Electric Heat ESCO - HVAC Excellence Exam Questions and Answers, Exams of Electrical Engineering

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Electric Heat ESCO - HVAC Excellence Exam

Questions with Correct Answers.

Before working on an electric furnace the tech should - Correct answer Review diagram, remove jewelry, and follow safety procedures. ALL OF THE ABOVE. A GFCI circuit breaker - Correct answer detects current leaks to groound the conductor in an electric heat element is usually made of - Correct answer Nichrome An example of resistive load is - Correct answer crankcase heater an example of an inductive load is - Correct answer motor an electric furnace is marked 208/230 single phase 60Hz A tech reads 200 vac at the power supply and determines - Correct answer the voltage is too low voltage imbalance between any leg of 3 phase power supply may not exceed - Correct answer 2% the limit switch on an electric furnace is a - Correct answer Automatic reset switch the sequencer timers on electric heater will usually energize the 1st heating element after a time delay of - Correct answer 1 to 30 sec the amount of btus produced by 1 watt of electricity is - Correct answer 3.413 btus a tech reads 60 amps with a clamp on amp meter on a forced air furnace. the supply voltage is 230 volts AC, approx how many watts is the furnace using - Correct answer 13, a furnace is using 15,500 watts approx Kw - Correct answer 15.5 Kw

a sequencer timer use _____ to close the contact points to the heater element - Correct answer heated snap-discs or bi-metal strips an electric furnace heating thermostat must - Correct answer open on rise close on drop a standard thermostat heat anticipator is ____ and wired in ____ with the heating control - Correct answer adjustable/series some thermostat manufacturers require a jumper connection on the thermostat subbase of heating and cooling thermostat in order to - Correct answer use a single transformer most electric heat elements use the following safties to prevent overheating

• Correct answer snap disc and fusible link a tech reads 70 amps to the single phase heater. the supply voltage is 230 volts Ac. Approx how many btus is the furnace producing - Correct answer 54, the control that prevents duct heater from operating unless there is adequate supply air is - Correct answer fan interlock the COP for electric resistance heat is - Correct answer 1 to 1 what is the maximum kW element used on each contact of a residential heat sequencer - Correct answer 5 kW electric heaters are generally rated at ____ volts ac for kW output - Correct answer 240 the first stage of a sequencer usually has a set of contacts to - Correct answer start the blower fan motor an automatic reset safety on a heater element generally opens at ____F - Correct answer 130-190F most heating elements are mounted on which type of insulator - Correct answer mica or ceramic

a 10 kW electric heater operating at 240 v draws 42 amps, what will a 10 kW heater wired to 480 volts draw - Correct answer 21 amps the purpose of a sequencer is to - Correct answer avoid a sudden power load two major factors in determining the temp rise of an electric furnace are - Correct answer furnace KW and CFM a major cause of electrical heat element burn out - Correct answer low airflow a tech is checking the resistance on delta wired 3 phase 240 v 15 kW electic duct heater if one element is open he would read - Correct answer L1 to L2 22Ohm L1 to L3 22ohm L2 to L3 infinity the purpose of setting a heat anticipator properly is to - Correct answer control cycling time a 10 kW heater installed in a 2 ton central air conditioning heating furnace should have an air flow of _____ CFM - Correct answer 600 - 800 resistance to air flow (static pressure) in an electric heater is measured in - Correct answer inches water column to properly set a heat anticipator the tech should measure the amps between terminals __ and ___ on subbase - Correct answer R-W a tech is installing a 3 ton cooling system with a 15 kw electric furnace. the thermostat would require wiring a minimum of ____ conductors - Correct answer 4 a 1/3 single phase PSC electric blower motor would draw approx ___ at 240 v AC - Correct answer 2-4 amps on a delta wired heater a tech reads L1 to L2 11 ohm L1 to L3 22 ohms and L2 to L3 11 ohm - Correct answer element between L1 and L3 is shorted a 1200 CFM furnace operating with a 10kW heater at 240 v AC would have a temp rise of ______ *F - Correct answer 20 - 30

A tech is checking the output of a 5 kW supplemental heater used with a heat pump. The heating element is controlled by what stage of the thermostat - Correct answer Auxiliary heating To measure supply grill air speed, the tech should use an - Correct answer anemometer when installing a rooftop heating and cooling unit, to prevent condensate pan problems you should - Correct answer trap the drain line the contact points of a sequencer on a live heater may be checked by using this meter - Correct answer voltmeter when removing any high voltage component for safety the tech should - Correct answer lock out/tag out power panel the best method to install a flexible duct to a metal collar is to - Correct answer tie wrap and mastic the inner and outer liners most residential AC and electric heating system will have a fan system rated for a maxium total pressure loss of - Correct answer 0.40 - 0.50 WC (inches of water column) to adjust the airflow on a heater with a belt driven blower you should - Correct answer adjust the motor pulley the driven belt width used on fractional HP motor is - Correct answer A typical RPM of residential direct driven blower is - Correct answer 1000 - 1200 RPM turning vanes are added to sheet metal elbows to - Correct answer increase air velocity the maximum recommended return air velocity of a residential filter - Correct answer 400 fpm a rigid residential duct system should be desgined for a maxium trunk velocity of ____ FPM - Correct answer 700 - 1,

hot spots on the electric heater strip are most often caused by - Correct answer insufficient airflow over heater strip a tech is selecting replacement motor for a furnace. what type of bearings should be used for low noise level - Correct answer Sleeve a tech should use this type of oil to lube blower motor - Correct answer 20 viscosity non-detergent most fractional HP motors use this type motor mount in central electric furnaces - Correct answer resilient mounted a tech is measuring the voltage to a 3ph 240 VAC blower motor. the readings are L1 to L2 238 volt, L1 to L3 240 volt, L2 to L3 241 volts these reading indicate - Correct answer the voltages are within allowable tolerances a motor used in an electric furnace is rated at 230 VAC what is the minimum and maximum voltages allowed - Correct answer 207 to 253 a tech reads 5 FLA on data plate approx what should the LRA be - Correct answer 15 to 25 amps a tech checks a fan motor run capacitor to ground with an analog ohmeter what resistance scale should be used - Correct answer r X 10K a tech is checking the ressitance of a multi speed blower motor the reading are high to common 10 med to common 12 low to common 14 start to common infinity these reading indicate - Correct answer the motor has an open start winding the heating elements in a single phase 15 kW heater are usually wired in - Correct answer parallel

this type of switch is used to detect supply airflow - Correct answer pressure differential the contact points on a de-energized heater relay are checked by using this meter - Correct answer ohmeter a multi speed PSC motor has a start winding and - Correct answer a run capacitor a grounding strap must always be used with this motor mount - Correct answer resilient motor the best description of a fuse link safety is - Correct answer a one time device a megger meter is used to check motors for - Correct answer winding insulation quality a tech takes the temp rise of an electric furnace what is being measured - Correct answer sensible heat only a typical electronic air cleaner will trap ____ % of air particulates - Correct answer 95 - 100% which one of the following filters will create the highest static pressure drop

• Correct answer pleated fiberglass the recommended minimum relative humidity for good air quality in a home during the heating season is - Correct answer 40% one inch of fiberglass has an R value of approx - Correct answer 3 circuit protection of ___ amps is used for each 5 kW of heat - Correct answer 30 a good method to improve overall indoor air quality is - Correct answer increase ventilation a HEPA filter can remove dust particles down to _____ microns - Correct answer 1-

when converting a residence that uses a gas or oil heat system to electric resistance heating, you should - Correct answer overall insulation quality which of the following is not a type of electric resistance heating wire used in residential applications - Correct answer glass enclosed what type of safety is recommended for use with baseboard electric heat - Correct answer limit switch to determine the proper heat anticipator setting - Correct answer measure the total current in the 24v circuit that passes through the thermostat control bulb and heat anticipator duct heatesr are used generally for - Correct answer auxiliary heaters a tech 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 good description of how a sequencer operates the blower motor on an electric furnace is - Correct answer time on - time off a BTU is the amount of heat required to raise the temp of one pound of water - Correct answer one degree F an installed furnace should have a minimum of ____ inches for service access - Correct answer 30 what instrument would a tech use to calculate return airflow to a furnace - Correct answer velometer the auxiliary terminals on an electric sequencer is normally rated at - Correct answer 24v .5 amps you are installing 2 sections of a rectangular sheet metal duct to main supply line what connectors are used to secure sections of the trunk line - Correct answer S connectors and drive clips

metal ductwork tends to transmit noise and fan vibrations to conditioned spaces in residential installations. what types of connectors are specified to control this - Correct answer flex connectors fiberglass duct wrap is used to insulate round metal ducts. what is the apporx R - value for 1 inch of this insulation - Correct answer between r- & what size copper conductor would normally be used to connect the electrical circuit from the disconnect to a 10kW electric furnace - Correct answer 10 AWG on a dual transformer system which terminal on the thermostat sub base is used to power the heating system - Correct answer RH the national electrical code classification for thermostat wire is - Correct answer NEC class 2 if voltage is applied across 2 speed terminals of a fan motor the motor will - Correct answer short out a wall mounted thermostat should be installed approx ___ inches above the floor - Correct answer 48 to 60 commonly used thermostat wire comes in 2 standard gauges - Correct answer 18 and 20 AWG a tech solders a spade connector to a wire what type of solder should be used - Correct answer 95/ a furnace blower motor is rated at 230 v what would be in the allowable voltages variance - Correct answer +- 10% the first stage of the most electric heat sequencers in residential furnace turns on the_____ - Correct answer 1st stage elements or blower and the 1st stage elements the formula (x = sensible heat BTU/h / (1.08 X TD) - Correct answer CFM

A tech needs to run thermostat wire 90 ft. to keep voltage drop at a minimum the tech should use - Correct answer 16 AWG When measuring the temperature split for an electronic furnace, make sure the temperature probe is not what? - Correct answer affected by radiant heat Which type of heat will make items in a room warm to the touch? - Correct answer Radiant heating panels How many amps are used for each 5 kW of heat? - Correct answer 15 Amps Which of the following is used in heating doorways, inside, or outside work areas? - Correct answer Radiant spot heating