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The seal of efficiency

Since duct-leakage issues have a direct bearing on the comfort level of occupants, the problems need to be addressed promptly, says Billy Prewitt.

| | Sep 16, 2012 | 2:45 pm
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Since duct-leakage issues have a direct bearing on the comfort level of occupants, the problems need to be addressed promptly, says Billy Prewitt.

Occupant comfort in a commercial facility plays a critical role in productivity, because productivity goes down if the occupants are not comfortable. Therefore, the onus lies on facility managers to identify the root cause of thermal comfort issues and ensure that repairs are carried out effectively.

Leakage in the ducts affects the HVAC system and, in turn, affects occupant comfort and, therefore, must be addressed immediately. However, the general tendency is to speed up fans, change motors and carry out other similar inconsequential changes to the system when occupants complain of discomfort. These changes are not only ineffective but also costly, as they demand labour and equipment upgrades as well as additional energy. Another factor to be considered is that if leakage issues are not immediately and effectively addressed, occupants might take matters into their own hands and press into service fans or heaters or hijack thermostats.

In the light of this, validation of recommended repairs is especially relevant to thermal comfort issues in a building. Identifying the real problem is the first step towards having a truly efficient comfort system. Testing the HVAC ductwork in both new construction and existing structures can be completed in various ways. One suggested method would be to use a duct leakage tester. This device positively pressurises the ductwork and, then, measures the amount of leakage at the specific pressure. Another option to test for leakage would be to use a smoke machine. This visual confirmation allows leakage to be pinpointed and patched. Some use a soapy solution on areas that are potentially susceptible to leaks. It needs to be noted that duct leakage is a given, and testing will expedite the proper system repair.

Justifying the expense for repairing a leaking duct system is made easier by using standard airflow calculations. There is an online program available which allows users to calculate the energy savings from a one- to 20-year period. The calculations involve multiple inputs, such as building square footage, local utility rates, and leakage before and after sealing. This program allows a facility manager to see the benefits of tightening up the ductwork without extensive mechanical system and airflow. The climate and location of buildings play a big role in the discernible cost and energy savings. The more diverse the temperature changes, the greater the potential cost savings will be.

Many of the comfort issues of occupants can be solved if the root problem of duct leakage is addressed. Testing the ductwork for leakage is the first step in solving this overwhelming system challenge. Once the leakage is detected and evaluated, sealing the ducts and re-balancing the system can be done, which will lead to increased occupant comfort and energy savings.

Taking into consideration the vital role played by ducts, it is important to address complaints promptly and test the ductwork for leakage and completely seal the system. Testing and sealing the ducts in a building will lead to a truly efficient HVAC system.

The writer is Marketing Manager, Carlisle HVAC. He can be contacted at Billy.Prewitt@CarlisleHVAC.com

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