type ignition furnace. The main burners light, but the spark ignited continues to spark. After 60 seconds, the blower fan comes on and the burner goes out. The technician suspects a faulty - correct answer Ignition board The proper instrument for calculating carbon dioxide in flue gas is a - correct answer Combustion analyzer If voltage is applied across two speed terminals on a fan motor, the motor will - correct answer Short out/burn out HVAC Gas Heat certification exam Questions And Answers The maximum external static pressure on a typical gas furnace blower system is - correct answer 0.2 - 0.6 in. W.C. Induce draft furnaces have a vent safety switch that should open at - correct answer 120°F Thermostat wire comes in two standard gauges - correct answer 18 and 16 AWG A technician solders a spade connectors to a wire. What type of solder should he use - correct answer Rosin core On a mid-efficiency induced draft furnace the anticipator is wired in series with the - correct answer Integrated circuit board To change the speed of a belt driven blower, the technician should - correct answer Adjust blower wheel pulley The formula (X= sensible heat BTU/h __________ HVAC Gas Heat certification exam Questions And Answers Failure to wire a replacement low voltage transformer in an electronic ignition furnace, based on its noted polarity, will - correct answer Short the PC board A spark ignited operates at _____ VAC - correct answer 10,000 The pressure inside an induced draft heat exchanger for a mid-efficiency furnace is approximately - correct answer +2" W.C. A furnace nameplate specifies a temperature rise of 40 to 70 degrees. Temperature measurements indicate a rise of 80 degrees. The most appropriate action is to - correct answer Increase fan speed A dedicated vent system - correct answer Is the only vent for an appliance Which of the following must be present for combustion to occur - correct answer Air, fuel and Ignition (Heat) HVAC Gas Heat certification exam Questions And Answers Which of the following statements is true of nitrogen - correct answer Nitrogen can combine with oxygen to form NOx Flashback indicates - correct answer The gas is flowing slower than the speed at which burn is occurring An inclined manometer measures - correct answer Pressures above 2" W.C. Fan speed should be set by - correct answer The temperature rise called for on the data plate Gas flow volume to natural gas furnace can be checked - correct answer Using the gas meter installed at the site If the exact amount of air is supplied and perfect combustion occurs, in a natural gas furnace, a specific percentage of CO2 content will be present in the flue gases. What percentage will be present - correct answer 2% to 5.5% HVAC Gas Heat certification exam Questions And Answers When a Category IV LP unit is properly installed and operating normally with 50% excess air, the CO2 content of the exhaust gases is - correct answer 10% to 14% While evaluation a gas valve that failed to open, the technician determined that; the gas valve knob was in the proper position thermostat was calling for heat the valve is an electric ignition type continuity of the main gas valve coil was good and proper voltage was present at the main gas valve coil terminal. What action should be taken next - correct answer The problem is the limit switch Building pressure diagnostic testing compares - correct answer Pressure in the whole building to the outside air.