HVAC | What is HVAC | HVAC Overview | Heating, Ventilation, Air conditioning | HVAC operation and trouble shooting

HVAC

What is HVAC?

• Heating, Ventilation, Air conditioning
• Controls temperature, humidity and air quality inside a building
• Especially important in medium to large buildings such as office/residential towers
• All preferably integrated into one system
• In warm climates usually no need for a heating system

1.) Heating:-

• Central heating often used in cold climates to heat private houses and public buildings.
• Heating systems usually comprise of a boiler, furnace, heat pump or district hot water to heat water, steam or air.
• Piping distributes heated fluid and radiators transfer this heat to air and structures, e.g. floor heating system.

2.) Ventilation:-

• The process of ”changing” or replacing air in any space to control temperature or remove moisture, smoke, carbon dioxide, etc
• Ventilation includes both the exchange of air to the outside as well as circulation of air within the building.
• One of the most important factors for maintaining acceptable indoor air quality in buildings.
• Supply air used for ventilation is filtered and cooled and/or heated inside air handling units.

3.) Air conditioning:-

• Refers to the cooling and dehumidification of indoor air for thermal comfort.
• Air conditioning systems are designed to stabilize the air temperature and humidity within an area.
• Excess heat from the circulating air is usually removed by a cooling coil that is supplied with cold water.
• To decrease relative humidity the circulating air needs to be cooled to a temperature below the dew point and then heated back to meet the requirement.

Major terms of HVAC

1. Air handling unit (AHU) – a central unit consisting of a blower, heating and cooling elements, filters, etc. that are in direct contact with the airflow.
2. Chiller – a device that removes heat from a liquid .The cooled liquid flows through pipes and passes through coils in air handling units, FCUs, etc
3. Coil – equipment that performs heat transfer inside an AHU etc.
4. Damper – a plate or gate placed in a duct to control airflow.

HVAC Components

HVAC operation and trouble shooting

1.) Low Suction Pressure:-

BELOW 10 PSI

1. Check suction water pressure. It should be above parameter
2. Check parameters setting Gas pressure-                                                                          Static- 90-110 PSI      Running- 25-30 PSI
3. Check sensor feedback. It should between 4 to 20 mA.
4. Expansion valve to be check working or not 1) Direct supply and battery supply to be healthy -11-18V.

2.) High Discharge Pressure:-

ABOVE 260PSI

1. Condensate fan to be check running or not (relay to be check)
2. Check discharge pressure. It should be lower then parameter setting
3. Fin cleaning to be done
4. Parameters to be check
5. Sensor to be check (suction and dis.)
6. Check sensor feedback. It should between 4 to 30 mA.
7. Check polarity it should be as per sensor drawing

3.) Zone -B:-

75% and above 240 PSI for 1 min.

1. Condensate fin to be check for cleaning
2. Refrigerant pr. To be check according to ambient                                                                Static- 90-110 PSI               Running – 25-30 PSI
3. Expansion valve to be check working or not 1) Direct supply and battery supply to be healthy -11-18V.

4.) Zone -F:-

100%  load for 1 min.

1. Condensate fin to be check for cleaning
2. Refrigerant pr. To be check according to ambient                                                                  Static- 90-110 PSI            Running – 25-30 PSI
3. Expansion valve to be check working or not 1) Direct supply and battery supply to be healthy -11-18V.