Uneven Temperatures in a Commercial Building

Likely causes

These categories help organize the diagnostic process; they are not a remote diagnosis.

• Airflow imbalance, duct leakage or restriction, terminal, damper, diffuser, or return problems
• Sensor location or calibration, schedule, setpoint, zoning, sequence, or override issues
• Load differences from sun, occupancy, equipment, envelope, doors, ventilation, or tenant changes

Safe facility observations

Facility staff may record alarm text, thermostat or BAS display status, affected areas, time of onset, visible water or ice from a safe location, and unusual sound or odor. Do not open energized panels, reset a repeatedly tripping breaker, bypass safeties, force controls, handle refrigerant, work on combustion equipment, or enter pressure systems.

• Map affected zones, time, weather, occupancy, doors, and recent construction or tenant changes
• Record sensor values, setpoints, commands, airflow shown, and overrides
• Note blocked grilles or obvious space-use changes without entering equipment

Professional diagnostic process

Diagnosis compares load and space use with sensors, airflow, static pressure, ducts, terminals, dampers, equipment capacity and stages, ventilation, envelope, schedules, and controls.

Equipment commonly involved

The fault can originate in the primary equipment or a connected system.

• RTUs and air handlers
• Ducts and diffusers
• VAV or zone systems
• Sensors, thermostats, and BAS

Risks of delay

Delay can drive unsafe overrides, simultaneous heating and cooling, portable equipment, energy waste, tenant complaints, humidity problems, and equipment wear.

Repair considerations

Correct verified sensors, controls, terminals, ducts, airflow, ventilation, envelope interfaces, or equipment faults and verify representative zones.

Replacement considerations

Replacement or rezoning should follow load, airflow, distribution, ventilation, controls, tenant-use, phasing, and commissioning analysis.

Related maintenance

Trend zones, sensors, setpoints, overrides, dampers, terminals, static pressure, filters, coils, fans, equipment stages, ventilation, and recurring complaints.

Safety notice

This guide is educational and is not a substitute for on-site diagnosis. Follow facility safety procedures and applicable code. If there is smoke, fire, suspected gas, exposed electrical damage, a significant refrigerant release, pressure hazard, or an immediate life-safety concern, evacuate or isolate the area as appropriate and contact emergency or qualified response personnel.