Know About Heat Recovery Ventilation System

Heat recovery ventilation(HRV), also known as mechanical ventilation heat recovery (MVHR), is an energy recovery ventilation system. It makes use of equipments, such as, heat recovery ventilator, heat exchanger and air exchanger. They consist of two ventilation ducts running side ways to one another and each one passing through inside and outside of a house. One carries cool, fresh air in and the other carries moist, stale air out. HRV provides fresh air and also saves energy by reducing the heating requirements. HRV utilizes the counter flow heat exchanger between the incoming and outgoing air flow for effective ventilation.

Heat recovery ventilation devices operates independently. Number or size of the HRV depends on the size of building. In a building, if central HVAC systems are used, then the system would be of the 'forced-air' type.

Energy Recovery Ventilation (ERV), an alternative for HRV works similarly, but transfers some of the moisture from the outgoing airstream into incoming air, helping in keeping the humidity in the home at a constant level, in case if one does not want their home to be too dry.

Advantages of Heat Recovery Ventilation System are:

• They keep the home warm by providing good ventilation. In winter, they can help to save heating bills and in summer, they reduce the need for air conditioning.
• By keeping excess moisture out of the home, they are best for building, furnishings and health and they also help to keep climate at constant level in the home.
• Three quarters of the heat can be retained by the ventilators that would normally be lost from home through ventilation.
• Another advantage of the ventilators is it enhances the efficiency of a building through proper insulation & weather stripping.

Know About Local Exhaust Ventilation(LEV)

Local exhaust ventilation (LEV) is a ventilation system that takes out any dust, mist, gas, vapor or fumes in the air, hence preventing the persons from inhaling the fumes. It is an engineering controlled system capable of preventing airborne contamination which may be harmful for the health. Local exhaust ventilation is used in many areas like laboratories and industrial premises to protect people working from hazardous chemicals. Enclosed hoods or chemical fume hoods vapor or particle generation during pouring operations which involves highly corrosive or reactive chemicals are removed with this system.

To effectively remove pollutants from the workplace and to dispose them off in a safe manner, local exhaust ventilation systems must be maintained in a good working condition. The thorough testing and examination of LEV plants must be carried out for least every 14 months and even more frequently for specific processes.

When applying local exhaust ventilation to a specific problem, there are several basic principles that should be implemented. They are:

• The source of contaminants should be enclosed as completely as practicable.
• Adequate air velocity should be used for capturing of contaminant.
• The contaminant should be kept out of the worker's breathing zone.
• Adequate make-up air must be provided.
• The exhaust air must be discharged away from air inlet systems

If any damage occurs to the LEV, employees must always report so that it can be repaired immediately. The majority of LEV systems need a complete examination and test annually to ensure it still works well and protects employees. More rigorous COSHH testing is required for some high hazard processes.