Temperature complaints are the most common HVAC call in offices and retail spaces. One side of the floor is freezing, the corner office is stuffy, the front of the store is cold every time the door opens. Turning the thermostat up or down rarely fixes it, because the cause is usually somewhere else in the system.
Start with the pattern
The most useful thing you can do before calling is notice when and where it happens. A whole space that is too hot or too cold points toward the equipment or its controls. One room or one side of the building points toward zoning, airflow or the building itself. A problem that only happens at certain times points toward schedules, sun load or occupancy.
1. The rooftop unit is not keeping up
If the whole space drifts away from setpoint, the unit may not be delivering full capacity. Dirty coils, low refrigerant, a weak burner, a slipping belt or a compressor problem can all leave a unit running constantly without reaching temperature. Short cycling causes similar complaints; see our guide to rooftop unit short cycling.
2. Thermostat location and settings
A thermostat on a sunny wall, beside a printer, near an exterior door or above a supply diffuser reads the wrong temperature and controls the whole zone from it. Schedules that do not match actual hours, setback temperatures that recover too late in the morning, and tenants adjusting shared thermostats are all common causes.
3. Zoning that no longer matches the space
Offices get renovated. Walls go up, meeting rooms are added and open areas are split, but the HVAC zones often stay as they were. A room with no supply air, or one controlled by a thermostat in a different space, will always be uncomfortable no matter how well the equipment runs.
4. Airflow and ductwork
Closed or blocked diffusers, disconnected or crushed ducts, stuck dampers and VAV boxes that are not responding all change where the air goes. A space that feels stuffy rather than just warm often has an airflow or ventilation problem.
5. Outdoor air and the economizer
Rooftop units bring in outdoor air for ventilation. If an economizer damper is stuck open in winter, the unit can be fighting a large load of cold air. Stuck closed in spring and fall, the building can overheat on mild sunny days when free cooling should be helping.
6. The building itself
Large west-facing windows, entrances without a vestibule, loading doors and high ceilings create loads that the original design may not have accounted for. These problems can often be improved with air balancing, controls changes or targeted equipment.
What to note before you call
- Which rooms or areas are affected, and which are fine.
- Time of day and weather when it is worst.
- What the thermostat reads compared with how the space feels.
- Any recent renovations, layout changes or new equipment.
- Whether it is a new problem or has been going on for a while.
Getting it fixed properly
Comfort problems are rarely solved by one part. A good visit checks the equipment, the controls and the air distribution together, then explains what is causing the complaint and what it will take to fix it. Ongoing commercial HVAC maintenance keeps the equipment side from becoming part of the problem.
YYC Mechanical provides commercial HVAC service and rooftop unit repair for offices, retail and commercial buildings across Calgary. Managing more than one building? See our support for property managers.