The Importance of Correct Supply Grilles
A countless number of times we have been called out to a home where the home owner complains of some rooms not heating or cooling as good as the rest of the home. When we arrive , we find that they have the wrong grille type for the application. This issue can arise for a number of reasons, ( home owner bought the wrong type, grilles were removed for painting/cleaning then not put back in the correct location, or several other reasons.) Having the correct grille type can enhance comfort and efficiency considerably! In this article we will discuss what type and where to put your supply grilles in your home correctly.
The first thing you should do is to make sure that your supply grille damper is all the way open, if you have one. This can be done by simply looking into the turning vanes and see if you have an adjustable damper behind them. If you find one there, open it all the way. Some dampers have a handle to open and close them, while others use a screwdriver slot. Once you have opened the damper all the way, do not forget to re-adjust the turning vanes back to their proper position. If the turning vanes are adjustable, the correct angle for ceiling-type supply grilles are to be adjusted so the air blows across the ceiling to an outside wall. This is where the heat load or heat loss occurs. I have been to many homes where the homeowner has adjusted the vanes to blow air directly down at the floor.
This poses two problems. First, a room will not condition properly unless the air is blowing directly on the heat loss or heat gain area, which is usually an outside wall or window area.The second problem is this. If the air blows right to the floor, there is a good chance that the air will be pulled straight back to the cold air return. This means the conditioned air does not have time to heat or cool the room properly. If you have floor or side wall grilles, the same adjustment rule applies.
Some supply air grilles do not have adjustable vanes or adjustable dampers. In this case, you may need to go to the branch supply duct in the attic or basement and see if you have adjustable volume dampers in the duct. Many duct systems have these adjustable volume dampers, and if your system does, then this is where you need to increase or decrease the airflow to the rooms as needed.
The other way you may adjust for poor air flow , if all else fails, is to add another supply duct or increase the size of the existing supply duct and grille to the room in need. The bottom line on this test is to adjust and balance all supply air grilles as needed to get as close as possible to an evenly cooled or heated home. In some cases, if a room has no cold air return and the nearest cold air return is a long way from this area, you could install a new cold air return to the area with the problem.