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48 Cards in this Set
- Front
- Back
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What percentage of the air is impure |
1% Fly ash, pollen, and lint |
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Name three sources of indoor contaminants? |
a. Tobacco smoke b. engine exhaust c. industrial plants |
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10. List the four methods that mechanical filters use to filter air. |
a. Impingement b. Interception c. Straining d. Diffusion |
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2uM to inches? |
Nope This wont be a question |
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Does a higher MERV value indicate a greater or lesser efficient filter? |
Higher efficiency |
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12. List two devices that can be used to measure pressure drop of a filter. |
a. Magnehelic b. Manometer |
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List three types (categories) of filters. |
a. Mechanical b. Electronic c. Chemical(gas phase) |
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List the three sections (components) of an electronic air cleaner.
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a. Pre-filter b. Ionizing Section c. Collecting Section |
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What is the most common material used in adsorption filtration?
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activated carbon
Adddsorption |
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What is the most common chemical used in chemisorption filtration? |
Potassium Permanganate |
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What is UV-C good for? |
Mold growth |
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TQ: most commonly used for Mold and Viruses? |
Hepa |
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Most common problem causing Inaccurate zone control Constant air system? |
Same volute and temperature is supplied to all areas |
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What causes drafts and noise? |
Excessive flow High velocity Air leaks |
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What is a good building pressure? |
0.05 inWC • Prevent frozen pipes • Not blow the doors open • Not make the doors hard to open • Prevent gas appliance back drafting • Prevent mold from forming • Prevent drafting |
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What exactly is Stack effect? |
Stack effect occurs when the outside air temperature is significantly different than the inside air temperature. • Most common in hot or cold climates • Also called "chimney effèct" |
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What causes stack effect? |
Stack effect happens because warmer air is less dense and tends to rise Cooler air being more dense, tends to sink |
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How does stack effect… effect a office building in the winter? |
You heat the building, hot air rises, pressure outside is denser so it sucks in the cold air through the lower buildings. |
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What increases stack effect? |
Elevator shafts, height of building, difference in air temperature |
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TW: How does stack effect… effect a building in the summer? |
Cold air is produced to cooling the building and is pumped into the top floors bit it all sinks to the lower floors. This creates a negative in the upper floors and hot air is sucked into the higher floors. |
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TQ: what turns on a MUA in a parkade? |
CO detector |
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TQ: what turns on a MUA in a parkade? |
CO detector |
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TQ: What turns on an evaporative cooler? |
Outdoor ambient or thermostat in space
(Definitely temperature) |
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MUA with fireeye and you have a loose belt. What is the alarm? |
Flame failure because the high pressure and low pressure are in series with the flame sensor. Loss of flame will trip the alarm and need to be reset. |
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Tacky filters are what type of filters? |
Impingement |
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HRV use what type of heat exchangers? |
Cross flow They require a defrost 20-25F (-5C) |
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In order for enthalpy (energy) you will need water transfer so do some heat recovery ventilation with a membrane to allow for enthalpy transfer? |
Yes |
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Where are heat wheels located? |
Between the exhaust air and inlet air |
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How do you clean a heat wheel? |
Vaccuum only |
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Why does a heat wheel have a desiccant coating? |
To pull moisture out of the air and allow it to be held on the wheel. |
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What are you testing for alignment? |
Angular and parallel alignment |
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How do you find the shim height for a coupler? |
Performing a parallel alignment on a compressor involves adding the difference in measurement on the top and bottom of the coupling, dividing that measurement in half and raising or lowering the motor that distance by adding or removing shims. |
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How does a Lock out Relay function? |
normal operation CC is energized though automatic reset HPC+ LPL. - If safetes trip then LoR coil is energized and LOR-1 N/C Contacts open, Current flows through LoR relay coil which creates a large Voltage Drop, remaining voltage is insufficient to energize CC. - Unit can be reset by cycling Thermostat after automatic reset safeties have reset. - Purpose of impedance relay is convenience reset |
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How does a Lock out Relay function? |
normal operation CC is energized though automatic reset HPC+ LPL. - If safetes trip then LoR coil is energized and LOR-1 N/C Contacts open, Current flows through LoR relay coil which creates a large Voltage Drop, remaining voltage is insufficient to energize CC. - Unit can be reset by cycling Thermostat after automatic reset safeties have reset. - Purpose of impedance relay is convenience reset |
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What prevents infiltration into a building? |
Positive static pressure |
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What is the heat pump balance point? |
The point where the capacity of the home is exactly matched with the capacity of the heat pump at a given ambient temperature. Below this point you will need aux heat. |
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What is the benefit of face and bypass?
What will the setting be for a face and bypass system when the zone is satisfied? |
You can control temperature supplied without controlling the flowthrough the coil. When the zone is satisfied the damper is closed to the face and open to the bypass. Face and bypass require hot gas bypass to prevent evaporator freeze up when airflow through coil is low. |
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Why do you need hot gas bypass with an AC coil in face and bypass damper system? |
It allows the the evaporator to maintain suction pressure when bypassing the coil. |
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Dry air is more dense Cold air is more dense
The volume moved by the fan remains constant (because the fan is the same fan and there are inlet guide vanes)
So in the winter, you open up the outdoor air dampers what will happen to your amp draw? |
It will increase.
More free cooling = more amps Open outdoor air dampers on a hot humid day your amps will decrease. |
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How do you determine if static pressure increases or decreases With the use of an economizer? |
If the economizer opens is bringing in hotter wetter air the static pressure will decrease If the economizer opens and is bringing in colder drier air the static pressure will increase. |
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An air handler on a commercial building is generating complaints of noise (in the duct system and at the diffusers). What simple fix would you try to correct the situation and what effect would it have on the following |
Lower the fan speed and supply air temp
Fan supply amps (decrease) Supply air temp (decrease) |
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Vane axial fan is the most efficient fan? |
True |
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Can sleepers be made of combustible materials? |
No |
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Can sleepers be made of combustible materials? |
No |
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If your liquid line is piped through a warmer room it must be insulated? |
True |
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What is the minimum operating differential for a reversing valve? |
-Maximum allowable temperature difference across points of a reversing valve is 5 degrees Fahrenheit Reversing valve must be installed horizontally with discharge pilot tube facing up. Revering valves require 75-100 psi pressure difference to operate property -*f valve is stuck raise head pressure and switch between heating and cooling to free up valve. Fixed orfice system is charged to 10 degrees evaporator superheat -TXV system is charged to 10 degrees sub cooling |
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Most likely cause of water accumulation in duct work with steam humidifier? |
Most likely cause of water accumulating in the ductwork of a system with a steam humidifier would be a cracked steam distributor. |
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Fans move a constant volume So if Cold and dry air are more dense is entering through the economizer…. What happens to the amps? What happens to the static pressure? What will happen to capacity? |
Amps go up Static pressure goes up Capacity goes up because the air can do more work |
