Manual J Heat Load Calculation

Manual J Heat Load Calculation

A Manual J Heat Load Calculation is the sure way to determine the proper sizing of your home comfort system. Here is what Energy Star says about the importance of this to determine efficiency: Manual J Heat Load Calculation Energy Star

If this calculation is not brought up by the person you are talking to, ask them why. In most cases, either they do not know how to perform one, or more often than not, they are too lazy to do it. I would insist on one, and if it isn't convenient or they are unwilling to do it, talk with another company. Your system's life can be drastically lowered if the wrong size is installed. Plus you will invest thousands of dollars in it. Why wouldn't you want to know exactly the right size?

This process will take about sixty to ninety minutes but is well worth it. Even if it comes out to the size you already have at least you know for sure the sizing is right and you can use the information later just in case an over-eager salesman wants to upsize or even downsize the proposed unit to just to get the sale or make more money.

Other reasons to have a calculation done is if you have added a room, changed to more efficient windows, added insulation, or other renovations that might affect the amount of air flow or btu requirements.

I have performed heat load calcs on homes that came out as much as a full ton more or less than the commonly accepted "rule of thumb" method the other companies used. This is a huge difference in not only your comfort but also the efficiency of the system, your power bills, and the life of the equipment.

Bottom line: Get a Heat Load Calc--Do it!