Ductwork problems can occur even when the ducts themselves are intact and functional. Often the only sign that something's amiss is the noticeable decline of interior comfort.
Neutral air pressure in rooms is the desired state for heating and cooling. This balanced state of affairs happens when air volume entering a room under positive pressure through supply ducts is equivalent to air volume leaving that room through return ducts with slightly negative pressure. Leaks in either the supply or return side of the system disrupt this equilibrium and cause ductwork problems. However, inherent shortfalls in ductwork design when the home was built can also throw things out of whack.
The ideal condition for proper air balance is a dedicated return duct for every area in the house without a clear path for air to travel back to the main return - in bedrooms, for instance. Unfortunately, cost-cutting in construction often limits the number of return ducts. Frequently, multiple supply ducts in different rooms are served by a single central return located in a hallway. Though less than ideal, this system functions as long as the air path between each supply and the central return remains unobstructed.
What goes wrong can be simple: A door is closed. Supply air entering that room now has no path to the return. A state of positive air pressure results inside the room, pushing conditioned air out through every crack and gap in the structure. Room temperatures become inconsistent and the A/C or furnace runs longer. Meanwhile, with the air supplied to that room subtracted from the total volume of air returned to the air handler, negative pressure occurs in the rest of the house. Unconditioned hot or cold outdoor air is sucked into the structure, further disrupting temperature and comfort control.
When a dedicated return for each supply duct isn't feasible, ductwork problems can be prevented by installing air pass-through grilles in room doors or jumper ducts in ceilings to make sure supply air always has an unobstructed path to the return.
For more information about your home's ductwork problems, or for any other HVAC issue you may be facing, contact the pros at Jon Wayne Heating & Air Conditioning. We're proud to serve San Antonio homeowners.
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