If your duct work is older than 15 years, you may want to schedule an inspection.  At 15 years your duct work begins to deteriorate, significantly reducing your HVAC system's efficiency, so replacement is the prudent option.  Ductwork has a maximum lifespan of 20-25 years.

The heating and air conditioning professionals at Hansen A/C will be able to proper replacement size needed based on the size of the home and how far the comfortable air needs to travel from the main unit.  If you install ductwork that is too big, you'll lose the "forced air" effect that helps to keep costs down and maintains the desired efficiency of the unit. 

There are a variety of issues that can warrant the need for ductwork repairs in your home, some of the most common being:

• Damage to supply or return ducts. This could result in leaks and/or harmful emissions being released into your home’s air and should be addressed quickly for the safety of everyone in your home.
• Hot or cold spots around the house. This could indicate a compromised airflow, which could be due to leaks in your ductwork, and can be diagnosed and resolved quickly by your local HVAC professional.
• Damage to internal system components. If you don’t routinely clean your air ducts, the buildup of dust and debris particles can make their way into your HVAC system and damage intricate operational components.