Commercial industries may feel the chill of winter more so than other sectors due to the number of buildings and amount of floor space that refineries, chemical plants, data centers and similar industries require. More space brings the need for greater HVAC efficiency to maintain temperature levels and keep production processes moving along.
While smaller companies that reside in less-harmful environments certainly have to deal with HVAC costs and the associated maintenance responsibilities, for many businesses in the commercial sector, HVAC performance is a keystone of everyday operations. And with freezing temperatures and blankets of snow covering many parts of the country, these companies could be harder hit by extreme weather conditions.
In the event a pipe, drain line or HVAC coil becomes frozen, the system will have to be shut down. With large HVAC systems responsible for regulating airflow in hundreds of thousands of square feet, the cold has a disproportionately higher chance of making a negative impact on these units. That's why it's necessary for companies to take steps to protect against the winter elements at all costs.
Because cold temperatures cause contraction, metals can bend, break and crack under pressure, creating holes and millions of dollars in damages.
Check setpoints
Newer commercial HVAC units are highly optimized pieces of equipment that when combined with automated controls have the ability to interact naturally with both interior and exterior factors. It's important that these controls are properly set at appropriate ranges to protect against wild variations in the function of the unit.
To make sure the cold doesn't do excessive harm to an HVAC system, monitor and recalibrate setpoints so that the unit's response will fluctuate in line with outside conditions. For instance, freeze stats will shut the system off if the air inside the unit is too cold. This prevents the HVAC coils from freezing. When this control is tripped, it's apparent that there's likely a problem somewhere in the system.
In many cases, too much outside air is being let in, and during winter, this cold air is passed over the coils, potentially causing the copper or aluminum metals to freeze, especially with water or refrigerants present inside the coils. When this occurs, the passage of liquids and gases through the coils is restricted and can cause the coil to break.
Keeping an eye on setpoints will help prevent these instances.
Control head pressure
When concerning buildings like data centers, cooling is necessary year round. Even though outside temperatures may be sub-zero, the constant drone of computers and miles of electrical wires causes a lot of heat transfer. Without proper ventilation, these systems will overheat and potentially cause fires. However, using chilled water coils during winter poses a problem for HVAC systems because pressure levels can drop due to low outdoor temperatures.
As such, coils will freeze if the low side pressure drops far enough, which is why it's critical that pressure controls are in place, such as low ambient control systems. The fans will react accordingly to outside conditions, thus keeping head pressure inside a manageable range.
By maintaining pressure levels, coils won't freeze, which is important to keeping the system as whole running.
Remove excess water
As is the case with all HVAC units, residual water is almost always present no matter how sustained efforts are to prevent it from occurring. With HVAC evaporator coils quickly removing liquids at a fast rate, the excess is discharged and either cycled back into the system or removed via the drain line. However, excess water finds it's way through cracks and pinhole leaks, and when cratering is present in the coils, water will remain pooled inside.
Further, drip pans are responsible for filtering out this water through the drain line, but moisture and condensation usually still remain to some degree. Some companies turn to forcing hot air through the system to remove additional water and to keep the coils from freezing. It could be pertinent to drain the entire system from time to time in preparation for harsher weather so water doesn't freeze.
One of the best ways to keep water from collecting is to use superhydrophobic coated coils. This compound deters water from gathering and protects against cratering as well.
Keeping an HVAC unit working during the winter is a matter of taking precautionary steps toward efficiency. One simple change in pressure or temperature can cause a total HVAC failure if left unchecked. Take the time to isolate potential problem areas before they turn into bigger issues.
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