Chapter 5: Types of HVAC Systems

 

Chapter 5: Types of HVAC Systems

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🔹 5.1 Overview

HVAC systems come in various configurations depending on:

Size of the building

Purpose (comfort, industrial, process cooling)
Energy efficiency
Cost and maintenance needs

Understanding different types of HVAC systems helps in selecting the right one for homes, offices, malls, hospitals, etc.

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🔹 5.2 Classification of HVAC Systems

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A. Based on System Location

1. Centralized Systems

One large unit serves multiple rooms/zones.

Requires ductwork to distribute air.

📌 Example:
HVAC plant on the rooftop of a hospital or mall cooling all floors.

✅ Pros:

Energy efficient for large areas

Central control

❌ Cons:

High installation cost

Requires technical operation team

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2. Decentralized Systems

Each room or area has its own unit.

No ductwork required.

📌 Example:
Split ACs in each room of a house.

✅ Pros:

Easy to install and maintain

Individual room control

❌ Cons:

Higher total energy cost in large buildings

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B. Based on Working Principle

1. Direct Expansion (DX) System

Refrigerant directly cools the air.

Used in split ACs, window ACs.

📌 Example:
Split AC in your bedroom.

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2. Chilled Water System

Water is cooled by a chiller and circulated through air handling units (AHUs) to cool air indirectly.

📌 Example:
Chiller plant in an office building or airport.

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C. Based on Functionality

1. Split HVAC System

One outdoor unit and one or more indoor units
Common in homes

Components:

Compressor (outdoor)

Evaporator coil (indoor)
Refrigerant line

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2. Packaged HVAC System

All components packed in one unit.

Placed on roof or ground

Used in:
Small commercial buildings, schools.

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3. Variable Refrigerant Flow (VRF) / Variable Refrigerant Volume (VRV)

Multiple indoor units connected to one outdoor unit

Variable speed compressor adjusts cooling based on need

Used in:
Hotels, large offices, luxury apartments

✅ Pros:

High energy efficiency

Zonal temperature control

❌ Cons:

High initial cost

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4. Hybrid HVAC Systems

Combines two energy sources (e.g., electricity + gas)

Switches automatically based on efficiency

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D. Based on Application

Application Area	Common System Used
Homes	Split, Window, VRF
Small Offices	Packaged Units, Mini-Splits
Large Offices	Chilled Water, VRV Systems
Hospitals	Central HVAC with HEPA filters
Data Centers	Precision Air Conditioning (PAC)
Industries	Air washers, Process cooling units

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🛠️ Practical Example Activities

Visit a mall or hospital and identify whether it's a centralized or VRF system.

Observe how individual offices in a complex may use packaged units.

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🧪 Key System Comparison Table

System Type	Initial Cost	Energy Efficiency	Maintenance	Application
Split AC	Low	Medium	Easy	Homes, Small Shops
Packaged Unit	Medium	Medium	Medium	Medium Offices
Central Chiller	High	High	Complex	Malls, Hospitals
VRF/VRV	High	Very High	Medium	Hotels, High-end Bldgs

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📄 Assignment Questions

1. Define centralized and decentralized HVAC systems with examples.

2. What is the difference between a split AC and a VRF system?

3. Why is a chilled water system preferred in large buildings?

4. List advantages and disadvantages of a packaged HVAC system.

5. Name HVAC systems suitable for hospitals and data centers.

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💼 Interview Questions

1. What is the difference between DX and chilled water systems?

2. How does a VRV system improve energy efficiency?

3. Which HVAC system would you recommend for a hotel? Why?

4. What are the components of a split AC system?

5. Why is central HVAC not suitable for small homes?