| Making Cool Things Colder | Boilers | Compressors | HVAC | Tricks of the trade |
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Metering devices
Cap tubes, TXVs and EEVs are examples of what component in a refrigeration system?
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Locate the highest heat source and estimate height from boiler. Every 2.3 Ft of water equal 1 PSI.
Example: 30Ft high heat source. 30FT/2.3=13PSI static
How do you calculate the appropriate static pressure for a boiler system?
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Liquid floodback.
What does excess ice buildup on a compressor body indicate?
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100Ω
Hot surface igniters are recommended to be replaces at or above what resistance (in ohms)?
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Hot water.
When thawing a frozen refrigeration coil, what is the fastest way to melt the ice-buildup?
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Outlet of the evaporator.
Where is the temperature sensing bulb for a Thermal Expansion Valve located in a refrigeration system?
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Inspect the volute design.
How do you determine the direction a circulation pump is moving fluid?
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Oil pressure and compressor crankcase pressure
What values do you need to accurately calculate a semi-hermetic compressors “Net Oil Pressure”?
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Red,Blue,Yellow,Green, White
24V, Common,Cool, Fan, Heat
On a typical 5 wire thermostat, what are the 5 wire colors and their designated function?
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Verify power is off.
What is the most important step when working on any high-voltage piece of HVAC/R equipment?
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Liquid flood back.
What is excess liquid refrigerant in the suction line returning to the compressor called?
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Forced-draft and Induced-Draft.
Forced-Draft blowers focus the pressure and volume at the outlet of the fan to push air through a system, creating positive air pressure. Induced draft fans operate by focusing the pressure and volume at the inlet of the fan to pull air through a system.
What are two types of combustion blower draft configurations?
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Control cooling capacity
What is the purpose of an unloader valve on a semi-hermetic compressor?
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Heat exchanger, burners, induced draft-motor
Name 3 faulty parts that could contribute to high CO in combustion flue gas.
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Turn off gas.
When checking gas pressure on any heating equipment, it is critical to do this before connecting a manometer.
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To decrease liquid refrigeration temperature; increase energy efficiency and system capacity.
What is the purpose of a mechanical subcooler?
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7-8PH
What is a standard boiler fluid PH level?
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Scroll and screw compressors.
Which types of compressors are rotation specific and cannot operate if incorrectly phased?
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16F-22F, confirm with manufacturer specifications
What is a satisfactory temperature differential (DELTA T, ΔT) for an RTU?
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Gather all necessary information; Pressures, Voltages, etc.
Before requesting tech support from a fellow technician, it is important to do this first.
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Freezer 6F-8F
Cooler 8F-10F
On a commercial refrigeration system, how many degrees of superheat are we trying to achieve at the outlet of the evaporator?
List temp for both coolers and freezers. |
160F-180F
Typically, what temperature should a boiler system utilizing variable air volume with reheat be set at?
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Check resistance of motor windings; ohm out
On a 3 Phase compressor, what is the best way to verify motor winding integrity?
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Constant Air Volume. Designed to maintain a constant air supply to space.
What is a CAV rooftop unit?
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Check in with management or facility supervisor
What is the 1st thing you should you do when entering a commercial facility?
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