Gain a better understanding of the basic concept of air conditioning & air distribution

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 / Roof Top Unit (RTU) • VAV – Variable Air Volume • PIU – Powered Induction Unit • CRAC & CRAH – Computer Room Air Conditioners • and 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

5. What does the Evaporator do? • The purpose of the evaporator is to absorb heat from the air or water that is being conditioned. • The refrigerant begins to absorb the heat from the air or water and boils into a vapor. • The refrigerant is colder than the air or water, the heat migrates to the refrigerant and is removed from the air. • What now remains, is colder air.

6. What does a Compressor do? • The purpose of the compressor is to pump refrigerant vapor through the system and create a pressure differential. • High pressure, hot vapor, is pumped out of the compressor and into the condensing coil. • Compressors come in two different types- Hermetic and Semi-Hermetic. Hermetic are a welded tin can and are not serviceable and semi-hermetic are serviceable.

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

8. What does the Condenser do? • The condensers changes high pressure, high temperature vapor refrigerant, produced by the compressor, into a high pressure liquid. • This is performed by removing the heat from the high temperature refrigerant allowing it to condense. • The condenser will cool the refrigerant further to ensure the refrigerant remains a liquid as it reaches the metering devise. • Condensers are available in (2) types: water or air cooled.

9. Types of Condenser • Air cooled condensers are located outdoors incorporated with condenser fans to move outdoor air across the coils. • Water cooled units are located inside the CRAC or Air Handling unit. • Condenser water will need to be supplied to the condenser to remove the heat from the refrigerant. • The heat collected by the water will need to be rejected by other means to the outdoors.

10. Types of Condensers Typical Critical Systems Remote Condensers Fan Motor &Blade 1 – Fan Blade 2 – Protective Cover (Rain Shield) 23 – Fan Motor 24 – Sheave 25 - Shaft

11. What does the metering device do? • The metering device throttles the liquid reducing the pressure from a high pressure liquid to a low pressure saturated liquid. • It is located at the entering side of the evaporator. • Metering devices are available in several different types; Cap tube, Restrictor, Thermal Expansion Valve (TXV) and Electronic Expansion Valve (EXV). • TXV and EXV have the capability to control the flow of refrigerant into and throughout the evaporator.

12. Common HVAC Equipment • RTU’s • Air Handlers • VAV & PIU’s • CRAC & CRAH Units • Cooling Towers • Chillers

13. Typical Rooftop Packaged Unit 1. Compressor 2. Condenser coil 3. Condensate drain pan 4. Inducer fan 5. Control board 6. Heat exchanger 7. Filters 8. Evaporator coil 9. Belt driven blower motor 10. Condenser fan motor & blade 10 7 Draft Inducer Motor assembly

14. Typical Split System(Air Handler) • The split system absorbs heat and removes humidity along with supplying air flow to connecting duct work. • It houses a variety of components: filters, blower and coil. • The refrigerant or chilled water circulating through the coil absorbs heat as warm air travels across it. • Humidity collects on the cold surface of the coil, then drains down the coil and collects in a drain pan. It is disposed through the condensate drain.

15. VAV & PIU • VAV box is a Variable Air Volume damper assembly that supplies cold air to a zoned area • A VAV can be outfitted with a reheat devise. • PIU Box is a Power Induction Unit which includes a VAV damper, Blower type fan and a heat source. • These boxes are used to zone large areas or spaces that have a conditioned air supply by a large air handling unit. • Each box will have its own thermostat to control the box to satisfy the needs of the zone or space. • The PIU and VAV boxes are usually electronic and controlled by a Building Automation System. • Older style buildings or equipment may be controlled by pneumatics.

16. VAV – Variable Air Volume Box Shaft indicator and Damper Actuator Maybe Pneumatic or Electronic Inlet sized to fit all standard round ducts Velocity sensor tube Offers feedback to the damper controller Controller allows for maximum-minimum design settings, pressure independent control Maybe Pneumatic or Electronic

17. PIU – Powered Induction Box Heat options include Internal electric, hot water or steam heat to allow for staging 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 Velocity sensor tube Offers feedback to the damper controller Shaft indicator and Damper Actuator Maybe Pneumatic or Electronic Inlet sized to fit all standard round ducts Controller allows for maximum-minimum design settings, pressure independent control

18. CRAC and CRAH for the Data Center • A computer room air conditioning (CRAC or CRAH) unit is a device that monitors, maintains temperature, air distribution throughout the data floor and maintains humidity. • The CRAC unit is a Computer Room Air Conditioner and may be a perimeter or in-row unit configuration. • The CRAH unit is a Computer Room Air Handler and would be found in the ceiling or adjacent room. • In order to make the data center more energy efficient and better operation of the CRAC units, it is now recommended to operate the data center at higher temperatures. This will not damage the servers. *ASHRAE TC 9.9

19. Common Systems in Data CentersTraditional Perimeter Cooling / Raised Floor Design Cooling towers reject heat from the Condenser Water into the atmosphere Warm Return Air Hot and cold isle configuration CRAC Unit Cold Supply Air from the raised floor area

20. CRAC & CRAH CRAC / CRAH Air Handlers Typical Residential / Indoor Air Handler Wall Mount

21. Components of a CRAC Unit Contactors and Relays Circuit Board Disconnect Switch Line Driers Evaporator or Chilled Water Coil Compressors Blower Pulley, Shaft and Sheave Blower Motor

22. Cooling Towers

23. Cooling Tower • Remember water cooled condensers? • The cooling tower rejects heat from the condenser water loop that was collected from indoor cooling equipment. • Water enters the top of the cooling tower and is broken into smaller water droplets. • The water droplets fall through mist eliminators to the bottom basin of the cooling tower. • Ambient air is allowed to flow freely around the water droplets or drawn through by the tower fan for added heat rejection. • The cooled condenser water collects bottom basin and circulated back to the condenser loop to collect more heat from the indoor equipment.

24. Cooling Tower Types

25. Chillers • Chiller uses the basic principal refrigeration process to remove heat from water in the chilled water loop. The normal operating temperatures of a supply chilled water loop is 45 deg F. • Chilled water is used for comfort and process cooling. They can be used to lower the temperatures of many types of equipment, from machinery to main frame and server racks. • Chillers are available in different configurations and sizes that range from smaller 2 ton to the thousands of tons. • The chillers are offered with condensers in water or air cooler models. • Recent technology offers an oil free compressor and energy efficient option.

26. Chillers Air Cooled Screw Chiller Water Cooled Centrifugal Chiller Water Cooled Screw Chiller

27. Economizers • Economizer uses outside air = FREE COOLING • Whenever economizers are operating mechanical cooling is not required. • It makes use of the colder outside air to cool the indoor space. Both outdoor temperature and outdoor humidity can play a key role in when an economizer would operate. • Lowers the total cost of ownership. • Reduced CapEx by increased service life of the mechanical equipment. Reduces run hours. Equipment life can be doubled in some cases.

28. Economizers Energy saving: 15%-50%