Contractingbusiness 907 13897ctech0100j00000006753

Calculating Loads: A Contractor's Best Friend

April 1, 2006
BY KENNY WATSON table width="200" border="0" align="right" cellpadding="5" cellspacing="0"div align="center"img src="/images/archive/13897ctech0100j_00000006753.jpg"


A properly calculated load eliminates guessing and safety factors when it comes time to choose equipment for an HVAC system. Installing correctly sized equipment reduces cost, extends equipment life, and increases your company's profit.

Simple, correct equipment sizing can be all the edge a contractor needs in today's competitive HVAC market. Fortunately, there's a simple, cost effective process for determining load calculation — the new ACCA Manual J8 Abridged Version (MJ8ae).

Why Should You Calculate Loads?
You may be wondering what the advantages are to calculating loads. The answer is simple: proper load calculation reduces your competition, increases your competitiveness, expands your customer value perception, grows your customer confidence, builds your professional image, improves your sales closure rate, and provides upgrade opportunities.

Most contractors don't run loads. Therefore, when you run a load, it repositions other contractors as merely bidders. Because you are calculating a detailed load, you are involving the customers and addressing their individual lifestyle and comfort desires. You aren't just selling them a system; you are involving them in the process of designing it.

Involving the Homeowner
Sales experts tell us that asking the right questions can be the most potent part of sales because it helps build trust with the customer. However, sometimes homeowners don't know when to ask questions.

Involving them in the design process is an integral part of making the sale. As you go through the discovery — or information gathering — process with the homeowner, you impress upon them that you are knowledgeable and will provide them opportunities to ask questions.

Running load calculations also educates the homeowner on the value of the load.

This assures them that the equipment they select will provide comfort, which grows their confidence and value perception of your company.

By going through the design process with you, the homeowner sees the amount of time you invested in gathering details. They're also more willing to listen to you about recommended upgrades and improvements to their system.

Attaining the knowledge it takes to properly calculate a load isn't as difficult as it seems.

What is MJ8ae?
In the residential design process, a room-byroom, or a block load, calculation is performed before other processes, such as equipment selection (Manual S), duct design (Manual S), and room air distribution (Manual T).

MJ8ae is a resource that outlines this process, dividing it into three sections: the Procedure, the How, and the Why. The Procedure portion covers the mechanics involved with load calculations. The How portion outlines the step-by-step directions on how to complete the procedure, and the Why portion contains all the supporting information that explains the various bodies of knowledge that the procedure is built upon.

This abridged version is the most recent evolution of Manual J. Unlike its predecessors, Version 8 is loaded with information on today's construction methods and materials, and is very heavy on procedures.

Uses for MJ8ae
Basic knowledge is a necessary foundation to performing a load calculation. MJ8ae contains a glossary of terms as well as program aids for measurement skills, understanding architectural floor plans, math skills, understanding design conditions, and window fundamentals.

In addition to being a guide for calculating load size, it is a tool that can be used for troubleshooting system design problems, such as design concept/application compatibility, under sizing issues, over sizing issues, humidity control issues, and part load performance issues.

A Useful Tool
MJ8ae has a three-page table of contents and an eight-page index, making it very easy to navigate. The software is contractor friendly and condenses all the information in the full version of MJ8, focusing more on the How and Why. For contractors who use computer assisted system design, it is an ideal resource manual.

Included with MJ8ae is an electronic workbook in Microsoft Excel that makes load calculations even easier. Just plug in some measurements and data, and the workbook calculates the load based on the specifications.

Using the information contained in MJ8ae to calculate loads allows you to offer homeowners equipment options best suited to giving them just the right amount of conditioned air to space. It's an efficiency and comfort issue that homeowners understand and appreciate.

The Choice is Clear
When your competition doesn't calculate a load, they can't provide the homeowner with a guarantee of energy reduction and longer equipment life. You can; it's the difference between knowing and guessing.

A properly calculated load communicates to the homeowner that you're doing it right. It builds your professional image and confidence, because you now have a knowledge foundation when it comes to equipment selection, duct design, and register/grill selection.

Homeowners like to have choices. Calculating loads while designing a comfort system makes you look more professional than your competition. The choice is clear to the homeowner; everyone prefers to deal with a professional.

Kenny Watson is a 30-year veteran in the HVAC industry. He has served in various capacities during his career and currently works as operations manager for Roscoe Brown, Inc., a large mechanical contracting firm located in Murfreesboro, TN. Kenny serves as a member of the ACCA Manual J Review Committee, and also developed the Microsoft excel version of MJ8ae, an electronic workbook for load calculation. For more information, visit