A Pre-Winter HVAC Checklist for Maine Commercial Buildings

In Maine, the heating season isn’t a mild inconvenience — it’s six months of continuous demand on your equipment, with outdoor temperatures that can sit below zero for days at a time. A boiler or rooftop unit that fails in January doesn’t just mean an uncomfortable building. It can mean frozen pipes, sprinkler damage, closed businesses, and emergency service rates.

The good news is that most mid-winter failures give warning signs months earlier. A disciplined pre-winter inspection catches them while there’s still time to fix things on your schedule instead of the weather’s. Here’s the checklist we recommend for commercial buildings.

Boilers and hydronic systems

• Combustion analysis. Test flue gas for oxygen, carbon monoxide, and stack temperature. Poor combustion wastes fuel and can signal heat exchanger or burner problems.
• Burner and ignition. Clean and inspect burners, igniters, and flame sensors. Weak ignition is one of the most common causes of cold-weather lockouts.
• Safety controls. Verify that low-water cutoffs, high-limit controls, and pressure relief valves operate correctly.
• Venting. Inspect flues and chimneys for blockage, corrosion, or separated joints.
• Pumps and circulation. Check pump operation, listen for bearing noise, and confirm system pressure and air elimination.
• Water treatment. Test system water chemistry. Untreated water shortens the life of boilers and piping.

Furnaces, unit heaters, and rooftop units

• Heat exchangers. Inspect for cracks or corrosion — a safety issue as much as a performance one.
• Gas pressure and valves. Confirm correct inlet and manifold pressure and verify gas valve operation.
• Filters and belts. Replace filters and inspect belts and pulleys. A loose belt in December is an avoidable service call.
• Economizers and dampers. Make sure outside air dampers close properly. A stuck-open damper can freeze coils and spike heating costs.
• Freeze protection. Test freezestats and low-limit controls on any equipment with water or glycol coils.

Controls and building automation

• Verify thermostat and sensor calibration.
• Review heating schedules and setback temperatures for the season, especially in buildings with changed occupancy.
• Confirm alarms are working and routed to someone who will actually respond after hours.

The building envelope and vulnerable areas

Equipment isn’t the only thing that fails in winter. Walk the building and identify the places where a heating problem becomes a water problem:

• Pipes in exterior walls, unheated stairwells, loading docks, and mechanical rooms.
• Sprinkler risers and dry systems that need draining or testing.
• Doors and overhead doors that are left open for long periods.

Plan for the worst day

Even well-maintained equipment can fail. Before winter, make sure you know:

1. Who you’ll call for emergency service, and whether they already know your equipment.
2. Where critical shut-offs are and who on site can reach them.
3. Whether you have, or can quickly get, temporary heat for critical spaces.

When to schedule

The best time for pre-winter work in Maine is late summer through early fall. By the first hard freeze, every contractor in the state is busy, parts get harder to source, and small repairs start competing with emergencies.

MacPherson Werks provides scheduled preventative maintenance programs for single buildings and multi-location portfolios across Maine, with a written report after every visit. If your heating plant hasn’t been inspected this year, contact us and we’ll get you on the schedule.