Dirt Streaking: Sources, Causes, Effects And Solution

All kinds of supply vents, including the supply ceiling diffusers of your HVAC unit, can suffer from dirt accumulations. Many HVAC maintainers and professionals have to face the problem of dirt affecting both inner and outside areas of a ducting system. Apart from diffusers, the registers and grilles are also affected by the dirt and debris issue.

The sources of dirt streaking
Dirt streaking can be caused by the turbulent air that comes out of the air supply vent. The air leaving the supply vent comes out with great velocity, as it gets squeezed through vent’s louvers. The dirt particles, that the air contains, also become entrained and are deposited on the surfaces through which the supply air blows.

Sources of dirt particles
This dirt that comes out of the supply ceiling diffusers comes from mainly 2 sources.  It can come from the room or zone itself. The room air contaminants include candles, carpeting, people and pets, among others. The second source of the dirt particles is the unsealed openings. The sub floor or the drywall can have these boot penetrations that can form the unsealed openings. Particles get pulled towards space and get absorbed into the airstream.

Apart from these dirt causative factors, other conditions can also amplify dirt streaking. High amounts of room moisture can cause stickiness in the dirt particles, and they can get settled and get accumulated easily. Even when there is no moisture, then also the dirt particles get attracted towards the surfaces of the buildings. There is also the Coanda effect.

Solving dirt streaking
If the ducts, coils and the HVAC equipment are clean, then air streaking gets reduced quite substantially. There is no duct leakage and issues related to filter bypass. Now dirt streaking can be only caused by the sunsealed boot penetrations or by the particles that are present in the room itself.

If the sources of dirt are external, then vent penetration will have the “anti-smudge” rings. If the sources of dirt are internal, then the boot penetration should be sealed so that there are no gaps.  The UI classified fire dampers are a used so that the dirt build-up caused fire can be effectively controlled. Dirt, filth and debris can have great negative effects and are even causes of the fire. Hence, issues relating to the area should be solved immediately.

Different Types of Grilles and Diffusers such as Perforated Ceiling Diffusers

There exists a subtle difference between grilles and diffusers such as perforated ceiling diffusers. Grilles are devices that have been manufactured so that they can supply air in a vertical position without suffering from any deflected air - which would lose its flow, power and velocity. Perforated ceiling diffusers, or swirl diffuser - virtually any type of diffuser has little vents all around it. These are also called blades and these blades have the function of distributing or diffusing the air throughout the indoor space. The air that comes through from ventilation diffusers is cut at an angle in order to let this happen. 

There are many different types of ventilation grilles and diffusers. Many of these are differentiated between in terms of materials used, function, and applicability to different situations. Some of the different types of materials that grilles and diffusers are made of are:
1. Aluminium
2. Steel
3. Stainless steel
4. Plastic

These can all be given various finishes, in any colour of choice if required. Other finishes can be of stainless steel or brushed aluminium, among a few others. Variable air volume system manufacturers also sometimes coat their products in similar finishes.

There are many types of grilles and diffusers in general that a client can choose from. The most commonly chosen among these include:

1. Egg Crate Grille : These are very simple grilles that are also very affordable. They are usually used when air needs to be extracted.
2. Bar Grille : Bars are included instead of blades in this type of grille.
3. Transfer Grille : Mostly used to provide ventilation but are also useful for preventing the spread of smoke and fire in such an event.
4. Louvre Bladed Diffuser : Very commonly seen in this region, these ceiling diffusers are capable of directing air in up to 4 directions.
5. Straight Bladed Diffuser : Similar to the previous diffusers, but are quite cheaper in comparison. They also sport adjustable blades.

Why do VAV box suppliers encourage owners to retrofit to DDC controls?

Variable air volume boxes as a part of HVAC systems in a building or facility have been in use for a long time. For more than thirty years variable air volume units have been providing comfort in the form of perfectly conditioned air to hundreds if not thousands of people at a time who are all located in the same open air space.

In today’s market you will find many different kinds of variable air volume boxes today. If you are on the lookout for HVAC items such as these, and others such as displacement units, all you have to do is look for the right VAV box suppliers. If you are able to find reliable and highly reputable VAV box suppliers then you will find that they stock variable air volume systems of all natures, that are suited to different purposes and load capacities. On the flip side, if you are working with a lot of variable air volume boxes then you will find a wider range of such systems, dating from years ago to brand new variable air volume system.

Some of these variable air volume boxes will be simple shutoff systems, while others will be more technologically advanced. The vast majority of them, however, will be in need of some sort of repair or replacement, especially in terms of the controls. If the controls on a variable air volume system are not reliable, then the entire system is not reliable. For this very reason many VAV box suppliers will recommend that, instead of constantly repairing and testing the system, building owners and contractors retrofit their existing VAV box with pressure independent DDC controls. This is particularly beneficial when dealing with older VAV boxes with electronic controls. Some of the many benefits of retrofitting with DDC are:
 

1. Improved Function: 

DDC controls enable users to see operational variables which allow for more accurate and controlled heating and cooling responses.

2. Improved Efficiency:

DDC controls also allow users to make more accurate adjustments in different modes.

3. Improved Overall Efficiency: 

Installing a whole system of DDC VAV boxes will provide feedback which can help optimize fan operation and reduce energy consumption.

VAV boxes have a lot to gain from being retrofitted with DDC controls, and the biggest bonus to this are the long term energy savings which amount to a significant sum.

What You Need to Know about a UL Classified Fire Damper

Not many people who are not implicitly familiar with the industry will know the details about fire dampers, in fact, the general consensus is that it is a helpful part of the framework of a building in the event of a fire emergency. Fire dampers play an essential role in helping to curb the spread of fire. A UL classified fire damper is used to maintain the fire ratings of other fire rated walls, floors, etc. when they are interrupted by ducts.

Fire dampers shut close in the event of a fire emergency to prevent the flame from spreading further, especially through ductwork and eventually the supply ceiling diffuser in Dubai. This is possible because of a fusible link installed in the ductwork, which is designed to melt at 73.8 degrees Celsius, thus causing the UL classified fire damper to close. There are certain situations where the fusible link is designed to withstand hotter environments and respond to a temperature of 100 degrees Celsius. This is because some environments create a hotter “normal” temperature that is not indicative of a fire. Being an Underwriters Laboratories or UL classified fire damper means that the damper has been certified to carry a fire resistance rating which is measured in hours. This rating usually goes from 1.5 to 3.0 hours.

There are two major types of fire dampers. These are Dynamic Fire Dampers, and Static Fire Dampers. Dynamic Fire Dampers are used in situations where the building’s HVAC system’s blower will keep working in the event of a fire, or the Fans On mode. Static Fire Dampers are meant to used in emergencies when the HVAC system’s blower will be in Fans Off mode. This distinction is important because Dynamic Fire Dampers are specially designed to be able to function correctly against a strong air flow.

This post outlining the purpose, function, and types of fire dampers reveals how important they are to the structural integrity of a building’s fire safety standards. Highly rated fire dampers are responsible for containing a fire to as small a size as possible, preventing quick spread and heavy losses in densely populated areas.