Term
| Face velocity of a return grille should be limited to |
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Definition
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Term
| If a packaged heat/cool unit is equipped with an economizer |
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Definition
| provide "free cooling" on certain days of the year |
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Term
| Face velocity of a supply register should be? |
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Definition
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Term
| When installing an economizer it is important to check |
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Definition
| that the vanes do not bind during operation |
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Term
| you just finished installing a 60,000 btuh output gas furnace and now you need to determine the volume of air that is flowing out of this furnace. you measure the supply temperature to be 105 F and the return temperature to be 68 F. What is the CFM at the bonnet |
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Definition
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Term
| The sensible heat equation can be used to determine air flow in which of the following systems |
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Definition
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Term
| a manufacturer recommends a temperature rise between 35F and 55F. You have a temperature rise of 60F. How should you resolve this? |
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Definition
| increase the blower speed |
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Term
| what could cause a higher than recommended temperature rise over a furnace |
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Definition
|
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Term
| once a gas piping system has been assembled it should be pressure tested with |
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Definition
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Term
| a piping system that is pressurized with natural gas should be leak tested with |
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Definition
| an electronic leak detector and/or soap bubbles |
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Term
| electronic leak detectors are calibrated in |
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Definition
|
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Term
| what type of soap solution should be used to check for gas leaks? |
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Definition
| one specifically designed for that purpose |
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Term
| which of the following is a diaphragm type differential pressure gage |
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Definition
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Term
| a differential pressure gage reads pressures that are |
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Definition
| differential or relative to atmosphere |
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Term
| a high supply side static pressure is an indication of |
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Definition
| a clogged evaporator coil |
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Term
| a high return side static pressure is an indication of |
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Definition
|
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Term
| why do you cross break ductwork |
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Definition
| to add strength and rigidity |
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Term
|
Definition
| the average CFM based on the average velocity multiplied by the square feet of duct |
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Term
| a direct drive blower wheel with damaged or missing vanes can cause |
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Definition
| loss of air flow, motor damage and noise |
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Term
| during a PM call on a gas furnace you find loose and corroded wires. What, if anything, should be done? |
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Definition
| retighten all loose wires and replacethe corroded portions of the wires |
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Term
| when preparing to perform an air balancing procedure |
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Definition
| all volume dampers should be open, the blower should be adjusted to the desired speed, and the air filter should be cleaned or replaced |
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Term
| which of the following should be included in an air balancing report |
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Definition
| supply, return, and total static pressure |
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Term
| in a trunk and branch duct system, trunk velocity should be kept between |
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Definition
|
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Term
| horizontal runs of flexible duct should be supported every |
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Definition
|
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Term
| minimum strap width for hanging flexible duct is |
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Definition
|
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Term
| maximum sag for horizontal runs of flexible duct is |
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Definition
|
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Term
| ductwork installed in unconditioned spaces should be |
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Definition
|
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Term
| ducts installed in damp crawl spaces should be |
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Definition
| wrapped with insulationand wrapped with a vapor barrier |
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Term
| human comfort can be defined in terms of |
|
Definition
| dry bulb temperature, relative humidity, and air velocity |
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Term
| The proper manifold pressure for natural gas is |
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Definition
| 3.2" to 3.8" of water column |
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Term
| the proper manifold pressure for LP gas is |
|
Definition
| 11" to 13" of water column |
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Term
| inlet pressure to a gas valve should never exceed |
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Definition
|
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Term
| in a combination gas valve |
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Definition
| the pilot valve is in series with the main valve |
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Term
| a two stage gas valve has? |
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Definition
| two pressure regulators and two main valves |
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Term
| manometers used to measure gas pressure are calibrated in |
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Definition
|
|
Term
| when reading a u-tube manometer |
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Definition
|
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Term
|
Definition
| 27.72" of water column and 2.3' hd. |
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Term
| the older mechanical thermostats and the newer electronic thermostats |
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Definition
| are made to be compatible |
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Term
| which of the following thermostat types can be programmed for a different time schedule each day of the week |
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Definition
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Term
| to choose the proper air cleaner for a given application you must know? |
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Definition
|
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Term
| which of the following would be used to delay the off time for a blower |
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Definition
|
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Term
| which of the following is a category I furnace? |
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Definition
|
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Term
| venting a two pipe condensing furnace through the roof requires a maximum separation of the two pipes of |
|
Definition
|
|
Term
| when horizontally venting a condensing gas furnace be sure to |
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Definition
| maintain a 12" separation between the inlet and the outlet of the two pipoes |
|
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Term
| when venting a category IV furnace what is the minimum separation from the vent pipe discharge to a forced air inlet into the building |
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Definition
|
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Term
| relative to combustion air a confined space is defined as |
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Definition
| an area with less than 50 ft^3 of volume for each 1000 btuh of input for all appliances in that area |
|
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Term
| what is the required volume of air to sustain combustion? |
|
Definition
| 50 ft^3 per 1000 btuh input |
|
|
Term
| combustion air can be supplied to a confined space by |
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Definition
| one opening within 12" of the floor and one opening within 12" of the ceiling |
|
|
Term
| in venting tables for category I furnaces the "Vent Height" can be defined as |
|
Definition
| the distance from the outlet of the draft diverter to the chimney cap |
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Term
| the primary heat exchanger is typically made of |
|
Definition
|
|
Term
| the secondary heat exchanger is typically made of |
|
Definition
|
|
Term
| a counterflow furnace installed in a closet must be mounted on |
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Definition
|
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Term
| what else is important with regard to a closet installation of a two pipe 90% furnace in a residence |
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Definition
|
|
Term
| an attic installation of a horizontal gas furnace requires |
|
Definition
| the use of a zero clearance furnace or a non-combustible mounting base |
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Term
| on a call for heat with an induced draft furnace, which of the following is the next event in the sequence of operation |
|
Definition
| draft inducer is energized |
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Term
| on a no heat call you find the following: R to W is made, The inducer is running, no main burner. What is most likely the cause of these symptoms? |
|
Definition
| A pressure switch stuck closed |
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Term
| on a call for heat the integrated circuit board will check for which of the following before energizing the draft inducer? |
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Definition
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|
Term
| what device proves that the inducer motor is running and that the venting system is not obstructed |
|
Definition
|
|
Term
| on a call for heat, after the pressure switch closes the next event is |
|
Definition
|
|
Term
| on a call for heat, after the HSI is energized the next event is |
|
Definition
| main burner circuit is energized |
|
|
Term
| on a call for heat, after the main burner is energized the next event is |
|
Definition
|
|
Term
| on a call for heat, after the flame is proven the next event is |
|
Definition
| blower motor is energized |
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Term
| the products of complete combustion include |
|
Definition
| co2, nitrogen, water vapor, and heat |
|
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Term
|
Definition
| is mixed with the gas in the venturi before ignition |
|
|
Term
|
Definition
| is supplied to the burner after ignition to sustain combustion |
|
|
Term
| too much primary air can cause |
|
Definition
| the flame to lift off the burner |
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|
Term
| which of the following produces a hard, noisy blue flame |
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Definition
|
|
Term
| ribbon burners must be properly aligned |
|
Definition
| to insure proper flame carry-over |
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|
Term
| modern residential gas burners are made from |
|
Definition
|
|
Term
| which ignition system is de-energized once the main burner flame is established |
|
Definition
|
|
Term
| the pilot flame must envelope how much of the thermocouple |
|
Definition
|
|
Term
|
Definition
|
|
Term
| the ACCA manual used to perform residential load calculations is |
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Definition
|
|
Term
| AFUE can be calculated by |
|
Definition
|
|
Term
| a large difference between the wet bulb and the dry bulb temperatures is an indication of |
|
Definition
|
|
Term
| which of the following is used to measure RH% |
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Definition
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