Term
| the energy efficiency ratio (EER) is the input in Btu/hr divided by the output in watts....True or False? |
|
Definition
| FALSE---EER is calculated by taking the OUTPUT in Btu/hr and dividing it by the INPUT in watts |
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|
Term
| What gauge thermostat wire is typically used on residential systems? |
|
Definition
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|
Term
| Normally, what is the maximum length Normally, what is the maximum length a line set can be run on many residential split system air conditioners |
|
Definition
|
|
Term
| What micron level should be achieved when evacuating a system? |
|
Definition
|
|
Term
| What is the required air flow across the evaporator of a split system air conditioner? |
|
Definition
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|
Term
| What is another heat source added to make up the difference between the heat pump capacity and the house load? |
|
Definition
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|
Term
| The difference between a COP and an HSPF is that COP is the ratio of heat out divided by heat in and is measured at one condition.HSPF is a measure of heat per watt and is measured ________________. |
|
Definition
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|
Term
| Which of the following is not a configuration for air source packaged units?--Over-under,Side-by-side,Wall mount,Curb mount, Up-and-over,Convertible. |
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Definition
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|
Term
| In a heat pump cycle,what keeps both metering devices from being in the refrigeration circuit at the same time? |
|
Definition
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|
Term
| What type of thermostatic expansion valve allows refrigerant flow in both directions?Some meter in both in directions,whereas others only meter in one direction and allow free flow in the other. |
|
Definition
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Term
| Review the following conditions:a)Floodback on the cooling cycle:An air restriton through the indoor coil will lead to a light load,low superheat,and liquid floodback. b)Floodback on the heating cycle:Excessive frost buildup on the outdoor coil as well as low airflow will lead to a low superheat and liquid floodback. c)Termination of the defrost cycle:Liquid floodback will always occur when the defrost cycle is terminated.In each situation, what is needed to protect the compressor in a heat pump system? |
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Definition
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|
Term
| A defrost cycle may be activated by ____________________________. |
|
Definition
1.low suction pressure.
2.low suction or liquid line temperature.
3.high static pressure drop across the outdoor coil.
4.the heat pump operating timer. |
|
|
Term
| What type of heat pump is most commonly used for residential application? |
|
Definition
|
|
Term
| How is heat transferred in a heat pump ground loop? |
|
Definition
|
|
Term
| The most efficient air-to-air heat pumps have an HSPF_______. |
|
Definition
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|
Term
| The Energy Star label is awarded to those air-to-air units withSEERs of 14 or greater and HSPFs_________ |
|
Definition
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|
Term
| Ina direct expansion system, the primary refrigerant evaporates and expands, absorbing both sensible and latent heat.In contrast, a secondary refrigerant does not evaporate and therefore only absorbs______________. |
|
Definition
|
|
Term
| Which of the following is not of the different configurations of air source packaged heat pumps? |
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Definition
|
|
Term
| What is the main consideration when sizing an air source heat pump? |
|
Definition
| Building heat loss & heat gain |
|
|
Term
| How does over sizing a heat pump affect its efficiency? |
|
Definition
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|
Term
Match the data plate ratings with their description.
A:Power wire to unit must be able to carry at least this many amps;to size the power wire
B:Largest fuse or breaker that may be used
C:Rating load amps of the compressor;gives the approximate operating compressor amp draw
D:Highest voltage unit can safely operate
E:Full load amps;gives the approximate operating fan amp draw
F:Lowest voltage unit can safely operate |
|
Definition
C-RLA,
E-FLA
F-MINIMUM VOLTAGE
D-MAXIMUM VOLTAGE
A-MINIMUM CIRCUIT AMPACITY
B-MAXIMUM OVER CURRENT PROTECTION |
|
|
Term
| Instruments used for measuring duct pressure include____________. |
|
Definition
| Inclined manometer,digital manometer, & magnehlic gayge |
|
|
Term
| What horsepower motor will be reqired to increase the airflow of a fan to 1,000 CFM if a 1/4 horsepower motor is required to move 800 CFM? |
|
Definition
|
|
Term
| What are the two broad types of fan designs? |
|
Definition
|
|
Term
| The two main types of fan drives are_________? |
|
Definition
| direct drive and belt drive |
|
|
Term
| What speed does a fan need to turn to increase its airflow from 800 CFM to 1,000 CFM if the original speed is 230 rpm? |
|
Definition
|
|
Term
| What is the most common fan used in residential air conditioning? |
|
Definition
| Forward curve centrifugal fans |
|
|
Term
| The method to measure airflow using temperature rise is __________. |
|
Definition
Measure the system temperature rise
1.look up the system Btuh output capacity
2.use the formula:
CFM=Btuh/ 1.08 x Temp Rise |
|
|
Term
| How is the CFM at a suppky register determined using a velometer? |
|
Definition
| The air velocity is measured and multiplied by the free area of the supply register |
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|
Term
| What can cause the total airflow leaving the supply registers to be much lower than the amount of air the blower is moving? |
|
Definition
| Leaks in the supply side ductwork |
|
|
Term
| How can TAB improve the health of the occupants? |
|
Definition
| TAB is seen as pat.of indoor air quality, which can have a benicicial effect on occupants |
|
|
Term
| What are the 3 enviromental conditions that have the most effect on comfort? |
|
Definition
1.temperature
2.humidity
3.and air movement |
|
|
Term
| How is the air volume affected by temperature? |
|
Definition
| Air volume increases as the air temperature increases |
|
|
Term
| What is the relationship between air volume and air weight (density)? |
|
Definition
| Increases.in temperature increase the volume & decrease the weight |
|
|
Term
| What is the temperature where water vapor can begin condensing out of the air? |
|
Definition
|
|
Term
| Rlative humidty is the actual weight of the water in each pound of dry air,measured in grains.Specific humidity compares the amount of water in the air to the amount of water the air can hold at a given temperature.....TRUE or FALSE? |
|
Definition
|
|
Term
Match the list of air properties that are plotted on a psychometric chart to the brief description of each.
A.Expresses the percentage of water vapor in the air compared to the amount of water vapor the air can hold.
B.The normal air temperature in degrees fahrenheit
C.The temperature of a thermometer with a wetbulb in degrees F.;the wet bulb temperature reading takes the moisture in the air to account
D.Measures the space in cubic feet occupied by each pound of air
E.Measures the weight of water vapor in the air in grains
F.Measures the total heat content of the air in Btu per pound of air
G.Measures the temperature where water will start to condense out of the air |
|
Definition
B-DRY BULB
F-ENTHALPY
E-SPECIFIC HUMIDITY
D-SPECIFIC VOLUME
A-RELATIVE HUMIDITY
C-WET BULB
G-DEW POINT |
|
|
Term
| What would the mixed air temperature be for a system with 20% outdoor air if the outdoor temperature is 10*F. and a return temperature is 75*F>? |
|
Definition
| 62°F mixed air temperature |
|
|
Term
| IF a PTAC unit had an output of 6600 Btu/hr & 660 watts input,what would be the SEER of the unit under standard conditions? |
|
Definition
|
|
Term
| What are the metering devices used on most PTAC units? |
|
Definition
| Most PTAC units use rotary compressors and capillary tube metering devices |
|
|
Term
| Wich types of compressors are commonly used for chillers? |
|
Definition
| Reciprocating,centrifugal and screw |
|
|
Term
| There are two general types of air handling units that are used for central plant systems: ones with remote air handling units, called fan coils units, and ones with.......... |
|
Definition
| Central station air handling units |
|
|
Term
| The components of an FCU include fans, water coils, filters,a fresh air supply, and.......... |
|
Definition
|
|
Term
| What are two basic types of fans used in most AHUs |
|
Definition
|
|
Term
| How should ultraviolet germicidal lamps be handled? |
|
Definition
| Always use gloves and wipe clean after handling |
|
|
Term
| What is the purpose of a filter status differential pressure switch? |
|
Definition
| This switch triggers an alarm when the filters become dirty |
|
|
Term
| What is the function of a low temperature thermostat on a packaged air handler? |
|
Definition
| It will be set to shut down the fan and set off an alarm if the air temperature drops below 35 degrees |
|
|
Term
| What is the purpose of a high pressure switch in a packaged air handler? |
|
Definition
| This switch will shut down the fan if the duct pressure exceeds the set point |
|
|
Term
| What will an air quality sensor typically measure? |
|
Definition
| CO2 levels in the conditioned space |
|
|
Term
| To determine if a ladder is correctly set up, one method is that for every _ feet that the ladder is extended, it should be one foot out from the wall it is leaning against |
|
Definition
|
|
Term
| Besides the manufacturer, the rooftop unit installer might consult for proper unit installation information in the local codes, the uniform mechanical code book, the international mechanical code book, and...... |
|
Definition
| The national fuel gas code |
|
|
Term
| What is one of the main reasons that rooftop units have to be level? |
|
Definition
| For the condense to drain properly |
|
|
Term
| Where can weight fof a rooftop unit be found? |
|
Definition
| Specific weights can bd found in the manufacturers installation instructions |
|
|
Term
| What code specifies the correct way fof electrical connections to be made? |
|
Definition
|
|
Term
| If PVC pipe is usdd for the construction oc the drain line, what must be done to prevent deterioration of the pipe, and what causes this deterioration? |
|
Definition
| The PVC drain line should be insulated to prevent deterioration from UV radiation |
|
|
Term
| What is the customers number one concern relative to the rooftop unit? |
|
Definition
| That the unit works properly |
|
|
Term
| If a direct expansion coil delivered from the factory has lost its nitrogen press charge, what should be done? |
|
Definition
| The coil has a leak and should be returned |
|
|
Term
| How should an external equalizing line for a TEV be connected to a horizontal run? |
|
Definition
| The external equalizing line should be connected to the top of the tube |
|
|
Term
| What type of water should be used in a chilled water system? |
|
Definition
| Distilled water with corrosion inhibitors |
|
|
Term
| How should hot water heating coils be piped? |
|
Definition
|
|
Term
| What function of an energy recovery unit? |
|
Definition
| Energy recovery units serve to pre cool and dehumidify the outdoor air during the cooling season and pre heat and humidify it duting the heating system |
|
|
Term
| What types of systems ptovide an excellent means of moduling control operation; provide a wide variety of control sequences with relatively simple equipment; are relatively free of operational l.p. roblems; no cost less than electrical controls if the codes require electrical conduit? |
|
Definition
|
|
Term
| What is the function of a purge recovery unit? |
|
Definition
| A purge recovery unit will purge thd air from the top of the condenser and recover the refrigerant on a continuous basis while the chiller is running |
|
|
Term
| What precaution should be taken for coolers that are located outside? |
|
Definition
| Thd cooler shell (evap) must be protected from freezing; electric heating elements are wrapped around the shell anx then covered with a thick layer of jnsulation |
|
|
Term
| Why are tge cooler shell and suction ljne insulated on a unit that is located indoors? |
|
Definition
|
|
Term
| How can tge centrifugal compressor speed be higher than the motor speed? |
|
Definition
| By using speed increasing gears |
|
|
Term
| What is the difference between a single stage and a two stage centrifugal compressor? |
|
Definition
| A single stage onlg has one impeller, and the two has two impellers |
|
|
Term
| What is the most efficient method of capacity control for a centrifugal compressor? |
|
Definition
|
|
Term
| What is the purpose of a chiller economizer? |
|
Definition
| To subcool the refrigerant before it enters tbe cooler |
|
|
Term
| What is the purpose of an oil return.system for a.chiller? |
|
Definition
| The oil return system requirements turns and re-introduces the system oil back into the compressor lubricating circuit. |
|
|
Term
| How should refrigerant be transferred.friends m a chiller? |
|
Definition
| Always begin the refrigerant transfer Friday m a chiller unit using liquid recovery methods. |
|
|
Term
| What could happen if you charge liquid refridgerant into a chiller that.is under a deep vacuum? |
|
Definition
| The refridgerant will immediately flash, the chiller will.freeze up, and the tubes will crack to cause extensive.damage to the chiller |
|
|
Term
| What is the term,defined as a science,for utilizing water or steam to transfer heat from the source where it id produced,to an area where it can be used,through a closed system of piping? |
|
Definition
|
|
Term
| What was the common choice.for hydronic piping in the past,and how is.that changing? |
|
Definition
| It was copper,but it is now changing to new materiald such as cross-linked polyethylene. |
|
|
Term
| Saftey measures that are used to allow for expansion in a hot water heating system include using both temperature and pressure limiting controls to maintain the water within safe conditions;using a pressure relief device supplied in the piping to relieve excess pressure should it occur;and using.a(n)________provided in the piping,partly filled with air,to permit normal expansion and contraction of the water. |
|
Definition
|
|
Term
| How does a.two-pipe system,reverse return,differ from two-pipe system,direct return? |
|
Definition
| The two-pipe reverse return system is similar to the direct return.system except that the piping is arranged so that the same length of pipe (supply + return) is used for each terminal unit. |
|
|
Term
| Hot water is controlled to a zone by the thermostat.that either activates the circulator pump for the zone or_____________. |
|
Definition
| Activates a zone control valve. |
|
|
Term
| A radiant floor heating zystem transfers.heat by conduction and convection........TRUE or FALSE? |
|
Definition
|
|
Term
| How dors an.open.piping.system differ from a closed.piping system? |
|
Definition
| An open system has some part.or the circuit open to the atmosphere,such as in a circulating how to water heatin system. |
|
|
Term
| Most water circulating pumps used in hydronic systems are the ________ type. |
|
Definition
|
|
Term
| Most hot water boilers heat up to what temperatures? |
|
Definition
| A hot water heater typically heats water to a final temperature of 180 to 200°F |
|
|
Term
| At what temperature do radiant floor heating systems typically operate? |
|
Definition
| Radiant floor heating systems are much lower than most other heating systems operating at 85-140°F. |
|
|
Term
| What is the typical return water temperature for a gas fired boiler? |
|
Definition
|
|
Term
| What is the working pressure for a low-pressure boiler? |
|
Definition
| Low-pressure boilers have a working.pressure of.u to 15-psi steam and/or up this 160-psi water pressure at a maximum of 250°F operating temperature. |
|
|
Term
| What is the heating input for a low-pressure residential boiler? |
|
Definition
| Residential heating boilers are gas and oil.fired.boilers.with inputs.less.than.300,000 Btu/hr. |
|
|
Term
| What is the.working pressure.for.medium- and high-pressure boilers? |
|
Definition
| Medimum- and high-pressure boilers operate above 15-psi steam and/or over 160-psi water pressure.at temperatures above 250°F. |
|
|
Term
| How many Btu's are required.to change a pound of water to a pound of steam at 212°F.? |
|
Definition
|
|
Term
| What types of expansion tanks are welded gas tight and have a flexible rubber membrane between the air space and the water space that moves during operation to allow for the changing volume of water? The air is precharged (usually 12 psig for residential units) into the expansion tank and,unlike the closed type,does not come in contact with the water in the.system. |
|
Definition
| Diaphragm expansion tanks |
|
|
Term
| What is the pressure relief valve typically set at on a residential or small commercial system? |
|
Definition
|
|
Term
| What device can be used to maintain boiler water temperatyre by controlling boiler firing? |
|
Definition
|
|
Term
| What are the two common mechanical draft cooling tower arrangements? |
|
Definition
| Induced draft or forced draft. |
|
|
Term
| How is the heat load for a cooling tower calculated? |
|
Definition
| It is equal to the pounds of water circulated multiplied by the cooling range. |
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