G2 Gas Technician Module 19 Revised Questions Rated A

G2 Gas Technician Module 19 Revised Questions Rated A If the venting on a high efficiency furnace runs through unheated spaces, what must be done? Insulate piping to prevent Condensation and freezing What is condensate drain piping used for? Dispose Liquid waste Once the furnace is installed, what are the gas technician's responsibilities to the user? To instruct the the user in the safe and correct operation of all appliances and equipment - clause 4.3.2 Which furnace type is the most popular? High boy Up Flow What type of furnace is used in areas of limited head room? Horizontal Forced Air What is the AFUE rating of a typical medium efficiency furnace? 78% - 82% Which category of furnace is standard atmospheric appliance? Category 1 Is a fan necessary to move the flue gases through a gravity vent? Why? No, hot air rises. Are high-efficiency furnaces power vented? Yes Which Vent is the most heat resistant? Type A On a forced draft burner, where is the fan located? Upstream from the combustion chamber. What is the disadvantage of oversizing a furnace? Inefficiency How is the delivered air volume adjusted if a belt-drive fan motor is being used? Adjusting the pulleys of the motor Must all defective heat exchangers be replaced immediately? Yes A high efficiency furnace incorporates how many heat exchangers? Two On a furnace with no filter rack, what should be done? Rack should be built on return duct connection What is a plenum? Duct work system connected directly to the furnace What should be done if a customer shows signs of Co poisoning? Evacuate, Shut off appliance, Call TSSA Once a fan motor has been cleaned what are the next two steps? Check electrical wire for tighteness and clean the blower components How is temperature rise determined? Placing thermometer in the return and supply plenums while the furnace is running What tool should be used to clean the outside of the heat exchanger? Soft Brush How many heat exchangers do Natural Draft Furnace have? One How is Delta Temperature measured? and what should it match? Supply Air minus Return Air, It must not be less or more than Manufacturers Rating Plate In a high efficiency furnace, which heat exchanger does the Supply air pass through first? The Secondary What proves that your Induce blower is functional? The pressure switch How is Hot Surface Igniter diagnosed? Connect leads to both wires, check for voltage and Resistance How is a belt motor in a furnace maintained? Must be Oiled and Alignment Where is the Automatic Damper located? Down stream of the draft hood What purpose does a Automatic damper serve? How does it work? Reduce heat loss up the chimney and it opens when burners fire and closes during the off cycle What is Static Pressure in a furnace?, how is it measured?, and what standard must it meet? The pressure in the furnace at 90 degrees. It's measured with a manometer It must meet Manufacturers Rating plate standard What are the possible causes of abnormal Static Pressure results? Dirty Air Filters andBlocked AC Evaporator Coil A Tee is required to be installed off the PVC 636 pipe, what is the component that should be attached? A Neutralizer with a hose leading to the drain trap In the event no sewer drain is present how is condensation water mitigated? A Condensation Pump Where must a furnace air filter be located and which direction? Arrow must face the negative pressure side of the Fan What does a pressure drop of 0.40'' w.c across the evaporator indicate? Dirty/Blocked AC Evaporator coil What is used to clean outside and inside a heat exchanger? Soft paint brush is used outside and wire brush is used for Corrosion build up When connecting the rectangle duct, which cleat is used on the longest area? and which is used on the shortest? S cleat on the longest and D cleat on the shortest What causes the fan to shut off under normal operating conditions? The fan control cools down enough to open the circuit to the fan When is a fan relay (Y pack) used? Combined heating and cooling operation What voltage usually operates the control module? 120V Which two documents must be adhered to if you replace a fan control? Manufacturers Specifications and the Electrical Code Does the replacement fan control have to be the same as the one being replaced? Yes On which types of furnaces would you find an auxiliary limit control? Down Flow an Horizontal Furnaces Do all rollout switches have to be manually reset? Yes What will cause the burner to shut down if there is a blockage in the vent? Vent outlet Pressure Switch How is a pressure switch tested to see if it is defective? With a manometer If the return air temperature is 70F and the temperature rise is 75F what is the supply temperature? 145F Before you start a Newly Installed Furnace what must be done? What step is after that? Measure Gas Pressure once done Measure Delta Temperature If you read 24V on the gas meter and the Valve doesn't open what could be wrong? The Valve is faulty and must be replaced The Main circuit board on a furnace is 120V, to connect a Accessory what must be done? A step down Transformer 24V must be use to match the accessory. Blowers with a belt normally have 1 speed, how is the speed adjusted? Remove set screws and rotate the pulley clockwise to tighten or counter clockwise to loosen Furnace air return runs at 68F, the blower sends air to heat exchanger and the temperature increases to 160F. What is our Delta Temperature? 92F temp rise What is the high limit switch safety temperature? 200F What must the return plenum on a furnace be able to do? Withstand negative air pressure What must the supply plenum on a furnace be able to do? Handle the maximum operating pressure of the furnace Balancing damper are used to? Slows the air flow in the duct and controls the air flow to each room Duct work system must be properly sized, what must a gas technician be aware of? Air quantities required and the number and type of supply outlets What must a Gas technician do before sizing or replacing a furnace? A Heat loss calculation What is the benefit of the secondary heat exchanger being heated first? It helps with heat transfer to condense flue gasses. How is a Heat Anticipatory selected? Based on Amperage Draw What are the 4 types of warm air furnaces? 1. Upflow (high boy) 2. Down Flow or Counter Flow 3. Horizontal 4. Low Boy Where is the supply and return on an Upflow Furnace? Supply is on the top and return air is near bottom Where is the supply and return on a Down Flow Furnace? Supply air is through the bottom and return air is through the top Where do you usually install a horizontal furnace? Positioned on its side usually in a crawl space or suspended from floor joists in basement. Where is the return air and supply air on a low boy furnace? Both are on the top How tall are low boys and where would you install them? Approximately 4 feet high and primarily installed in basements with low head room. What is the formula for Calculating CFM? BTUH (output)/ (1.1 x Temp difference) Where do you put your gauges when measuring temp rise? Out of sight of the heat exchanger in the supply duct and in the return air duct. Radiant heat can give higher readings What type of pilot does a natural draft furnace have? Standing How many heat exchangers does a conventional furnace have? Single heat exchanger What kind of efficiency does a natural draft furnace have? Max 70% What are the flue gas temperatures on a natural draft furnace? Over 350 F What kind of pilot does a mid efficient furnace have? Intermittent pilot What is the difference in a mid efficient furnaces heat exchanger compared to a natural draft one? Mid efficient is more restrictive What is the max efficiency of a Mid efficient furnace? 80 % What temperature are mid efficient furnaces flue gases? 250 F - 350 F How is a natural draft furnace vented? Naturally through a draft hood How is a mid efficient furnace vented? Assisted by fan through heat ex-changer and naturally through the venting How is a High efficient furnace vented? Under positive pressure What kind of ignition source is in a High efficient furnace? HSI/Spark How many heat exchangers does a high efficient furnace have? 2 heat exchangers a primary and secondary What does a high efficient furnace do that natural draft and mid efficient dont? It condenses What efficiency does a high efficient furnace operate at? 90%+ What flue gas temperatures does a High efficient furnace have? 80 F - 120 F What are the different types of gas valves? Single stage, 2 stage and modulating What is the big differences between the different types of gas valves? You get more comfort for the home owner. The least comfortable being the single stage and the most being the modulating gas valve. If a gas valve is working properly but a humming sound is heard the probable cause is? Low secondary voltage If a category 3 appliance is equipped with a electrically operated automatic vent damper when would it operate? When the damper is proven to be fully open before ignition of the main burner. On a category 1 appliance the high limit is always wired in series with what? Gas valve The top of a plenum should have what minimum clearance to combustibles? 1 " or 25 mm If the combustion air supply on a high efficient furnace is blocked what component would disable it? Pressure switch On a furnace with an integrated control board what controls the blower motor? Timer Relay Where do the condensate lines for a category 4 furnace run to? An open drain What methods would you use to determine if a heat exchanger is cracked? Smoke, visual inspection and flue gas analysis What is the average CFM per ton of an air conditioner 400 cfm per ton What is the average CFM per ton of a heat pump? 450 CFM What do you call the two heat exchangers in a high efficient furnace? Primary and secondary How far does a vent terminate from a mechanical air supply? 6 ft or greater Explain two stage furnace? Has a low fire and high fire. Improves comfort What controls the operation of a two stage furnace? Two stage thermostat