ACCA Manual J Sizing

Air Conditioning Contractors of AmericaWhen a new home is built, or an addition is being considered, at some point during the planning stage someone needs to figure how much heating or cooling energy will be required for the new structure. Manual J is the industry standard residential load calculation method, required by most building codes around the country. Typically your HVAC installer will perform this task on their own. We can offer this service to those who:

You want to create a level playing ground to acquire several bids
You're not sure if your home has the appropriate system installed
You're in the cross fire between and builder and a HVAC contractor

There are several popular software vendors out there, with Elite and Wrightsoft being the leaders of the pack. Our company uses both of these programs; more often the Wrightsoft version because of its clear and easy to navigate drawing module.

Like any software, often times the user doesn't utilize the full potential of the program. In an effort to maximize efficiency and accuracy, Wilson Services, Inc. has acquired training with this program twice.

What most every computer user understands is simply good information going in means good information will come out. Unfortunately, there are several aspects that still need to be guessed at. The only real information will be room sizes, window sizes, suns orientation for AC loads, and insulation that we can actually see. Many contractors will guess at the infiltration, which may or may not be accurate (please see our Blower Door section of this site).

Wilson's sales staff will perform this calculation before every new complete system is installed. Don't be tricked into thinking its the last word in energy delivery. As mentioned above, there are a number of factors that can be adjusted to manipulate the numbers.

Here is some food for thought: Before our company started doing calculations, we would have the vendors do this for us. This may not shock the average consumer, or the average HVAC contractor, but we were finding the materials being presented to us from our vendors were a bit larger than necessary. This provides several problems. If the stuff cost us more, you bet its going to cost the end-user more. And if its oversized, do you think it will run as efficiently? No it will not. So, if you're out there talking with HVAC contractors and you see that they're bringing in other folks to help them design the system, you may want to wonder why.

Sadly, our society has some real trouble when it comes to buying things. Let me be a bit more specific: Our get as much as we can for as little as possible antennas are always looking for the best deal. Where you'll regret this method of commerce if when you're face to face with an HVAC contractor, and he's recommending one system for one price, and the next guy that comes in is recommending a slightly larger system for a lower price. Ahh, can you resist the temptation? Can you dig down and really spend more money for a smaller system? Doesn't it go against every morsel of wisdom that we've ever been taught?

Because we just opened Pandora's Box here, well need to touch on some basic items: The size of the system and the selling price of the installation.