HVAC
Math The latent heat of fusion for water is 144 BTU s Per Lb. The latent heat of vaporization for water is 970 Btu s per Lb.
Math F. to C. Conversion = (f-32)*(5/9) C. to F. Conversion = C * 9/5 + 32
Math Fan Formulas Flow to speed = (Q1/Q2=N1/N2) Pressure to Speed2 = (SP1/SP2=(N1/N2)2 Power to Speed3 = (KW1/KW2 = (N1/N2)3 Q= flow SP= Static Pressure KW= Power N = Speed
Math How many BTU s must be added to 1000 lbs of water to raise it s temperature 20 degrees.
Math Air Volume = Velocity (Feet per minute)*csa CSA= Cross sectional Area = 36 x 36 36in = 3f 600f.min.* (3f*3f)= 600f.min.*9f.f. = 5400
Math Water Boils at: 100 deg. C 212 Deg F.
Math Specific Heat is the amount per unit mass required to raise a mass one unit quantity.
Math One ton of cooling equals: 200 Btu s per min. 12,000 Btu s per Hr. 288000 Btu s per day
Math To raise the temperature of 20 lbs. of water 44 degrees.
Math The amount of BTU s to raise 5lbs. Of 22 Deg.F. ice to 50 Deg.F. Water
Physics How do you lower humidity
Physics Describe the refrigeration cycle and components
Physics Define infiltration
Physics Describe Latent Heat
Physics Describe Charles Law
Physics Describe Conduction
Physics Latent heat of fusion
Physics Describe Thermal Conductivity
Physics Define BTU s
Physics Describe coefficient of conductivity
Physics Enthalpy = heat content: (thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure
Physics Super Heat: To heat a liquid above its boiling point; To heat a vapor above its saturation point
Physics Matter exist in three states: Liquid, Solid, And Gas
Physics Define Convection
Physics Water has a specific heat of 1; higher than just about any other substance.
Physics Latent heat of vaporization of steam 970 Btu s
Physics Define heat of compression
Physics Describe the parallel between applied pressure and boiling point.
Physics Describe the laws of thermodynamics. First second
Physics Define work W=F*D W = Work F = Force D = Distance
Physics Under normal conditions the human body is only 11 percent efficient as a heat engine. This means that 89 percent of the metabolic heat...
Physics Define metabolic rate.
Physics Define the refrigeration process: Removing heat from a known source to an unobjectionable place.
Physics Describe Kinetic energy
Physics Solids usually have a definite shape and a definite volume. A given quantity of gas will fit into a container of any size and shape but is compressible A liquid has a given quantity and size but not shape
Physics A combustion reaction is when all substances in a compound are combined with oxygen, which then produces carbon dioxide and water
Physics viscosity is the quantity that describes a fluid's resistance to flow.
Physics The heat of condensation: Heat to change a substance from gas to liquid.
physics Define fluid
Physics Define conductivity
Physics Define the laws of conservation and heat flow.
Physics Define the law of perfect gases Boyles Charles Daltons
Fans. Describe Axial fan properties
Fans Define velocity
Fans The axial fans shaf runs parallel with the air and is usually use in low differential situations.
Fans Know the fan laws
Fans Define static duct pressure
Fans Define CFM
Fans Define the expression of duct pressure.
Fans Define Cubic feet per minute.
Fans Define forward curved fans
Fans Define the fan laws
Fans Review the fan laws
Fans Identify the different fan wheels
Fan Define static pressure
Psychometrics Describe the properties in the psychometrics chart.
Psychometric Define Wet Bulb Depression: The difference between the wet-bulb and the drybulb reading when readings are taken in the air.
Psychometric Describe how to calculate total building heat load.
Psychometrics Describe how humidistat's work.
Psychometrics Define Relative Humidity
Psychometrics Define Psychometrics.
Psychometrics Explain the psychometric Chart A chart that shows the relationship of temperature, humidity and pressure in the air.
Psychometric Define Dew-Point
Psychometrics On a psychometric chart the dry bulb temperature run lef to right from 20 to 105 deg.f.
Psychometrics Define effective temperature: The combination of temperature and humidity that provides the same comfort
HVAC What is comfort: Temp Humidity Filtration Volume ventilation
HVAC When air is heated Relative humidity goes down, wet-bulb temp raises, but dew-point stays the same.
Psychometrics Cold air leaving the evaporator is at 100% relative humidity.
Humidity Describe the places a person may want to raise the R.H. of an area.
Mechanical Describe the different types of compressors
Describe how a compressor works.
A helical compressor is a
Mechanical Pumps move water or other liquids Fans move air or other gaseous substances Compressors move air or other gaseous substances
Compressors The wider the compression ratio the less efficient the compressor. Compression ratio is absolute discharge pressure divided by the low side pressure.
Compressors Positive displacement compressors move a specific volume of refrigerant per RPM.
Compressors Heat of compression and mechanical heat are added to heat transfer.
Compressors The refrigerant absorbs the heat of compression.
Compressors Describe how a centrifugal compressor works.
Compressors Describe open compressors
Compressors Describe the different types of compressors maintenance requirements.
Compressors Compressors are refrigerant pumps
Compressors Where does the heat go.
Compressors Describe a rotary compressor
Compressors Describe chiller capacities
The refrigerant cycle
Compressors Define compression ratio
Compressors Describe the differences between positive and dynamic displacement.
Compressors What is a reciprocal compressor
Compressors Describe different types of compressors.
Compressor Describe an open compressor
Compressors Which is the most common type of compressor used in different applications.
Compressors Why do we need a crank shaf seal?
Compressors Describe amperage demand as compression ratio raises amperage raises.
Compressor
Condensers describe the three phases the refrigerant goes through.
Condenser Complete heat rejection theory.
Condensers What is the purpose of the condenser.
Condensers Use inhibited acid for cleaning
Condensers All refrigeration heat exchangers use reverse flow to maximum efficiency.
Condensers
Condensers
Condensers Condensers reject heat
Receivers
Condensers
Heat Exchangers Why is counter flow better than parallel flow.
Heat Exchange Describe where the heat goes and comes from.
Metering devices EPR
Metering Device Describe the metering devices used by chillers.
Metering Devices TXV maintain superheat
Evaporator Describe the phases of the evaporation process.
Metering Devices
Metering Devices Control flow of refrigerant into the evaporator.
Evaporator Changes liquid to vapor
Metering Devices The TXV sensing Bulb is filled with refrigerant.
Metering Devices TXV range from 6 Deg.f to 12 Deg. F of superheat pending on application.
Metering Devices Low-side floats control the amount of liquid refrigerant in the evaporator.
Metering Devices Explain Superheat.
Metering Devices Explain what an external equalizer does for the TXV.
Metering Devices Explain High-side float.
Metering Devices Define Metering Device.
Metering Devices
Metering Devices Ammonia systems rarely use hand operated valves, because they require manual regulations.
Metering Devices
Evaporators Absorb heat
Evaporators Evaporators absorb heat from the area or product being cooled.
Evaporator
Evaporators Shell and tube evap also store refrigerant.
Evaporators Cleanliness, surface area, metering device, latent heat, heat exchanger effect evaporator capacity.
Evaporators Hot Gas, natural, and electrical defrost are the most common defrost methods.
Evaporators Plate and Fin and tube are direct expansion evaporators.
Refrigerants R11, R12, R22, R123, and 134a are all refrigerants used in chillers.
Refrigerants Ammonia is considered harmful compared to most other refrigerants.
Refrigerants Old chillers used R-11.
Refrigerants Ammonia is the refrigerant of choice for large refrigerant systems.
Refrigerants Refrigerants should be stable, change state without damage, have a low boiling point, have a minimal GWP and ODP.
Refrigerant R22 has the highest condenser pressure.
Refrigerants Heat content is one of the thermodynamic properties of refrigerant.
Refrigerant Should be stable.
Refrigerants R-12
Accessories
Accessories Economizers increase efficiency.
Accessories
Accessories Piping loops allow for expansion and contraction of the piping.
Accessories Double Suction Line Drier.
Electrical DC capacitors are clearly marked.
Electrical The potential relay is wired parallel to the start winding.
Electrical Start options
Electrical 10% is the allowable voltage drop for refrigerant equipment.
Electrical RX1
Electrical Reverse motor directions.
Swamp Coolers / Evaporative Condensers
Swamp Cooler Wet-bulb temperature determines cooler efficiency.
Troubleshooting Moisture plugs driers.
Troubleshooting Power element lost its charge.
Troubleshooting Dirty filters allow the evap to freeze up.
Troubleshooting Low charge will freeze the evap coil.
Troubleshooting Too cold a condenser causes surging.
Troubleshooting The suction line must be small enough to keep the velocity high enough to return the oil.
Troubleshooting Dirty tubes cause poor heat transfer.
Troubleshooting Adding refrigerant to an undercharged system will cause the head and suction pressure to rise.
???? What were the five components of comfort.
Troubleshooting Low-side floats control refrigerant flow by keeping the evaporator full of liquid.
Troubleshooting Low head pressure causes a centrifugal compressor to surge.
Troubleshooting Nitrogen with a touch of R-22 is used to leak check.
Troubleshooting Sulfur causes corrosive oil.
??????? VFD
Troubleshooting Tstat measure temperature Pstat measure pressure Humidity stat measure moisture
Troubleshooting Oil separator remove oil from the discharge line and return it back to the compressor.
Troubleshooting Non-condensable are indicated by: High head pressure Hotter condenser temperatures Higher liquid line temperatures
Troubleshooting Water cooled condenser water could possible freeze with the sudden release of refrigerant.
Troubleshooting Discuss the different controls and the function of each control.
Troubleshooting No load no Head
??????? Copper, Steel and Iron are used to pipe ammonia systems.
Troubleshooting You should insulate the liquid line when the ambient temperature may be greater then the temperature of the liquid line.
Describe the oil pump process
Troubleshooting Too small a refrigerant line may cause: A reduction in compressor capacity Low head pressure Low amperage Excessive refrigerant pressure drop Lubrication problems