Proper residential HVAC sizing is directly related to a HVAC contractor understanding and utilizing the information provided by ACCA certified Manual J8 load calculations. The data provided by these reports enable a skilled and competent contractor to determine the correct size and design of an HVA C system in order to deliver the best possible comfort for a home or while obtaining the greatest possible utility savings. Contractors who do not use these types of calculations often mistakenly install comfort equipment that is undersized or, more often, too large. This creates a comfortsystem that is not energy efficient as well as expensive for the homeowner.

It is very important to size the comfort unit properly. If the unit is undersized, it will not condition the house fast enough, on the other hand, if it is oversized, it will condition the house too fast without properly dehumidifying the room. Often contractors use "rules-of-thumb" to figure out the size of the heating unit, without considering some important variables such as, the internal heat gain and loss, moisture content, building orientation, ventilation and infiltration, resulting an overly-sized furnace.

HVAC design should be dependent on the needs of the particular building or home. This means installing a comfort system that works in the most effective way possible while using the least amount of energy than is absolutely necessary. A system that is too small will have to run continuously and will be subject to frequent breakdowns and repairs. If a system is too large, the temperature inside the house is likely to vary widely as well as have a moist or clammy feel to it. An oversize system is also likely to require more frequent maintenance since it will be running much less efficiently.

The data provided by ACCA Manual J reports will also make it easier for a contractor to properly design and install the duct system. Manual D duct design is used by competent HVAC installers to install ductwork that provides exactly the right amount of cfm to each room of the house. This ensures that no room is getting too much or too little heated or cooled air. By evenly heating and cooling a home a system is able to operate much more effectively. The duct design plays a large role in how well a comfort system performs.

Manual S equipment selection is also impacted by Manual J reports. By hiring a contractor who understands and uses this type of trusted calculating and reporting system, a homeowner can rest assure that the individual installing their HVAC system is competent and qualified to deliver excellent results. A system that operates efficiently uses less energy which means it is more economical to run over time. Those are the kinds of results that every homeowner is hoping to achieve when they upgrade or replace their HVAC system. The information provided by Manual J reports can help a contractor install a system that will provide years of trouble free and reliable results.