Ducting
Efficient and properly leak proof ducting is the most important aspect in the installation of Heating,Ventilating and Air conditioning system in a house which actually saves lot of energy and reduces our electrical bills.
Many homeowners may feel that their money is flying right out of their windows, but it may actually be their ductwork that is to blame. An estimated 15 to 30 percent of a home’s total heating and cooling energy is lost through leaky ductwork, costing consumers about $5 billion dollars annually. Lawrence Berkeley National Laboratory has developed a method for internally sealing heating and cooling ducts using a pressurized aerosol sealant. Aerosol duct sealing can reduce duct leakage by up to 90%, reduce energy use by up to 30%. It can also be used on existing homes without moving attic insulation or removing wall and ceiling finishes to gain access to ducts.
Aerosol duct sealing forces vinyl acetate adhesive particles into heating and cooling duct systems via specialized equipment. The adhesive particles are kept suspended by the airflow until they naturally try to exit the duct system through leaks. In the process, particles are flung against the holes where they adhere and build up until the leak is closed.
Savings tend to be greater when air ducts pass through space outside the insulation envelope, such as through attics or crawlspaces.
I have observed that in most of the houses in USA ducts are made in such a way that the air throws through the openings at the floor level and the returns are placed at a height mostly near the ceiling. For distribution of hot air this design is perfectly OK.(as hot air always goes up). But for air conditioning purpose when we need to throw cold air to keep the room temperature down, this system is wrong and need 30 to 35% more energy. Instead, if the system of ducting could be reversed , that means if we could throw the cold air from near the ceiling of the room and take the return near the floor, we would be able to save 30 to 35% energy.This is to be considered at the time of duct design. According to me only by putting a damper just above the air handling unit we would be able to regulate the flow of air. This damper will just reverse the flow during summer.