Introduction to HVAC Systems: Types & Working Guide

CONTENTS

• HVAC Introduction
• Split Systems
• VRF Systems
• Chilled Water Systems
• CRAC

HVAC System

Definition:

HVAC stands for heating, ventilation, and air-conditioning. The HVAC system is used to provide heating or cooling to space along with proper ventilation. The HVAC system provides thermal comfort, humidity control, proper ventilation, and clean/filtered air.

Most commonly used Systems

Split (DX) system: One evaporator and one condenser unit.

VRF system: Multiple evaporator units connected to one condenser unit.

Window AC: A single package unit encasing the evaporator and condenser. Located at or below the window.

PTAC unit: Similar window AC. Located below the window. Unlike windows, AC includes multiple options for heating.

Chilled water system: The system utilizes chilled water for cooling the air to the required temperature.

Split (DX) System

ADVANTAGES:

1. SIMPLE INSTALLATION
2. LOW CAPITAL COST
3. SERVICE/MAINTENANCE
4. COOLING/HEATING
5. RESIDENTIAL BUILDING

DISADVANTAGES:

1. BUILDING AESTHETICS
2. HIGH OPERATING COST
3. SERVICE/MAINTENANCE IS DIFFICULT FOR LARGE SCALE
4. MORE SPACE IS REQUIRED FOR LARGE SCALE
5. LIMITATION OF REFRIGERANT PIPING LENGTH

VRF System

DX vs. VRF System:

HVAC SYSTEMS

What is happening Inside AC?

• Indoor Unit (Evaporator)
• Hot Air is passed In – Cold Air is passed out
• Liquid Refrigerant In – Vapour refrigerant out
• Outdoor Unit (Condenser)
• Vapour Refrigerant In – Liquid Refrigerant out
• In contact with Surrounding cold air

Difference between VRF & Split AC

• Multiple indoors for the same outdoor
• Advantage w.r.t Space
• Advantage w.r.t Efficiency
• Advantage w.r.t Power Consumption

Difference between VRF & Chilled Water Systems

Up to 65 indoors for one outdoor. What if more? The refrigerant piping length limitation

Chilled water system

• Chilled water instead of Refrigerant as media
• No piping length limitation
• No indoor units connected limitation
• More COP, less initial & operating cost

Centralized Air conditioning

Water Side components

1. Chiller
2. Chilled water Pumps
3. Chilled water Piping
4. Air Separators
5. Expansion Tanks
6. Valves

Air Side components

1. Air handling Units / Fan Coils
2. Diffusers
3. Dampers
4. Fans

CRAC

1. Unit
2. Airflow Distribution
3. Dx Type
4. Chilled water Type

Relevance to other Disciplines

HVAC SYSTEMS	INPUTS	OUTPUTS
SPLIT & DX SYSTEMS	ARCHITECTURAL – ENVELOPE LOAD & OCCUPANCY ELECTRICAL – ELECTRICAL EQUIPMENT LOAD STRUCTURAL – BEAM LAYOUT	ELECTRICAL- VOLTAGE, CURRENT, PHASE STRUCTURAL – WEIGHT OF PACKAGED ROOF TOP UNITS PLUMBING – HEATING LOAD IF GAS HEATING
VRF	ARCHITECTURAL – ENVELOPE LOAD & OCCUPANCY ELECTRICAL – ELECTRICAL EQUIPMENT LOAD STRUCTURAL – BEAM LAYOUT	ELECTRICAL- VOLTAGE, CURRENT, PHASE STRUCTURAL – WEIGHT OF OUTDOOR UNITS
CHILLED WATER SYSTEMS- AIR SIDE	ARCHITECTURAL – ENVELOPE LOAD & OCCUPANCY ELECTRICAL – ELECTRICAL EQUIPMENT LOAD STRUCTURAL – BEAM LAYOUT	ELECTRICAL- VOLTAGE, CURRENT, PHASE STRUCTURAL – WEIGHT OF AIR HANDLING UNITS PLUMBING – HEATING LOAD IF GAS HEATING
CHILLED WATER SYSTEMS- WATER SIDE	CLIENT, PM – TYPE OF CHILLER, ARCHITECTURAL – ENVELOPE LOAD & OCCUPANCY ELECTRICAL – ELECTRICAL EQUIPMENT LOAD STRUCTURAL – BEAM LAYOUT	ELECTRICAL- VOLTAGE, CURRENT, PHASE STRUCTURAL – WEIGHT OF EQUIPMENTS OF CHILLER PLANT
AIR-TERMINALS/DIFFUSER /GRILLES	ARCHITECTURAL – RCP/LIGHTING LOCATION SPRINKLER – SPRINKLER HEAD LOCATION ELECTRICAL – LIGHTING LOCATION	NO CLASHES WITH OTHER SERVICES
HVAC SYSTEMS TO BE IN EMERGENCY OPERATION	ARCHITECTURAL – STAIRCASE AND LOBBY DETAILS STRUCTURAL – BEAM LAYOUT	ELECTRICAL- VOLTAGE, CURRENT, PHASE STRUCTURAL – WEIGHT OF OUTDOOR UNITS

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