by Ali Kriscenski

As winter temperatures drop, heating issues become a top priority. Even minor thermal comfort variances can be signs of urgent maintenance or repair issues. If your tenants and occupants are wondering, “Why is my furnace blowing cold air?” your facility’s HVAC system needs attention. This article looks at how to identify heating problems, troubleshoot quickly, and avoid any major cold-weather headaches brought on by HVAC issues. 

5Importance of HVAC Performance in Winter

In certain regions, winter months can be dangerous. When the outside temperature dips, indoor air quality and thermal comfort become top priorities for comfort and safety. Furnaces that are working to keep interiors warm against freezing outside temperatures are protecting occupants from the elements and also keeping the property safe. Freezing pipes, water leaks and carbon monoxide exposure are all concerns during colder weather. 

Why Furnaces Blow Cold

Even if you have kept up with annual or biannual maintenance and needed repairs, the start of winter may put your HVAC system to the test. When you’ve discovered that your furnace is blowing cold air there are a few common issues that could be the culprit. 

System Size

When a furnace is blowing cold air, it may be clearing cold air in the ductwork as heated air starts coming through. To rule out this cause, check the airflow temperature over several minutes. If the issue clears, it may be time to look at the system size and determine if heating zones are configured properly.

Settings or Controls

If cold air continues to blow, check controls and thermostat settings to see if they have been programmed according to the current season. Occupant access to thermostats can easily disrupt the intended thermal comfort goals. The best strategy is to have overall system settings controlled by a facility manager and address occupant thermal comfort issues with decentralized controls, such as variable air volume (VAV) boxes. This solution keeps temperature settings while allowing individual spaces to receive higher or lower volumes of heated air supply.

Pilot Light

An easily identifiable cause of cold air blowing is the pilot light on the furnace itself. The pilot light is a small flame that ignites larger burners. If this has gone out, for instance, because of a draft, the system doesn’t have the energy needed to heat air. It may be blowing cold air because there is no heat source.


Fuel Supply

It’s possible your system is simply out of fuel. Similar to the pilot light, it may still be blowing air but without the heat source needed to bring the medium up to requirements. 

Dirty Sensors or Filters

Sensors communicate to the system to maintain, raise, or lower the desired temperature. If your thermostat is calling for heat and your sensor is blocked from the airflow by dirt or debris, the system will send conditioned air based on the sensor’s reading. Dirty air filters will block airflow that may be conditioned to the desired temperature. Both situations create energy overuse and could create system defaults from overheated wiring or devices.

Ductwork Damages

If your facility has had any maintenance or repairs done, it’s possible that that ductwork could have been inadvertently damaged or dislodged. If so, the airflow could be escaping into unfinished areas or be constricted.

Next Steps After Troubleshooting

If your team was able to target the cause of cold air blowing from the furnace, the remedy was likely found by an in-house repair. However, after exhausting the list of common issues without finding an answer, it’s time to get an expert on board. Pilot lights, thermostat settings and fuel supply are all straightforward and easily fixable problems. If the issues recur, you will want to consider a few additional maintenance approaches such as programmable controls and fuel delivery schedules.

With ongoing HVAC issues, your best bet is to contact an HVAC professional who can inspect the overall system and provide recommendations for heating strategies, system upgrades, equipment replacement or needed repairs. While the consult may cause unexpected costs, the expertise provided will create long-term energy savings, reduce occupancy disruption and create a higher-quality tenant experience.

Therma’s HVAC professionals provide maintenance services and expertise for commercial and industrial facilities.

Contact our experts today >>

Ali Kriscenski was trained in high-performance building design at Boston Architectural College. She has worked with leading architecture and construction firms in NYC and New England and served on the executive team at the Forest Stewardship Council International. She was the managing editor at Inhabitat and has worked pro bono for the Green Building Institute, ISEAL Alliance and Habitat for Humanity.


Delos — 3 Reasons Why Thermal Comfort is Key in Schools

Facility Management News — Thermal Comfort and Building Management