INTRODUCTION TO HVAC SYSTEM

INTRODUCTION TO HVAC SYSTEM

A typical HVAC system comprises of the heating or cooling producing equipment (boilers, heat pumps etc), pumps and/or fans, piping networks, and heat exchangers transferring or absorbing heat from a space or a process.

The current part of the software is devoted to the analysis of chillers, as a part of an HVAC system. Chillers, in the current work, are defined to be heat pumps (HP) used for cooling, possibly reversible able to produce heat. Studies have shown that about 90% of the energy in an HVAC system is consumed by the chiller/heat pump and the rest 10% by peripheral machinery.

Data for the analysis is drawn from the Eurovent-Cecomaf database. Differences in energy performance between different machines contained in the database are significant and is in the range

Energy performance at full load
Chiller type	EER Min- Max	COP Min- Max
Air cooled	1.61 - 3.97	2.16 - 4.18
Water cooled	2.62 - 6.38	2.33 - 4.94

Energy consumption for cooling is gaining attention during the last years, since it is contributing greatly to the electricity peaks in summer, threatening entire regions with a blackout. A number of studies estimate that air conditioning contributes to peaks in excess of 40%. Heat pumps, on the other hand, are increasingly used for heating in tertiary sector buildings.

Consideration of the energy efficiency parameter in the choice of chillers (heat pumps) is, therefore, of outmost importance.

HVAC is an acronym for - Heating, ventilation and air-conditioning (HVAC) systems are used to provide heated and cooled airflow to a home or business. The cost of an HVAC system installation depends on variables such as the size of the interior space, the number of different zones needed and the complexity of the system.

Function

HVAC systems are designed to supply filtered air that has been conditioned to a certain temperature. HVAC systems supply heated and cooled air to every room of the home or structure and keep it circulating throughout the interior space. In addition to recirculating the interior air, HVAC systems also pull in outside air in order to keep the indoor air fresh.

To function properly, every aspect of an HVAC system needs to be carefully planned and executed. Ductwork needs to be precisely measured and properly sealed to maintain efficiency throughout the system. Supply and return systems help maintain constant pressures within HVAC systems.

Industry Standard

The Air Conditioning Contractors of America (ACCA) designs specifications that all HVAC systems must meet or exceed. HVAC industry standards are set by the ACCA. Proper loads of airflow to individual rooms are determined by ACCA Manual J calculations. The ACCA Manual D can be used to determine a duct system's proper size for a particular home.

Components

There are several main components to any HVAC system, including the air heater or conditioner, a fan, a filter, vents and a series of properly sealed ductwork. The air heater will heat the air that passes through the filter, then a fan forces the air through the ductwork and out the vents. Refrigerants are employed in air-conditioners to cool the air that circulates through a given area. All of the supplemental equipment involved with HVAC systems needs to be properly installed to ensure the system is working at optimal efficiency. Proper drawbands in an HVAC system have a tensile strength of at least 50 pounds and are temperature rated to about 165 degrees Fahrenheit. Quality HVAC systems employ nontoxic sealants that are water-resistant and rated for outdoor use. Galvanized metals are the recommended material for use as ducts and fittings.

Safety

Certain safety measures must be considered during an HVAC system installation. All materials used in an HVAC system must meet ratings dealing with minimum performance temperature, minimum smoke development and minimum flame spreading. If any ductwork is performed, ducts should not come in direct contact with conduit lines, pipes or other metal fixtures.

Thermostat

An HVAC system's thermostat is a very important component of the system. There are thermostats that are ideal for different HVAC systems. Consumers have countless thermostat options to choose from. The most important aspect of an HVAC system's thermostat is its location. A thermostat should be installed about 5 feet up from the ground on a wall in a room that receives regular traffic and relatively decent airflow. Thermostats should not be installed near a vent on in an area that receives too much direct sunlight.

REFERENCES

• Monster Guide: How to Install a Home HVAC Unit
• Air Conditioning Contractors of America: ACCA System Design
• California Energy Commission: Procedures For HVAC System Design and Installation
• Power Vac America: Fresh Outside Air Is a Good Thing