Manuals J, D and S: Is Your HVAC Contractor Going by the Book?Whether you are building a new home or replacing your existing HVAC equipment, it is essential that you choose the right equipment for the job. If your air conditioner or heat pump is too small, it won’t be able to cool your home to a comfortable temperature. If it is too large, you will unnecessarily be spending extra money on capacity that you don’t need. And if the equipment or duct design does not match your home’s specifications, the system will run inefficiently and may cause uneven cooling.You can prevent these problems by choosing an HVAC contractor who uses Manual J, Manual D and Manual S to design the ideal system for your home.

Manual J
Manual J is a procedure used to calculate the amount of cooling or heating needed to bring each room in a building to the ideal indoor temperature. Though originally a printed manual, the modern Manual J is a computer program that calculates the amount of heat that a home absorbs on a hot summer day (or the amount of heat lost on a cold night). It is that amount of heat loss or heat gain that the A/C or heat pump has to overcome to keep your home comfortable.

Manual D
Manual D is used in ductwork design. Based on the Manual J calculations for each room, the ducts can be properly sized and insulated to supply the right amount of air to each part of the house.

Manual S
Manual S is used to select the ideal air conditioner or heat pump for your home’s exact conditions. A model that is highly efficient at moderate temperatures or in a humid climate, for instance, might not be the most efficient choice when installed in Phoenix or Scottsdale.

Many HVAC contractors either don’t know how to properly perform the calculations, or prefer to take shortcuts and use rules of thumb. When choosing a contractor, though, you should find one that doesn’t cut corners. For professional HVAC installation that will keep you comfortable and save you money long-term, contact the experts at Wolff Mechanical.

Our goal is to help educate our customers in the Phoenix Valley area of Arizona about energy and home comfort issues (specific to HVAC systems). 

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