4 Top Methods Of Testing Ducts For Leaks

Even today with HVAC in almost every home, homeowners are not as attentive about a leaky duct as they are about leaky plumbing pipes. It is true damage caused by leaking water from the pipes cause instant and sometimes irretrievable damage to a property. But losses due to leaky duct can also be substernal in the long run. You utility bills wall be way higher than they should be otherwise. Besides this thy will compromise levels of comfort, increase moisture level in the house that will foster molds and other bacteria. Today with increased awareness about indoor air quality, green certification programs have come up that require builders to pay attention to duct tightness. The new building codes are emphasising upon duct testing requirements. There are various methods of testing ducts for airtightness. A professional service of duct cleaning and repair uses four popular methods to check for duct leakage. They are -

• Using only a blower door
• Using a blower door and a pressure pan
• Using a Duct Blaster
• Using a theatrical fog machine

Blower door

This is simplest one. In this two blower-door tests are done-one with the home’s registers sealed with paper and tape, and one without. Subtracting the two readings provides a very rough estimate of total duct leakage. But this test will not give you an accurate result, as a result is avoided in most instances.

Pressure-pan method

Here a pressure pan is used which looks quite similar to a cake baking tray. This connected to a manometer (pressure gauge) with a cable. This used to cover a register of duct and then the pressure exerted on the pan by blower door is calculated.

The pressure of the house is pressurized to 50-Pascal by using a blower door. The air handler is then turned off. The registers are blocked with pressure pan on at a time and then reading of the pressure-pan on the manometer is looked at. If the reading is zero then the duct is not leaking to outside. Higher the reading, the leakier duct.

Duct Blaster test

The most common method for testing the tightness of a duct system is the duct-blower test. All the registers and return grilles are sealed with polyethylene and tape. The air handler fan is turned off. The Duct Blaster is attached to the duct system. The duct blaster is used to increase the pressure of the ducts. The Duct Blaster fan is turned on to force air through the ducts. The fan speed is increased until a standard test pressure is achieved in the duct system. If the duct is able to maintain the pressure that is introduced through the blaster then there are no leaks. But if the pressure goes down then the air is leaking out. The measurement of the leakage is done through airflow and pressure gauge connected to the system.

Testing ducts with a fog machine

In this method all the registers are sealed with tapes and the duct is pressurized. Then a fog machine is introduced in the ducts, aiming the fog nozzle at the fan blades, without letting the fog get drawn into the vent holes in the motor. You have to watch for where the fog pours out. The site where it pours out is a site of leakage.




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