Commercial heating systems play a vital role in maintaining comfort and productivity in office buildings, manufacturing facilities, retail spaces and other business environments. Heating failures can disrupt operations, make workers and customers uncomfortable, and potentially reduce productivity.

Heating problems can vary in severity and have a range of root causes. The issues that cause a furnace or commercial heating system to circulate lukewarm air may be different than the problems that cause it to blow cold air.

Commercial HVAC systems are inherently complex, and it typically requires in-depth diagnostics performed by experienced technicians to accurately pinpoint the cause of a heating failure and develop a long-term solution.

Thermostat Issues

One of the most straightforward reasons why a commercial heating system may blow cool air is a faulty thermostat. In commercial buildings, thermostats are often more advanced than those found in homes, and they may control multiple zones or interact with other building management systems (BMS). If the thermostat is not set correctly, or if it's malfunctioning, it could send the wrong signal to the heating system.

Common thermostat-related issues include:

• Incorrect settings, such as the thermostat being set to “cool” instead of “heat” mode.
• Programming errors, especially in systems that have complex schedules for different zones or times of day.
• Calibration issues, where the thermostat isn’t accurately measuring the room temperature.
• Thermostat malfunctions due to old age, wiring issues or connectivity problems in smart thermostats or BMS-integrated devices.

Verify that the thermostat is set to "heat" mode and that the desired temperature is higher than the current room temperature. If the thermostat appears to be malfunctioning, it may need to be recalibrated or replaced by a commercial HVAC technician.

Airflow Restrictions or Blockages

Another common issue in commercial heating systems is restricted airflow. These systems are often larger and more complex than residential units, so airflow problems can arise in multiple areas, from ductwork damage or blocked registers to dirty filters.

Possible airflow problems include:

• Clogged air filters, which are especially common in commercial environments where air pollutants and debris can build up quickly.
• Blocked or closed air registers or vents, which can prevent the warm air from circulating effectively.
• Damaged or obstructed ductwork.

Insufficient Fuel Supply

In commercial buildings that use gas or oil-fired heating systems, an insufficient fuel supply could be the reason the heating system is blowing cool air. Without enough fuel, the burners won’t be able to generate enough heat to warm the air, resulting in cool air being circulated instead.

Common causes of insufficient fuel supply include:

• Gas line issues, such as leaks, blockages or low pressure.
• Oil tank running low or out of fuel.
• Faulty gas valves that fail to open properly, preventing fuel from reaching the burners.

If supply isn’t an issue, an experienced commercial HVAC technician should be able to diagnose and resolve the problem.

Burner or Ignition Failure

For commercial heating systems that rely on burners or ignition systems to generate heat, a failure in these components can result in cool air being blown instead of warm air. This issue is particularly common in older systems, where wear and tear can cause the burners to malfunction or the ignition system to fail.

Causes of burner or ignition failure include:

• Dirty burners, which can cause incomplete combustion and reduce heat generation.
• A faulty ignition system, such as a broken pilot light or electronic ignition, that prevents the burners from igniting.
• Problems with the flame sensor, which detects the presence of a flame and shuts off the system if no flame is detected, even if the system is trying to produce heat.

Have a qualified HVAC technician inspect the burners and ignition system. Cleaning the burners or replacing faulty ignition components may resolve the issue.

Heat Exchanger Problems

In commercial heating systems, the heat exchanger is responsible for transferring heat from the combustion process to the air that circulates through the building. If the heat exchanger is cracked, damaged or malfunctioning, it may not be able to transfer heat effectively, causing the system to blow cool air.

A cracked heat exchanger is a serious issue, as it can also lead to dangerous carbon monoxide leaks in gas-fired systems.

If you suspect a problem with the heat exchanger, shut off the system immediately and contact a commercial HVAC professional. A cracked heat exchanger must be repaired or replaced ASAP as it could pose a threat to those in the building.

Refrigerant Leaks in Heat Pump Systems

Some commercial buildings may use heat pump systems to provide zoned heating and cooling. In heating mode, a heat pump extracts heat from the outside air and transfers it indoors. If the system is low on refrigerant due to a leak, it may not be able to extract enough heat, resulting in cool air being blown through the vents.

Signs of a refrigerant leak include:

• The system blowing cool air even when set to heating mode.
• Icing on the outdoor unit.
• Hissing or bubbling sounds coming from the HVAC system.

Refrigerant leaks must be handled by a licensed HVAC technician. They can repair the leak, recharge the refrigerant and restore the system’s heating capacity.

System Overload or Improper Sizing

In commercial settings, heating systems that are too small for the building’s heating load may struggle to provide adequate warmth. This can lead to the system running continuously without ever reaching the desired temperature, and in some cases, blowing cool air because it is overwhelmed.

If the system is improperly sized, it may be necessary to upgrade to a larger unit that can meet the building’s heating needs. An HVAC professional can perform load calculations to determine the correct system size for your facility.

Address Commercial Heating Issues for Your Arlington, TX Business

If your commercial heating system is blowing cool air, contact a licensed HVAC technician at Tom’s Commercial here on our website or give us a call at 817-857-7400. We will quickly dispatch technicians to inspect the system and recommend the appropriate solutions.