HVAC

HVAC (Heating, Ventilation, and Air Conditioning) is an important aspect of building design and construction. The Central Public Works Department (CPWD) has developed guidelines for HVAC systems in buildings to ensure comfortable and healthy indoor environments. Here are some of the key points from CPWD guidelines for HVAC:

1. Heating: Heating systems are designed to maintain a comfortable indoor temperature during cold weather. The CPWD guidelines recommend the use of energy-efficient heating systems, such as heat pumps and solar water heating systems, to reduce energy consumption and environmental impact.

2. Ventilation: Ventilation systems are designed to provide fresh air and remove stale air from the building. The CPWD guidelines recommend the use of natural ventilation systems wherever possible, such as windows and louvers, to reduce energy consumption. However, mechanical ventilation systems may be required in certain situations, such as buildings with high occupancy or air pollution.

3. Air Conditioning: Air conditioning systems are designed to maintain a comfortable indoor temperature during hot weather. The CPWD guidelines recommend the use of energy-efficient air conditioning systems, such as variable refrigerant flow (VRF) systems and evaporative cooling systems, to reduce energy consumption and environmental impact.

4. Ducting and Insulation: The CPWD guidelines recommend the use of properly insulated ducts to reduce heat loss and ensure efficient air distribution. The ducts should also be properly sealed to prevent air leakage, which can reduce the efficiency of the HVAC system.

5. Controls and Automation: The CPWD guidelines recommend the use of energy-efficient controls and automation systems to optimize HVAC system performance. These systems can monitor indoor and outdoor temperatures and adjust the HVAC system accordingly to reduce energy consumption.

   
   
   

In summary, the CPWD guidelines for HVAC systems focus on energy efficiency, indoor air quality, and occupant comfort. The guidelines provide recommendations for heating, ventilation, air conditioning, ducting and insulation, and controls and automation to ensure an efficient and effective HVAC system for buildings.

 

Working Principle of HVAC:

The working principle of HVAC (Heating, Ventilation, and Air Conditioning) systems is based on the principles of thermodynamics and fluid mechanics. Here's a brief overview of the working principle of HVAC systems:

1. Heating: Heating systems work by transferring heat from a source (such as a furnace or heat pump) to the air or water that circulates throughout the building. The heated air or water is then distributed through ducts or pipes to maintain a comfortable indoor temperature.

2. Ventilation: Ventilation systems work by bringing in fresh air from outside and removing stale air from the building. This is important for maintaining good indoor air quality and preventing the buildup of pollutants, such as carbon dioxide and volatile organic compounds.

3. Air Conditioning: Air conditioning systems work by removing heat and moisture from the air inside the building and transferring it outside. This is typically done using a refrigeration cycle, which compresses and expands a refrigerant gas to absorb and release heat.

4. Ducting and Insulation: Ducts and insulation play an important role in the efficiency of HVAC systems. Ducts are used to distribute air throughout the building, while insulation helps to prevent heat loss or gain. Properly sized and insulated ducts can help to reduce energy consumption and improve the overall performance of the HVAC system.

5. Controls and Automation: Controls and automation systems can help to optimize the performance of HVAC systems by monitoring indoor and outdoor temperatures, humidity levels, and other factors. This information is used to adjust the heating, ventilation, and air conditioning systems to maintain a comfortable and healthy indoor environment while minimizing energy consumption.

In summary, HVAC systems work by transferring heat, removing moisture and pollutants, and distributing conditioned air throughout a building. The specific working principles depend on the type of HVAC system and the components used, but they are all designed to maintain a comfortable and healthy indoor environment while minimizing energy consumption.

HVAC Equipment's:

A. VRF/VRV Air-Conditioning System

                OUTDOOR UNIT

Modular type Variable Refrigerant Flow/Variable Refrigerant Volume air cooled Outdoor units suitable for cooling and heating, having all hermetically sealed inverter type Scroll Compressor(s), minimum two compressors for above 14 HP modules, microprocessor based Controller, top discharge type condensing unit(s), with R 410 A Refrigerant, vibration isolators, with suitable foundation etc. complete as required. The unit shall deliver the rated capacity at AHRI Conditions and work even at 50°C ambient temperature without tripping. The unit shall be suitable to work on 400V +/- 10%, 3 Phase, 50Hz AC power supply. The unit shall be filled with first charge of the refrigerant and ready for use as required. The COP at AHRI conditions shall not be less than 3.1 and IEER not less than 6.5 .

INDOOR UNIT-CASSETTE TYPE

Minimum capacity 4-way flow VRV/VRF Cassette Type Indoor ceiling mounted unit equipped with synthetic washable media pre-filter, fan section with low noise fan/dynamically balanced blower, multispeed motor, coil section with DX Copper coil, electronic expansion valve, outer cabinet, drain pump, grill, necessary supports, vibration isolation, cord less remote control etc., suitable for operation on single phase 230 V ± 10%, 50Hz AC supply, complete, as required. The unit shall have automatic force shut down provision in case of fire on receiving signal from BMS System. The cooling capacity of indoor unit will be at air inlet conditions of 27 Degree C DB and 19 Degree C WB temperature.

INDOOR UNIT-HIGH WALL TYPE

Minimum capacity VRV/VRF High wall type Indoor unit equipped with washable synthetic media pre-filter, fan section with low noise fan/dynamically balanced blower, multispeed motor, coil section with DX copper coil, electronic expansion valve, outer cabinet, cord less remote control, drain pan, necessary accessories etc., suitable for operation on 230 V ± 10%, 50 Hz, single phase AC supply, complete as required. The unit shall have automatic force shut down provision in case of fire on receiving signal from BMS System. The cooling capacity of indoor unit will be at air inlet conditions of 27 Degree C DB and 19 Degree C WB temperature.

INDOOR UNIT-DUCTABLE TYPE

Minimum capacity and external static pressure VRF/VRV ceiling mounted ductable type Indoor unit equipped with washable synthetic media pre-filter, fan section with low noise fan/dynamically balanced blower, multispeed motor, coil section with DX copper coil, electronic expansion valve, corded remote control, outer cabinet, vibration isolators, drain pan, other necessary supports etc., suitable for operation on single phase AC supply 230 V ± 10%, 50 Hz complete as required. The unit shall have automatic force shut down provision in case of fire on receiveing signal from BMS System. The cooling capacity of indoor unit will be at air inlet conditions of 27 Degree C DB and 19 Degree C WB temperature.

Low static ductable units (minimum 25 pascal external static pressure)

Mid Static Ductable units (minimum 45 pascal external static pressure)

High Static Ductable units (minimum 110 pascal external static pressure)

COPEER REFRIGERANT PIPING

Including vaccumiazation and Nitrogen testing of following nominal sizes of soft/hard drawn copper refrigerant piping for VRV/VRF system, complete with fittings, with suitable adjustable ring type hanger supports, jointing/brazing including accessories, insulated with XPLE Class-O tubular insulation/with Class-O closed cell elastometric nitrile rubber tubular sleeves sections of specified thickness as given below for Suction and Liquid lines, all accessories as per specifications etc. as required :

19 mm thick insulation

NOTE:-

1)The Copper Piping & Piping Circuit should be with Minimum Number of joints, which shall be attained by :

(i) Using One End Expanded Tubes

(ii) Bending the tubes instead of using elbow joints wherever 90 degree bending is required.

(2) Piping should be routed at site in such a manner, that brazed joints in the refrigeration piping are kept to a minimum.

(3) The makes of tube fittings shall be same as that of tubes.

(4) The thickness of fittings used shall be same as that of the pipe.

 

Cartage @1%

ITC @4%

B. HVAC (Heating, Ventilation, and Air Conditioning) systems use a variety of equipment to perform their functions. Here are some of the common equipment used in HVAC systems:

1. Heating Equipment:

• Furnaces
• Boilers
• Heat pumps
• Electric resistance heaters
• Radiant heaters

2. Cooling Equipment:

• Air conditioners
• Chillers
• Evaporative coolers
• Heat pumps

3. Ventilation Equipment:

• Exhaust fans
• Intake fans
• Air handlers
• Air purifiers
• Humidifiers and dehumidifiers

4. Ducting and Insulation:

• Ducts and duct fittings
• Dampers
• Filters
• Grilles and registers
• Insulation materials (such as fiberglass, foam, and cellulose)

5. Controls and Automation:

• Thermostats
• Sensors (such as temperature, humidity, and occupancy sensors)
• Control panels
• Programmable logic controllers (PLCs)
• Building automation systems (BAS)

Some more Equipment's are

1. Piping:

• Pipes (such as copper, steel, and plastic)
• Fittings (such as elbows, tees, and reducers)
• Valves (such as ball valves, gate valves, and butterfly valves)
• Expansion tanks

2. Refrigeration Equipment:

• Compressors
• Condensers
• Evaporators
• Refrigerant piping and fittings

3. Controls and Automation:

• Variable frequency drives (VFDs)
• Pressure sensors
• Flow sensors
• Temperature sensors
• Actuators (such as damper actuators and valve actuators)

4. Energy Recovery Equipment:

• Heat exchangers (such as air-to-air heat exchangers and heat recovery ventilators)
• Energy recovery wheels
• Desiccant dehumidifiers

5. Renewable Energy Equipment:

• Solar collectors
• Geothermal heat pumps
• Wind turbines

These equipment are used in various combinations to provide heating, cooling, ventilation, and air quality control in buildings. The selection and design of HVAC equipment depends on many factors such as the building type, the location, the climate, the energy efficiency goals, and the budget.

In addition to these equipment, HVAC systems may also use pumps, valves, and other components to circulate fluids (such as water and refrigerants) and control the flow of air and water. The specific equipment used in an HVAC system depends on factors such as the size of the building, the climate, and the desired level of comfort and energy efficiency.

Testing of HVAC:

CPWD (Central Public Works Department) provides guidelines for testing and commissioning of HVAC (Heating, Ventilation, and Air Conditioning) systems in buildings. The testing procedures are designed to ensure that the HVAC systems are installed and functioning correctly, and that they meet the required standards and specifications. Here are some of the testing procedures recommended by CPWD for HVAC systems:

1. Pre-Commissioning Checks:

• Verify that all HVAC equipment is installed as per the approved drawings and specifications.
• Check that the electrical connections are correct and all controls are functioning.
• Inspect the ductwork, piping, and insulation for leaks, damage, and proper support.
• Test all equipment for proper operation and performance.

2. Airflow Testing:

• Measure and record the airflow rates in each duct section.
• Verify that the airflow rates meet the design specifications.
• Check the air balance between supply and return air systems.

3. Temperature and Humidity Testing:

• Measure and record the temperatures and humidity levels in each zone.
• Verify that the temperatures and humidity levels meet the design specifications.
• Check for temperature stratification and adjust the airflow as necessary.

4. Noise Testing:

• Measure and record the sound levels in each zone.
• Verify that the sound levels meet the design specifications.
• Identify any sources of excessive noise and take corrective action.

5. Energy Efficiency Testing:

• Measure and record the energy consumption of each HVAC equipment.
• Verify that the energy consumption meets the design specifications.
• Identify any areas where energy savings can be achieved and take corrective action.

6. Commissioning Report:

• Prepare a commissioning report that documents the results of all tests and inspections.
• Include any issues found during the testing and the corrective actions taken.
• Verify that the HVAC system is ready for operation and handover to the owner.

These testing procedures are designed to ensure that HVAC systems are functioning correctly and efficiently, and that they provide the required comfort and air quality for building occupants. Proper testing and commissioning of HVAC systems can help to reduce energy consumption, prevent equipment failures, and extend the lifespan of the equipment.

AIR CONDITIONING SYSTEM (HVAC)
Sl. No.	Work to be Execute	Area	Description
1	1st	Typical  Floor	Duct hangers & Supports
2			Chilled Water Pipe Hangers & Supports
3	2nd	Typical  Floor	Ducting Supply, return, Fresh & Exhaust
4			Volume, Fire & Smoke Damper Fixing
5			Duct Risers
6			Duct Insulation
7			Chilled Water Piping
8			Chilled Water Pipe Riser
9			Chilled Water Pipe Test
10			Chilled Water Pipe Insulation
11			FCU Installation
12			Duct Connection to FCU
13			Pipe Connection to FCU
14			Bends, Droppers & Mouth Piece
15		Basement/ Mechanical Floor	Chillers Installation
16			Heat Exchanger Installation
17			Staircase Pressure Fan Installation
18			Garbage Exhaust Fan Installation
19			Chilled Water Pump Installation
20			Expansion Tank & Pressure Unit Installation
21			Air Scrubbers installation
22			Chemical Dozing Plant Installation
23			AHU Installation
24			Duct Connection to AHU
25			Pipe Connection to AHU
26	Final	Typical  Floor	Kitchen Exhaust Fan Fixing
27			Ceiling Diffuser Fixing
28			Grille & Linear Fixing
29			Thermostat Fixing
30	Testing & Pre-Commissioning		Pre commissioning chilled water pumps
31			Water circulation in system and drain (Static)
32			Circulation of water with cleaning chemical
33			Pre commissioning FAHU's
34			Cleaning of all filters and strainers
35			Pre commissioning pressurization fans
36			Water circulation in system and drain (dynamic)
37			Refilling of water and witness by Engineer
38			Prelim. Adjusting and balancing of valves
39	Commissioning & Handover		Test and commission chilled water pumps
40			Test and commission heat exchangers
41			Test and commission FAHU's
42			Test and commission floor FCU's
43			FAHU air balancing
44			Air balancing supply & return grilles
45			FCU water balancing
46			Balancing air from pressurization fans
47			Water balancing of FAHU's
48			Main System Valves adjustment

 

MECHANICAL FLOOR / ROOF ACTIVITIES
Sl. No.	Activity Description
1	Chillers Installation
2	Heat Exchanger Installation
3	Staircase Pressure Fan Installation
4	Garbage Exhaust Fan Installation
5	Chilled Water Pump Installation
6	Expansion Tank & Pressure Unit Installation
7	Air Scrubbers installation
8	Chemical Dozing Plant Installation
9	AHU Installation
10	FCU Installation
11	MCC Installation
12	Booster Pump Installation
13	Water Tank Installation

 

 

LIST OF TESTING AND COMMISSIONING ACTIVITIES HVAC
Sl. No.	Activity Description
1	Pre commissioning FAHU's
2	Cleaning of all filters and strainers
3	Pre commissioning pressurization fans
4	Water circulation in system and drain (dynamic)
5	Refilling of water and witness by Engineer
6	Prelim. Adjusting and balancing of valves
7	Test and commission chilled water pumps
8	Test and commission heat exchangers
9	Test and commission pressurization fans
10	Test and commission FAHU's
11	Test and commission floor FCU's
12	FAHU air balancing
13	Toilet exhaust / kitchen exhaust air balancing
14	Air balancing supply & return grilles
15	FCU water balancing
16	Balancing air from pressurization fans
17	Water balancing of FAHU's
18	Main System Valves adjustment

Some of the key IS codes and standards that are relevant to HVAC systems as per CPWD specifications are:

1. IS 13299 - Code of practice for air conditioning systems.
2. IS 15211 - Method of testing for performance of air conditioning and ventilation units.
3. IS 16816 - Code of practice for energy-efficient operation of buildings.