Improving The Efficiency & Life of Your Forced Air Heating & Cooling System

Many homes in the United States with forced air heating and cooling have duct work that is old and in need of repair or replacement. Most of these homes have had new furnaces installed over the years, but not the duct work, which would improve the efficiency of new units and keep them running longer. Many houses have duct work that is either too small or too big, installed improperly or not to code and is eating into the efficiency of those new furnace and air conditioning systems.

Here are a few issues we have run into over the years when it comes to forced air heating and cooling systems. These are common installer mistakes or problems in regards to the duct work for heating and air conditioning systems in your home.

Heating and cooling runs off the end cap

When you go into your basement and look at the main trunk line of your duct system, are there heat runs coming off the end caps of your main trunk? If so, this is something that should be checked and more than likely changed.

When your trunk line is not properly capped off, you lose the necessary pressure to send the air flow throughout the rest of the home. If you have lower flows of air in certain rooms of your house, especially upstairs, this could be the reason for those issues. It is a common problem and can be changed by a duct professional who specializes in duct work and sizing your systems. Many times you don't need to replace the whole system because those few runs off the ends of the duct could be re-routed and the main duct capped off at a reduced cost.

Your forced air heat runs may be too small

Over the years the furnace has gone through many changes and so have the methods in which duct work has been installed. Most furnace installations require at least 6" round pipe runs off your main trunk and sometimes larger depending on the furnace unit and size of the home. However, some homes built in the1950's and 1960's were fitted with smaller systems and 4" or 5" heat runs. These runs coupled with today's furnace can present problems with efficiency and life of your new HVAC units.

Increasing those runs to a proper 6" run and checking to make sure your duct is sized properly can help to improve your furnace efficiency and life span. If you are in the process of getting a new heating unit you may want to get a quote for proper sizing and installation of new duct work.

Is the duct system undersized?

Going along with the above tip, some main duct systems are undersized from the start and should be completely replaced to help with efficiency of the furnace. These  systems were either not installed by a professional or the new unit was retrofitted to an already existing duct system that was rated for the previous furnace. The new furnace may either be too big or too small for the existing duct work and because of this, certain rooms in the house my be neglected of proper air flow. This means that you may notice a room is too cool in the winter or too warm in the summer or possibly multiple rooms end up having these same problems. It may be that your duct system needs to be re sized to the new heating or cooling unit you now have installed. Newer units are made to run very efficiently, but an undersized full ducting system can harm the life of your newly installed,  efficient and money saving furnace.


These are a few of the common problems we find when replacing furnaces  in older homes. We will often make note and offer a free quote to the customer for minor changes or complete replacement of their duct system.

Having a brand new efficient, cost cutting forced air heating and cooling unit installed is great for your new or existing home. Recognizing and making sure that your duct system is sized and installed properly can guarantee that your investment will run great for it's lifetime.

For a few examples of our installations click here


Posted on September 13, 2011 and filed under Air Conditioning, Heating, HVAC, Sheet Metal.