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| HVAC
Heating, ventilating and air-conditioning". This is referred to as climate control.
These three functions are closely interrelated, as they control the temperature and humidity of the air within a building in addition to providing for smoke control, maintaining pressure relationships between spaces, and providing fresh air for occupants. In modern building designs, the design, installation and control systems of these functions are integrated into a single "HVAC" system including the blower, heating and cooling elements, filter racks or chamber, dampers and ductwork through the building.
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| Heating |
Heating is often used in cold climates to heat private houses and public buildings. Such a system contains a central boiler, furnace or heat pump to heat water, steam, or air; piping or ductwork to distribute the heated fluid, and radiators to transfer this heat to the air. The radiators may be mounted on walls, or buried in the floor to give under-floor heating. When so mounted it is often referred to as "radiant heating".The heated water is often fed through another heat exchanger inside a storage cylinder to provide hot running water.
Forced air systems send air through ductwork. During warm weather, the same ductwork can be reused for air conditioning. The forced air can be filtered or put through air cleaners.
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| Air-conditioning |
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An air-conditioning system provides heating, cooling, ventilation and humidity control for a building. It is often installed in modern offices and public buildings, but is difficult to retrofit (install in a building that was not designed to receive it) because of the bulky air ducts required. A duct system must be carefully maintained to prevent the growth of pathogenic bacteria in the ducts. Air-conditioned buildings often have sealed windows, because open windows would disrupt the attempts of the control system to maintain constant air quality.
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| Ventilation |
| Ventilation is the changing of air in any space in order to remove moisture, odors, smoke, heat, and airborne bacteria. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining healthy indoor air quality in a building.
Vntilation may be used to control humidity or odours. Kitchens and bathrooms typically have mechanical ventilation to control both. Factors in the design of such systems include the flow rate (which is a function of the fan speed and exhaust vent size) and noise level. If the ducting for the fans traverse unheated space, the ducting should be insulated as well to prevent condensation on the ducting.
] Heat recovery ventilation systems employ heat exchangers to bring the fresh air temperature to room temperature.
The ventilation is needed when employees are exposed to high toxicity chemicals, when large amounts of dusts or welding fumes are generated, or when increased heating costs from ventilation in cold weather are a concern.
The ventilation operates on the principle that air moves from an area of high pressure to an area of low pressure. The difference in low pressure is created by a fan that draws or sucks air through the ventilation system. Local exhaust systems are located as close as possible to the source of contamination to capture the contaminate before it is released into the work area.
The system has five basic elements:
- A "hood" or opening that captures the contaminant at the source,
- Ducts that transport the airborne chemicals through the system,
- An air cleaning device (not always required) that removes the contaminant from the moving air in the system,
- A fan that moves the air through the system and discharges (blows) it outdoors,
- An exhaust stack through which the contaminated air is discharged.
As with ventilation, makeup air must be provided to replace the air exhausted in order for the system to operate properly.
Figure 1 Components of a local exhaust system.
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| Fans |
Fans are the workhorses of exhaust ventilation systems. They must be the appropriate size and type to make the ventilation system work effectively. They must provide enough air pressure difference ("suction") to capture contaminants at the source, draw them through the hood, carry them through the ducting and exhaust them outdoors.
There are two main types of exhaust fans - axial fans and centrifugal fans. Axial fans draw air straight through the fan. Axial or propeller fans are most commonly used for dilution ventilation or for cooling. These fans are often mounted in a wall or ceiling. They can move large amounts of air if there is little resistance.
Centrifugal fans draw air into the center of the fan and exhaust it at a 90-degree angle. It can operate at against a high resistance and are typically used in local exhaust ventilation systems.
Figure 3. Two types of fans
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| Trouble shooting Services. |
If an existing ventilation system appears to not be functioning properly, the following simple checks can be made:
- Is the fan belt broken or slipping?
- Is the fan wired backward (reversed polarity)?
- Is ductwork clogged with dust?
- Is there holes, cracks or openings in the ducting?
- Is the air cleaner clogged?
- Are any dampers in the ductwork closed?
- Is there insufficient makeup air?
- Has ductwork been changed to include more length, more or sharper bends, or abrupt diameter changes?
- Have employees modified the hood because it interferes with their job tasks?
For all the Trouble shooting services we are always with you. Many of these problems can be avoided by periodic maintenance through AMC.
Contact us by email sales@royalfiltration.com. and visit our web site www.royalfiltration.com
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