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### 55 Cards in this Set

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 What would happen if the fan on an electric unit heater burned out? The heater would remain energized until the fusible link melts OR the interlock switch would de-energize the electric heater. If a duct-mounted electric heater is to be installed and it is discovered that the heater is too long to fit inside the duct, what can the technician do to properly complete the installation? Return the heater to the supply house and obtain the correct size heater. The resistance wire used in electric heating elements is usually nickel chromium Radiant heat is trasferred by infrared rays Electric baseboard heaters are classified as natural draft convectors Quartz and glass panel electric units are classified as radiant heaters An electric heating unit in a duct system is classified as forced draft convector How do you measure Btu/h out of a 10 Kw furnace rated on 240V? 10,000 x 3.413 = 34,130 The limit switch is used on the electric element assembly to open the circuit to the element if the furnace overheats T or F: Generally speaking, electric heat is very efficient but costs more when compared to oil and gas. True T or F: For maximum element life, the element must have sufficient air over all parts of the element to prevent any part of the element from glowing red. True T or F: Electric heating units provide amost instant heat. Therefore, anticipators are not needed in electric heat thermostats. False T or F: If the number two contact on a package sequencer fails to close, the number three contact can still close False T or F: One potential safety hazard that all technicians should be aware of when working on an electric furnace is that there are many exposed electrical connections. True In order to prevent a duct-mounted electric heater from being energized when the fan is not on, an ________ should be used interlock A set of contacts actuated by a magnetic coil is called a ________ relay the amount of heat energy in 1 watt of electrical energy is ________ 3.413 If the fan were to fail and the limit switch stuck closed, the element would be cut off by the ________ Safety device In order to provide time delay between stages of electric heat, the controls that are used are called ________ sequencer How do you calculate CFM in an electric furnace? Watts x 3.413 / (1.08 * ΔT) How do you calculate CFM in a gas furnace? Btu output / (1.08 x ΔT) A gas valve system that has the gas valve and igition control all in one unit is called a smart valve When a pilot flame or a main burner flame is sensed (or proved) through the flame it is called flame rectification The manifold pressure of a natural gas furnace at low fire would be 1.7" WC When two furnaces are setup side by side to act as one furnace with multi stages of heat this installtion is called Twinning The orifice is a precisely sized hole in the spud The manifold pressure of a natural gas furnace at high fire would be 3.5" WC The typical manifold pressure of a propane furnace would be 11" WC What will shut off a gas valve if the furnace overheats? Aux limit switch The specific gravity of natural gas is 0.60 The proper color of a gas flame is blue with slight orange tips T or F: A gas flame will carry electrical energy True T or F: A gas furnace designed for use with natural gas can be used with liquified petroleum (LP) with no system modifications. False T or F: When a pilot flame or main burner flame is sensed by the IFC, the current it sees is measured in Milliamps. False, Microamps T or F: A thermocouple when it is heated generates around 20-30 microvolts False If the combustion gases are pushed through the heat exchanger the furnace is said to have a ________ draft. forced draft A ________ is located between the gas valve and the burners orifice Spark ignition is important for rooftop or package units located outdoors because of ________ problems. draft problems The dangerous byproduct of poor combustion of gas is ________ CO or Carbon-monoxide Three products of complete combustion of natural and LP gas are ________, ________, and ________. Water vapor, heat, and CO2 If the combustion gases are pulled through the heat changer, the furnace is said to have a ________draft Induced draft Why is "inches of water column" used to measure gas pressure instead of psig? The pressure is too small to accurately measure in psig. When the burners ignite, the burner flame is normal until the blower starts. At this time, continuous roll out occurs. What is the problem? A leak in the heat exchanger + not getting complete combustion 7 intermittent Pilot steps 1. Call for heat2. Gas to pilot opens3. Pilot is lit + proven4. Gas valve opens.5. Burner comes on.6. Burner proves7. Blower comes on 8 HSI steps 1. Call for heat2. Combustion blower comes on3. Prove combustion blower4. 16 second HSI5. Gas valve opens6. Burner gets lit7. Burner gets proved8. Blower comes on 7 Spark-Ignition steps 1. Call for heat2. Combustion blower comes on3. Prove combustion blower4. Spark/gas valve on5. Burner gets lit6. Burner gets proved7. Blower comes on 6 Standing pilot steps 1. Call for heat2. Gas valve opens.3. Pilot lights burner4. Burner comes on.5. Burner proves6. Blower comes on When a gas furnace ignites and is under "full-fire," why does the fan not come on immediately? The furnace needs to heat up What is the purpose of a gas regulator? To control the amount of gas coming in and out. Primarily used in crawl spaces Horizontal furnace Blower located above heat exchanger downflow furnace Blower located below heat exchanger Upflow furnace Return and supply ducts are both on top low boy What is a forced draft furnace? Push/blow with a positive pressureMounted on the inlet of the heat exchanger What is an induced draft furnace? Pull/suck air with a slight negative pressureMounted on the outlet of the heat exchanger