August 30, 2011
Should I replace my heating and/or air conditioning system and how do I know?
Probably odds are that sometime in your life you are going to have to consider the question, “should I buy a new air conditioner or should I get by on a repair. Over the next several days we are going to discuss that issue in detail.
So I am going to begin in what some of you may consider to be a strange place—the heat load calculation.
Why start with a heat load calculation you might ask? I thought we were talking about replacing equipment?
The main reason is that proper sizing of equipment is important to your overall comfort not to mention your pocketbook. If your equipment is not properly sized for your current situation, you may be spending a lot more on utility bills than you have to and worse… not getting the comfort that you deserve.
Let's pretend for a moment that you have lived in your house for 15 years, maybe you have some done some remodeling during that time…added 300 or 400 extra square feet. The unit you had when you started may not be adequate for the changes you made.
Most remodels that we see involve extensions of the existing ductwork…not necessarily the best solution.
The purpose of the heat load calculation is to determine the exact size of equipment that is required by your home “under current conditions.”
The easiest way to explain it is to talk about natural laws. Hot air will always seek colder air. When you fill your house with warm air in the wintertime it is always trying to get out your doors and windows…seeking the cooler air. Vice versa in the Summer time the outside hot air is always seeking the indoor air conditioned air.
This movement of air going from the warm air to cool air is called the rate of heat transfer. By considering a number of conditions and measuring them (called a manual J) we can determine the amount of BTU loss or gain. Once we know that information we know it takes an equal amount of BTU’s to replace the amount lost. We can then recommend the correct size of equipment, based on the BTU information, which will be perfect for your house.
Picture for a second a balloon. You inflate the balloon to a certain point and it springs a very small leak. As long as you keep blowing into the balloon at the same rate as the air leaking out it will not deflate.
Same for hot air leaving the house in the winter time. As long as you continue to fill the room with the same amount of BTU’s that it is loosing you house will remain warm and comfortable.
Back to repair replace…if repairing the furnace still leaves you with an undersized furnace and high utility bills…it is probably better to replace.
If you are not sure, give us a call…we will do a free heat load calculation on your home.