A clean air conveyance system is a benchmark for good indoor air quality (IAQ). But how do you know when you need duct cleaning? After all the ductwork in a facility is out of sight and typically out of mind. Unless you periodically take a look inside of the ducts you would never know they are dirty. So, let’s take a look at quick 3 factors that help determine if you need duct cleaning.

1. Dusty Supply Registers and Filters

One of the easiest ways to assess the conditions inside the ducts is to pay attention to the areas outside of them. Ductwork is dirty when there is a buildup of dust on the supply registers. Dirty supply registers also mean that the dust is being distributed into the occupied space. When you notice a dusty supply register it’s a good idea to take it off and have a look inside. If there is excessive dust and debris within the supply run, you need duct cleaning.

Be sure to check your filters regularly, too. Dirty filters choke the return air supply. Therefore, the returning air looks for the path of least resistance to be recirculated through the system. This is known as filter bypass. So, the unfiltered air is returned to the air handling unit (AHU) where it fouls the blower, coils and other HVAC components. Of course, this creates other issues for the equipment, besides redistributing the dust through the system.

What is in building dust?

Building dust is comprised of many different materials found in both the outside and indoor environment. Nearly two thirds dust is from the outdoors. It is dirt tracked in or are airborne particles like pollen. The rest is made up of human skin cells, manmade/natural fibers, animal hairs, insect detritus, and various particles. Recent building renovations also contributes to the mix, as well.

The Coanda Effect

A major factor that contributes to dusty supply registers and ceiling streaking is the Coanda Effect. Basically, airflow from the register/diffuser creates a pressure zone between the diffuser surface and the ceiling. This allows the conditioned air to travel along the ceiling and be distributed farther into the room. The Coanda Effect plays a role in ceiling smudging in three ways. 1. The streaking is from dust coming out of the ducts. 2. Dust is picked up from within the room in a low velocity pocket and put on the ceiling. 3. Dust is infiltrating from unsealed openings where ductwork supply boot penetrations are made. So, while ceiling streaking still might indicate you need duct cleaning, housekeeping and the building envelope should be checked as well.

2. Large Particulates

Another sign that you need duct cleaning is when you find large particulates falling and collecting on surfaces beneath the supply registers. Believe it or not, this happens more than you think. Usually this debris is in the form of small fragments or round shapes. It’s bigger and harder than dust. Often it is darker in color too. Generally, large particulates are pieces of fiberglass insulation, duct board, or clumps of dust. They get dislodged downstream from the coil in the supply line and blown through the registers. If there are VAV terminals inline they can easily become fouled with this debris.

If you observe large particulates collecting under the supply registers check the AHU, supply plenums and supply ductwork immediately. Besides a thorough cleaning, degraded insulation and duct board will need to be encapsulated or replaced.

3. Occupant Complaints

Finally, pay attention to your building’s occupants. When there is a pattern of similar complaints originating from a specific area dirty ducts might be to blame. Take the complaints seriously and survey the occupants’ symptoms. Often, they are experiencing allergy symptoms like headaches, nasal congestion or watery eyes. Sometimes it’s more elevated with shortness of breath of more frequent asthma attacks.

The U.S. EPA estimated that 1 in 6 building occupants suffer allergies from allergens, bacteria and fungi distributed by the HVAC system. This has a tremendous negative effect on productivity and morale. Occupant complaints is a good sign you need duct cleaning. Moreover, the affected area and system should also be tested to determine if there is mold or allergens and in what quantity. If mold is present it will require deep cleaning from a certified Ventilation System Mold Remediator (VSMR) to ensure a safe outcome.

Need Duct Cleaning or Testing?

Pure Air Control Services is an IAQ and HVAC system focused company. Since 1984 we have helped our customers realize successful outcomes with every imaginable duct cleaning scenario. PURE-Duct from our Building Remediation Sciences division is an IAQ driven service that takes duct cleaning to the next level. Occupant well-being and building performance are the top priorities. The PURE-Duct process is performed by highly trained NADCA and VSMR certified personnel. They follow the stringent guidelines outlined by those protocols for containment, equipment, and cleaning.

Our Building Sciences and Environmental Diagnostics Laboratory divisions will also provide support with testing in the case of more complex issues.
Article Source: https://pureaircontrols.com/3-signs-that-you-need-duct-cleaning/

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