Every fall, a lot of commercial buildings get their heating “checked” the same way: someone switches the thermostat to heat, waits for warm air, and calls it done. The burner lit. The fans moved. The box is ticked.
That test tells you almost nothing. A heat section can light with a cracked heat exchanger, a gas pressure well off nameplate, a flame sensor one cold morning away from lockout, and a make-up air unit that has quietly stopped bringing in air at all. “It fired” and “it’s ready for January” are different statements, and the gap between them is where most winter no-heat calls come from.
Here is what a real commercial heating startup covers — the work our technicians do on Northeast Ohio buildings every September and October, and the questions worth asking whoever does yours.
Why heating equipment fails at startup, not mid-winter
Heating equipment in this region sits idle from roughly May to October. In those months, nothing exercises it: flame sensors pick up oxide, igniters age, condensate traps dry out, dampers and valves stick in whatever position they were left, and a mouse or a bird finds the flue. None of that shows up until the system is asked to run, and the first real call for heat usually comes on a cold morning with a full building.
That is why the startup visit matters more than any other heating service of the year. It is the one chance to find startup faults deliberately, with a technician standing at the unit, instead of discovering them at 6 a.m. on the first frosty Monday. (We made the same argument from the cooling side in our late-summer post on the heating handoff; this is the detailed version.)
Gas-fired rooftop units and unit heaters
Most commercial buildings in Northeast Ohio heat at least partly with gas-fired rooftop units or suspended unit heaters. A proper startup on each one goes well beyond watching it light:
- Combustion analysis. A calibrated analyzer in the flue reads oxygen, carbon monoxide, and flue-gas temperature, and calculates efficiency. This is the only way to know whether the burner is burning cleanly and safely — you cannot judge it by looking at the flame. High CO in the flue means something is wrong with the air-fuel mix, the burner, or the venting, and it gets fixed before the unit goes back in service.
- Heat exchanger inspection. The heat exchanger is the wall between combustion gases and the air your occupants breathe. Years of heating and cooling cycles can crack it. A visual inspection, and where warranted a camera, looks for cracks, rust-through, and separated seams. A compromised heat exchanger is a carbon monoxide risk, and carbon monoxide is colorless and odorless — nobody in the building will notice it on their own.
- Gas pressure. Inlet and manifold pressure are measured against the manufacturer’s nameplate. Low manifold pressure underfires the unit and can cause condensation and corrosion in the heat exchanger; high pressure overfires it and shortens its life.
- Ignition and flame proving. Igniters are checked, flame sensors are cleaned, and the flame signal is measured — a weak signal is a lockout waiting to happen. The inducer motor and its pressure switch get the same attention.
- Safeties. High-limit and rollout switches are tested to confirm they actually open. A safety that has failed closed doesn’t show up in normal operation — you only find out when it was needed.
- Venting. Flues and vent caps are checked for blockage, corrosion, and secure joints. A blocked vent is one of the most common causes of combustion gases entering a building.
Make-up air units: the heater nobody thinks about
Kitchens, manufacturing floors, and any building with significant exhaust rely on make-up air units to replace the air the exhaust removes. In winter, those units heat 100% outdoor air, so they carry some of the heaviest heating loads in the building — and they are often the least maintained equipment on the roof.
When a make-up air unit fails or its heat locks out, the building goes negative. Doors become hard to open, cold air pours in at every gap, and in the worst cases, gas water heaters and other naturally vented appliances can backdraft. A startup on a make-up air unit checks the burner and its safeties like any other gas heater, plus the outdoor air dampers, the discharge temperature control, and the interlock with the exhaust fans it is supposed to follow.
Boilers and hydronic systems
Boiler plants serve many of the region’s schools, offices, healthcare facilities, and older commercial buildings, and they have their own startup list:
- Combustion and burner setup, analyzed the same way as any gas-fired appliance, along with flame safeguard testing and a check of low-water cutoffs and pressure relief valves.
- Condensate handling on condensing boilers. High-efficiency condensing boilers produce acidic condensate. The trap must be primed and clean, and the neutralizer serviced, or the condensate attacks drains and the boiler can shut down on a blocked drain.
- Water side. Expansion tank pre-charge, air elimination, pump operation, and water treatment. Air trapped in the loop and low system pressure are behind a lot of “some rooms are cold” complaints.
- Glycol strength on any loop that runs outdoors or through coils exposed to outside air. The concentration is tested and topped up so the loop is protected against the coldest weather the region actually sees, not an average winter.
- Freeze protection on air handlers. Freezestats and outdoor air damper controls are tested on every air handler with a hot water or steam coil. A damper stuck open on a sub-zero night can split a coil in minutes.
If you are weighing whether your building’s heating approach still makes sense, our comparison of boilers, rooftop units, and VRF heating is a good place to start.
Controls: make sure the building actually asks for heat
A heating plant in perfect condition does nothing if the controls never call for it. A startup includes verifying that schedules, setpoints, and changeover logic are correct for the heating season — occupied and unoccupied setbacks, morning warm-up, and outdoor air minimums — and that every sensor the sequence depends on reads correctly. In buildings with a building automation system, that also means clearing out the overrides that accumulated over the summer. Overrides are the most common reason a well-maintained building wastes energy in winter.
When to schedule it
September through mid-October is the window. The equipment isn’t needed yet, parts are available, and repairs found during the startup can be made on your schedule. Wait until the first cold week and you are competing with every other building whose heat didn’t come on — and the work becomes an emergency call instead of a planned one. (If you’re already there, here is how our emergency service works.)
The simplest way to make sure it happens every year is to put it in writing. A commercial HVAC maintenance program schedules the heating startup each fall and the cooling startup each spring, so neither depends on someone remembering.
Questions to ask about your heating startup
Whoever services your equipment, these answers tell you whether you got a startup or a glance:
Was a combustion analysis done on every gas-fired unit, and can I see the readings? Printed or logged numbers are the proof.
Were the heat exchangers inspected, and how? “Looked fine” isn’t an inspection method.
Were the safeties tested, or just observed? A switch that was never opened was never tested.
What did you find that should be fixed before January? A good technician always has an answer, even if the answer is that the system is in good shape.
Air Temp Mechanical has kept Northeast Ohio commercial, industrial, institutional, and healthcare buildings warm since 1978. If you’d like your heating started up properly this fall — rooftop units, make-up air, boilers, and controls — our service team can schedule it before the cold arrives. Get in touch.
