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Introduction to HVAC Systems Presented by AirTight University

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1 Introduction to HVAC Systems Presented by AirTight University

2 HVAC User’s Guide Objectives
Gain a better understanding of the basic concept of air conditioning & air distribution Review different types of units Split-systems Chilled Water Systems Packaged Units VAV – Variable Air Volume PIU – Powered Induction Unit CRAC & CRAH – Computer Room Air Conditioners & Air Handlers Review the common components of each unit Review basic HVAC terms

3 Basic Components Air Conditioners and all refrigeration systems have Four main components: Compressor Condenser Metering Device Evaporator

4 Basics of Refrigeration Cycle
Metering Device Low pressure, liquid (gaseous mist) refrigerant from expansion valve to evaporator coil High pressure, liquid refrigerant from condenser coil to expansion valve Condenser Evaporator High temperature, high pressure, gaseous refrigerant from compressor to condenser coil Low pressure gas taking heat from evaporator to compressor Compressor

5 Common Systems in Data Centers Legacy Design (Raised Floor)
Condensers – Water or Air-Cooled Warm Return Air Air Handler Cold Supply Air

6 Typical Rooftop Packaged Unit
Condenser Fan Motor & Blade assembly 10 1. Compressor 2. Evaporator Coil 3. Condensate Pan 4. Gas & Electrical connectors to roof 5. Control Board 6. Heat Exchanger 7. Base rail 8. Condenser fan motor 9. Belt drive blowers 10. Condenser Fan Motor & Blade Draft Inducer Motor assembly

7 VAV – Variable Air Volume Box
Precision machined zinc plated solid steel shaft Self lubricating nylon bearings for long life and reliable low friction operation Insulation is 1”, two pound density and complies with UL 181 and NFPA 90A requirements Damper design features a full diameter contact seal that maintains less than 1% air leakage at pressures up to 4” water gauge Seismic tabs are standard for easy installation S & Drive connection for rapid field installation Inlet sized to fit all standard round ducts Shaft indicator shows damper position Direct drive, rack & pinion actuator maintains precise control by eliminating hysteresis and blade vibration Multipoint averaging velocity sensor amplifies airflow signal for greater accuracy Gauge taps for direct flow measurement and field balancing Controller allows for maximum-minimum design settings, pressure independent control

8 PIU – Powered Induction Box
Internal electric, hot water or steam heat to allow for staging of heat in conjunction with the fan running and the cooling damper closing off. Internal electric fan to provide recirculated air as the first stage of heat, generally used for perimeter zones Multipoint averaging velocity sensor amplifies airflow signal for greater accuracy Insulation is 1”, two pound density and complies with UL 181 and NFPA 90A requirements Direct drive, rack & pinion actuator maintains precise control by eliminating hysteresis and blade vibration Damper design features a full diameter contact seal that maintains less than 1% air leakage at pressures up to 4” water gauge Controller allows for maximum-minimum design settings, pressure independent control Inlet sized to fit all standard round ducts

9 CRAC - Computer Room Air Conditioner & CRAH – Computer Room Air Handler
A computer room air conditioning (CRAC or CRAH) unit is a device that monitors and maintains the temperature, air distribution and humidity in a computer room or data center. As the I.T. industry grows, so does the need for removing the heat from the mission critical facilities. Mainframes and racks of servers can get as hot as a seven-foot tower of powered toaster ovens, so climate control is important part of the data center's infrastructure. One configuration that has been successful is the process of cooling air and having it dispensed through an elevated floor. The air rises through the perforated sections, forming cold aisles. The cold air flows through the racks where it picks up heat before exiting from the rear of the racks. The warm exit air forms hot aisles behind the racks and the hot air returns to the unit intake, which are positioned above the floor. The inverse concept can be utilized with an overhead delivery as well.

10 Common Parts Evaporator Coil Expansion Valve Liquid Line Drier

11 Types of Condensers Typical Critical Systems Remote Condensers
Mini Split Typical condenser– Residential of office

12 Condensing Unit Components
Fan Motor & Blade Condensing Coil 1 – Fan Blade 2 – Protective Cover (Rain Shield) 23 – Fan Motor 24 – Sheave 25 - Shaft Filter Line Dryer compressor

13 What does this “stuff” do?
The Condensing Unit – The condensing unit is located outdoors and is responsible for removing the heat that was captured indoors. A compressor, located within the condensing unit, circulates the refrigerant throughout the system. The Remote Condenser – The heat rejection component that dissipates heat when the compressor is with the CRAC unit. The Condenser Fan – As refrigerant travels through the condenser coil it begins to cool down. A fan blowing across this condenser coil speeds up this process and is critical in facilitating the transfer of heat to the outside air. Filter Dryer – Removes impurities and moisture that could be in the refrigerant system.

14 Types of Compressors Reciprocating Compressor Scroll Compressor
Centrifugal compressor Screw Compressor Rotary Compressor Oil-less Compressor

15 What does a Compressor do?
The purpose of the compressor is to pump refrigerant vapor/gas through the system and create a pressure differential. A metering device creates the restriction needed to separate the high side pressure from the low side pressure. High pressure, hot gas is pumped out of the compressor and is cooled into a high pressure liquid by the time it leaves the condensing coil. This liquid is fed through a metering device into the evaporator coil and turns into a low pressure gas by the time it leaves. It returns to the compressor as a low pressure gas ready to repeat the process.

16 Types of Air Handlers CRAC / CRAH Air Handlers Wall Mount
Typical Residential / Indoor Air Handler

17 Components of an Air Handler
Contactors and Relay’s Circuit Board Disconnect Switch Line Driers Evaporator Coil Compressors Blower Pulley, Shaft and Sheave Blower Motor

18 What does the Air handler Do?
The Air handler absorbs heat and removes humidity. It houses the filters, blower and evaporator. The refrigerant circulating through the evaporator coil absorbs heat as warm air travels across it. Humidity also collects on the cold surface of the evaporator and drains down the coil and collects in a drain pan and is disposed of down the condensate drain. The air handler draws filtered air over the evaporator coil. The cooler drier air gets pushed through the duct work by the blower and is diffused throughout the designated space to maintain the desired temperature and humidity levels within that designated space.

19 So how do these systems work together?

20 Cooling Towers

21 Cooling Tower Types

22 Chillers Water chillers are everywhere - they are used to air condition large industrial, commercial and institutional facilities and are used to lower the temperatures of all kinds of equipment, from machinery to computer parts and server racks. Basically, the principal is, the chiller removes heat from (cools) a liquid, usually water, then circulates the cooled liquid through a chilled water circuit to provide cooling to each of the connected air handling units. CRAH units utilize this technology in many applications.

23 The entire system working together

24 Economizers Applied in the shelter air conditioning unit
Outdoor type packaged A/C Installed in Shelter Free cooling box Applied in the shelter air conditioning unit Energy saving: 15%-50%

25 The Reasons for Economizers are Many
To lower the total cost of ownership – In many locations there is a substantial opportunity for OpEx savings over the life of the equipment operation. This is largely due to the 365x7x24 operation of the facilities and cooling needs. When ever economizers are operating (making use of outside air temperatures) mechanical cooling is not required. Makes use of the colder outside air to cool the indoor space. Bot outdoor temperature and outdoor humidity can play a key role in when an economizer would operate. Reduced CapEx by increased service life of the mechanical equipment. When economizers are in full economizer mode, compressors are not. This reduces the amount of run hours of the equipment. Equipment life can be doubled in some cases. Reduced OpEx associated with the refrigerant circuit (compressor, etc.) – same as item 2 above.

26 Economizers = savings!

27 Definition of Common HVAC Technical Terms

28 HVAC terms Acid Condition in System – Condition in which refrigerant or oil in system is mixed with fluids that are acid in nature. Actuator – That portion of a regulating valve which converts mechanical fluid, thermal energy, or electrical energy into mechanical motion to open or close the valve seats. Air Diffuser – Air distribution outlet or grille designed to direct airflow into desired patterns. Air Handler – Fan-blower, heat transfer coil, filter and housing parts of a system. Air Cooled Condenser – Heat of compression is transferred from condensing coils to surrounding air. This may be done either by convention or by a fan or blower. Back Pressure – Pressure in low side of refrigerating systems; also called suction pressure or low-side pressure. Bearing – Low friction device for supporting and aligning a moving part. Belt – a rubber-like, continuous loop placed between two or more pulleys to transfer rotary motion. Boiler – Closed container in which a liquid may be heated and vaporized. Brazing – Method of joining metals with nonferrous filler (w/out iron) using heat between 800F (427C). Btu-British Thermal Unit – Quantity of heat required to raise temperature of one pound of water one degree Fahrenheit.

29 HVAC terms Capacitor – Type of electrical storage device used in starting and/or running circuits on many electric motors. Capacity – Refrigeration rating system. Usually measured in Btu per hour or watts (metric). Charge – Amount of refrigerant placed in a refrigerating unit. Circuit – Tubing, piping or electrical wire installation which permits flow to and from the energy source. Circuit Breaker – Safety device that automatically open an electrical circuit if overloaded.   Compressor – Pump of a refrigerating mechanism which draws a low pressure on cooling side of refrigerant cycle and squeezes or compresses the gas into the high-pressure or condensing side of the cycle.  Condensate – A fluid formed when a gas is cooled to its liquid state. Condensate Pump – Device to remove water condensate that collects beneath an evaporator. Condensation – Liquid or droplets which from when a gas or vapor is cooled below its dew point  Condenser, Air-Cooled – Heat exchanger which transfers heat to surrounding air.  Condenser, Water – Cooled – Heat exchanger designed to transfer heat from hot gaseous refrigerant to water. Condenser Coil – Made of copper tubing, this is where the hot Freon is compressed to squeeze the heat out of it.

30 HVAC terms Condenser Fan – Forced air device used to move air through air-cooled condenser.  Condenser Fan Motor – Enables fan to blow air across the surface of the Condenser coil carrying away the heat. Condensing Pressure – Pressure inside a conde3nser at which refrigerant vapor gives up its latent heat of vaporization and becomes a liquid. This varies with the temperature. Condensing Temperature – Temperature inside a condenser at which refrigerant vapor gives up its latent heat of vaporization and becomes a liquid. This varies with pressure.  Condensing Unit – Part of a refrigerating mechanism which pumps vaporized refrigerant from the evaporator, compresses it, liquefies it in the condenser, and returns it to the refrigerant control.  Control, Low-Pressure – Cycling device connected to low-pressure side of system. Cooling Tower – Device which cools by water evaporation in air. Water is cooled to wet bulb temperature of air.***** Cut-In – The temperature value or the pressure value at which the control circuit closes Cut-Out – Temperature value or pressure value at which the control circuit opens. Cycle – Series of events or operations which have tendency to repeat in the same order. 

31 HVAC terms Damper – Device for controlling airflow.
Defrost Cycle – The process of removing ice or frost buildup from the outdoor coil during the heating season. Detector, Leak – Device used to detect and locate refrigerant leaks. Drier- Substance or device used to remove moisture from a refrigeration system. Drip Pan – Pan-shaped panel or trough used to collect condensate from evaporator. Duct – Tube or channel through which air is conveyed or moved.  Enthalpy – Total amount of heat in one pound of a substance calculated from accepted temperature base. Temp of 32F (0C) is accepted base for water vapor calculation. Evaporation – Term applied to the changing of a liquid to a gas. Heat is absorbed in this process  Evaporator – Part of a refrigerating mechanism in which the refrigerant vaporizes and absorbs heat. Evaporator Coil – Typically made of copper, carries cold gaseous Freon that absorbs heat from air traveling over the surface of the coil. Evaporator Fan – Fan which increases airflow over the heat exchange surface of evaporators.  Expansion Valve – Device in refrigerating system which reduces the pressure from the high side to the low side and is operated by pressure. Fan – Radial or axial flow device used for moving or producing flow of gases. Filter – Device from removing small foreign particles from fluid or air. Flexible Duct – A duct that can be routed around obstacles by bending it gradually.

32 HVAC terms Float Valve – Type of valve which is operated by sphere or pan which floats on liquid surface and controls level of liquid.  Freeze-Up – 1) Formation of ice in the refrigerant control device which may stop the flow of refrigerant into the evaporator. 2) Frost formation on an evaporator which may stop the airflow through the evaporator. Freon – Trade name for a family of synthetic chemical refrigerants manufactured by the DuPont Company. Fuse – Electrical safety device consisting of strip of fusible metal in circuit which melts when circuit is overloaded. Gas Valve – Device in a pipeline for starting, stopping or regulating flow of gas. Gasket – Resilient (spongy) or flexible material used between mating surfaces of refrigerating unit parts. Grille – Ornamental or louvered opening placed in a room at the end of an air passageway. Head Pressure – Pressure which exists in condensing side of refrigerating system. Head Pressure Control – Pressure operated control which opens electrical circuit if high-side pressure becomes too high. Head Pressure Safety Cut-Out Motor protection device wired in series with motor; will shut off the motor when excessive head pressures occur.

33 HVAC terms Heat Exchanger – Device used to transfer heat from a warm or hot surface to a cold or cooler surface. (Evaporators and condensers are heat exchangers.  Heat Load – amount of heat, measured in Btu or watts, which is removed during a period of 24 hours. Heat Pump – Compression cycle system used to supply heat to a temperature-controlled space. Same system can also remove heat from the same space  High Pressure Cut-Out – Electrical control switch operated by the high-side pressure which automatically opens electrical circuit if too high pressure is reached. Humidity – Moisture dampness of air.  Junction Box – Box or container housing group of electrical terminals. Liquid Line – Tube which carries liquid refrigerant from the condenser or liquid receiver to the refrigerant control mechanism.  Low Pressure Safety Cut-Out – Motor protection device that senses low-side pressure.  Moisture Indicator – Instrument used to measure moisture content of a refrigerant. Motor – Rotating machine that transforms fluid or electric energy into a mechanical motion.

34 HVAC terms Motor Burnout – Condition in which the insulation of an electric motor has deteriorated. Motor Control – Device to start and/or stop a motor at certain temperature or pressure conditions. Motor Starter – high-capacity electric switchers usually operated by electromagnets. Oil, Refrigeration – Specially prepared oil used in refrigerator mechanism which circulates, to some extent, with refrigerant. Open Circuit – Interrupted electrical circuit which stops flow of electricity. Operating Pressure – Actual pressure at which the system works under normal conditions. This pressure may be positive or negative. (vacuum).  Overload – Load greater than that for which system or mechanism was intended  Overload Protector – Device, either temperature, pressure, or current operated, which will stop operation of unit if dangerous conditions arise. Package Units – Complete refrigerating system including compressor, condenser, and evaporator located in the refrigerated space. Pressure Switch – Switch operated by a rise or drop in pressure. PSI – Symbol or initials used to indicate pressure measured in pounds per square inch.

35 HVAC terms Pulley – Flat wheel with a “V” groove. When attached to a drive and drive members, the pulley provides a means for driving the compressor or blower wheels.  (AKA Sheave) Purging – Releasing compressed gas to atmosphere through some part or parts for the purpose of removing contaminants from that part of parts. Refrigerant – Substance used in refrigerating mechanism. It absorbs heat in evaporator by change of state from a liquid to a gas, and releases its heat in a condenser as the substance returns from the gaseous.  Refrigerant Control – Device which measures flow of refrigerant between two areas of a refrigerating system. It also maintains pressure difference between high-pressure and low-pressure side of the mechanical refrigerating system while unit is running.  Refrigerant Dye – Coloring agent that can be added to refrigerant to help locate leaks in a system.  Refrigerant Reclaim – To reprocess refrigerant to new product specifications. This will require chemical analysis, and usually refers to the processes available at a reprocessing or manufacturing facility.  Refrigerant Recovery – To remove refrigerant and place in a cylinder without necessarily testing it.  Refrigerant Recycling – To remove refrigerant and place in a cylinder without necessarily testing it.  Refrigerant Recycling – To clean refrigerant fro reuse by reducing moisture, acidity and matter. Usually applies to procedures at job site or local service shop.

36 HVAC terms Register – Combination grille and damper assembly covering an air opening or the end of an air duct.  Relay – An electromagnetic mechanism moved by a small electrical current in a control circuit. It operates a valve or switch in an operating circuit. Relief Valve – Safety device on a sealed system. It opens to release fluids before dangerous pressure is reached. Remote System – Refrigerating system in which condensing unit is away from space to be cooled. Retrofit – Term used in describing reworking an older installation to bring it up to date with modern equipment or to meet new code requirements.  Reversing Valve – Device used to reverse direction of the refrigerant flow, depending upon whether heating or cooling is desired. Safety Control – Device to stop refrigerating unit if unsafe pressure, temperatures, and/or dangerous conditions are reached.  Safety Motor Control – Electrical device used to open circuit to motor if temperature, pressure and/or current flow exceed safe conditions. Safety Valve – Self-operated, quick opening valve used for fast relief of excessive pressures. Schrader Valve – Spring-loaded device which permits fluid flow in one direction when a center pin is depressed and in other direction when a pressure difference exists.

37 HVAC terms Sensor – Material or device which goes through physical change or electronic characteristic change as surrounding conditions change. Service Valve – Manually operated valve mounted on refrigerating systems used for service operation. Short Circuit – Electrical condition where part of circuit touches another part of circuit and causes all or part of current take wrong path. Short Cycling – Refrigerating system that starts and stops more frequently than it should. Shroud – Housing over condenser, evaporator or fan. Sight Glass – Glass tube or glass window in refrigerating mechanism. It shows amount of refrigerant or oil in system and indicates presence of gas bubbles in liquid line. Slugging – Condition in which mass of liquid enters compressor causing hammering. Soldering – Joining two metals by adhesion of a metal with a melting temperature of less than 800F. (427C)  Solenoid Valve – Electromagnet with a moving core. It serves as a valve or operates a valve. Split System – Refrigeration or air conditioning installation, which places condensing unit outside or away from evaporator. Also applicable to heat pump installations.  Squirrel Cage – Fan which has blades parallel to fan axis and moves air at right angles or perpendicular to fan axis.

38 HVAC terms Suction Line – Tube or pipe used to carry refrigerant gas from evaporator to compressor. Suction Pressure Control Valve – Two-way, manually operated valve located at the inlet to compressor. It controls suction gas flow and is used to service unit  Suction Side – Low-pressure side of the system extending from the refrigerant control through the evaporator to the inlet valve of the compressor. Superheat – 1) Temperature of vapor above its boiling temperature as a liquid at that pressure. 2) The difference between the temperature at the evaporator outlet and the lower temperature of the refrigerant evaporating in the evaporator. Thermocouple - Device which generates electricity, using principle that if two unlike metals are welded together and junction is heated, a voltage will develop across the open ends. Thermostat – Device which senses ambient temperature conditions and, in turn, acts to control a circuit. Thermostatic Expansion Valve (TXV) – Control valve operated by temperature and pressure within evaporator. It controls flow of refrigerant. Control bulb is attached to outlet of evaporator. Transformer – Electromagnetic device which transfers electrical energy from primary circuit into variations of voltage in secondary circuit. 

39 HVAC terms Vacuum Pump – Special high efficiency device used for creating high vacuums for testing or drying purposes.  Valve – Device used for controlling fluid flow.  Vapor Lock – Condition where liquid is trapped in line because of bend or improper installation. Such vapor prevents liquid flow. VAV- Variable air volume.  V-Belt – Type of belt commonly used in refrigeration work. Has a contact surface with a pulley which in the shape of a V. Velocity – Quickness or rapidity of motion, swiftness, speed. Ventilation – Forced airflow, by design, between one area to another.

40 Questions?

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