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Manual J. – What is it and How is it Used to Size Your Pensacola FL Home?

Published on: June 22, 2012

Because there are no Federal regulations that state exactly what the efficiency level of an air conditioner should be, the AC service industry has had to come up with these regulations and standards on their own. Manual J is the shortened name given to a protocol known as “cooling load calculation” or “heat load calculation”, depending on the season.

Manual J measures exactly how much heat or cooling effort that a living space needs to stay comfortable for the average person in the most extreme two seasons of the year, summer and winter. It is used to size air conditioning and heating equipment so that a living space is not overwhelmed by an inordinately large heating or cooling unit, or underserved by a smaller unit. These calculations are very important for determining the AC system and the air conditioner maintenance that a particular living space needs.

In order to make sure that the AC calls that you have to make are not due to an inappropriately sized HVAC system, you must know the basics about Manual J. Below are some tips about this manual that will save you a great deal of money in AC service and maintenance calls.

1. Bigger does not always mean better when it comes to air conditioning units.

The analogy often given for sizing an air conditioning unit appropriately to a particular living space is that of a commercial performance vehicle and a residential driver. You do not buy a Lamborghini for a trip to the grocery store. This is simply too much power and maintenance required for an average trip.

One of the most important reasons to understand Manual J is to note the standards that have already been calculated from past experience for the size of the heating/cooling equipment that your living space needs. Most people would otherwise get a system that is much bigger than what they need. They would end up spending much more money than necessary on air conditioning maintenance calls.

2. A properly sized system is also needed to promote the best indoor air quality possible.

An oversized system does not allow for a proper dehumidifying of the living space. If an area is not allowed to dehumidify, you can easily create an environment for mold and mildew to flourish. This can cause breathing problems like asthma for people who are overly susceptible to allergens and bacteria, especially children and elderly people.

3. Bigger units do not always mean more comfort in your living space.

If you get a system that is too large for the living space, you may over humidify the space and cause condensation within the rooms. This can lead to many health problems as well as a “wet feeling” that is not comfortable to live with at all. This is perhaps the most important reason to pay special attention to the statistics that a Manual J will give you about your HVAC units.

Below are some of the most important aspects of Manual J in terms of the statistics that it provides you:

Heating load – Manual J will give you the amount of heat that your living space will need on the coldest day of the year. It will give you these figures when you have no help from the sun in order to simulate the most extreme situation possible. You can then use this number to select a proper heating system for your living space.

Block load calculations – Block loads give the total amount of energy that would be necessary to heat or cool your entire living space imagining it as a single room. This statistic is necessary to give you the overall energy that you will need for the entire living space. However, the room by room calculations will give you a more detailed assessment of how much energy you need in each space. This leads directly into the next characteristic that Manual J load calculation will give you.

Room by room load calculations – This statistic will give you the amount of energy that you need to live comfortably in each room of your living space. While the plot of calculation is used to determine size of the total load necessary to heat or cool your living space, the room by room load calculation will give you the balance that will allow you to fine tune the air conditioning for each room in your living space.

Overall, Manual J will give you the detailed statistics for efficient heating and cooling that will save you loads of money on AC service and air conditioner maintenance calls. In addition, it will increase the comfort level of your living space. Make sure that you pay close attention to the findings that a Manual J assessment gives you.