RTU HVAC Maintenance in Vancouver: What to Check Before Winter

A rooftop unit (RTU) is a packaged commercial HVAC system that heats and cools a building through its ductwork. All of it sits in one weather-resistant cabinet on the roof. In Greater Vancouver, winter readiness starts with testing the heat cycle, not judging how well it cooled in July.

October rain and coastal exposure make airflow checks and drainage part of that inspection. Facility staff can record thermostat behaviour and tenant complaints. A qualified technician should inspect the equipment. Gas work and high-voltage wiring belong to licensed trades.

Why Late October Is the Right Time to Test an RTU for Heat

Test the heating before a cold night makes the fault a tenant complaint. In the Lower Mainland, heating starts up as the wet season arrives in October. Equipment in exposed locations such as Lions Bay also faces wind-driven rain and occasional freezing Arctic outflows.

Energy Manager Canada reported on August 6, 2019, that BC Hydro considers RTUs an overlooked energy-saving opportunity. Its program manager estimated that roughly 20% of BC commercial customers had at least one RTU. Equipment left unattended in harsh weather becomes less efficient and more prone to breakdowns.

Run a Full Heat Cycle Before the First Cold Night

Ask the technician to watch a full heating cycle, from ignition through shutdown. Cooling operation does not test the gas heating section. Facility staff can call for heat at the thermostat and record the building's response without opening equipment panels.

1. Call for heat at the thermostat and record when warm air reaches the occupied space.
2. Note repeated starts and stops before the thermostat is satisfied. This is short cycling.
3. Report unusual odours. If there is a gas smell, leave the affected area and follow the gas utility's emergency procedure rather than continuing the test.
4. If operation appears normal, let the heating call finish and record its duration.
5. Give the technician the log of when tenants reported cold spaces.

Check Filters, Belts and Dampers Before Suspecting the Burner

Check airflow first. A clogged filter or slipping blower belt can reduce airflow enough to overheat the heating section. The limit switch then shuts the heat down to protect the equipment, making an airflow problem look like a burner fault.

1. Inspect the filter and replace it if loaded, using the specified size and type.
2. With power isolated, inspect the blower belt for wear and check its tension.
3. Have the technician confirm that dampers move through their intended range without binding.
4. Have static pressure checked against the unit's specifications to identify airflow restrictions.

A squealing belt on the first heating call deserves inspection. Repeatedly resetting a unit does not correct the restriction that caused it to trip.

Inspect the Gas Train, Flame Sensor and Heat Exchanger Under Lock-Out

Gas components and ignition controls belong on the licensed technician's inspection list. Lock-out/tag-out is required for work that needs the equipment isolated; operating tests require the technician's controlled testing procedures. Facility staff should not open the burner compartment.

A flame sensor confirms that the burner is lit. Contamination can prevent it from detecting the flame, causing the burner to light briefly and then shut down. Ask for the sensor to be checked during the pre-winter visit rather than waiting for repeated lockouts.

The heat exchanger separates combustion gases from the air delivered to the building. In a typical gas-fired heat section, combustion gases pass through the exchanger and exhaust outdoors while building air flows over its exterior. Have its condition assessed, and do not operate equipment with visible damage until a technician has inspected it.

Compare Measured Temperature Rise With the Nameplate Range

Have the technician measure the difference between return-air and supply-air temperatures across the heating section. Compare that temperature rise with the approved range on the unit's nameplate, not a general figure from a website. A reading outside the range calls for an airflow and burner assessment before parts are replaced.

Set the Economizer for Winter Instead of Summer

An economizer uses cool outdoor air to reduce mechanical cooling. That can help on mild days when an occupied commercial building still needs cooling. A damper stuck closed loses that benefit; one stuck too far open in cold weather increases the heating load.

Winter checks should confirm that the economizer responds correctly without cutting off the outdoor air required for ventilation. Simply closing the damper is not a winter setting.

1. Check actuator travel and confirm the damper responds to its controls.
2. Inspect the linkage for binding or disconnection.
3. Check seals for gaps that allow uncontrolled outdoor air into the unit.
4. Confirm the minimum outdoor air setting meets the building's ventilation requirements in cold weather.

Check Motor Amps and Electrical Connections Through the Licensed Trade

Have the technician compare blower motor current with the nameplate rating and inspect electrical connections for corrosion or overheating. Salt-laden coastal air accelerates corrosion, making this particularly relevant to near-shore buildings in Greater Vancouver.

Facility staff should keep high-voltage panels closed. Record when a noise or shutdown occurs, including whether it happens only at startup or continues throughout the heating call.

Clear Roof Drains and Condensate Lines Before the Heaviest Rain

Blocked roof drains can leave standing water around the RTU curb during the Lower Mainland's wet season. A blocked condensate path can also back water into equipment. Freezing conditions add another risk, so drainage belongs in the pre-winter inspection even if cooling has finished for the year.

1. Have the condensate drain and any fitted trap checked and cleared.
2. Arrange safe removal of debris around the curb and roof drains.
3. Inspect cabinet seams and exposed metal for corrosion, including coil fins.
4. Ask the technician to assess corrosion and have damaged curb seals reviewed before water enters the building.

Plan Four Inspections a Year, Kept Separate From Repairs

BC Hydro recommends preventive maintenance by a qualified commercial HVAC specialist four times per year, according to Energy Manager Canada's August 6, 2019 report. Budget scheduled visits separately from repairs. Bring the previous year's service records and tenant comfort complaints so the technician can look for recurring faults.

The same 2019 report described a variable-frequency drive upgrade for a two-speed fan at about $4,000, with approximately $2,000 in annual electricity savings and a two-year payback. These are dated examples, not current pricing or promised savings. Ask for an estimate based on your unit's operating hours and controls.

The schedule below is a planning example. Adjust the visits to your building's operating demands, with heating tested before cold weather and cooling checked before summer.

Visit	Timing	What to bring or ask for
Pre-winter inspection	October	Service records, tenant complaints and a complete heat-cycle test
Mid-winter check	January	Records of short cycling or heating shutdowns
Spring check	April	Cooling preparation and economizer operation
Summer check	July	Cooling performance and condensate drainage

A maintained commercial RTU commonly lasts roughly 15 to 20 years, but age alone does not decide replacement. Service history and equipment condition help determine whether another repair is a sound investment.

For a pre-winter assessment, review CCS's commercial rooftop unit installation and service, then contact Combined Comfort Systems with your unit details and service records. If the assessment leads to a replacement or retrofit, review our commercial financing page.

Frequently asked questions

What is the difference between an RTU and an AHU?

An RTU combines air handling with heating and cooling equipment in a rooftop cabinet connected to ductwork. An air handling unit (AHU) moves and conditions air but typically relies on a separate source of heating or cooling. An AHU can be installed indoors or outdoors, so location alone does not distinguish the two.

What usually causes a rooftop unit to lock out on heat in winter?

Airflow restrictions are a common starting point: a clogged filter or slipping belt can cause overheating and a limit-switch shutdown. A contaminated flame sensor can also cause the burner to light briefly and stop. Have a qualified technician diagnose the cause rather than repeatedly resetting the unit.

Can commercial rooftop HVAC units provide high-efficiency heating as well as cooling?

Yes, but efficiency depends on the model and heating system, not simply on its being an RTU. Packaged units can use gas heat, electric resistance heat or heat-pump heating. Compare the equipment's rated performance and suitability for the building, then check airflow and controls to ensure it operates as intended.

How often should a commercial RTU be serviced?

BC Hydro recommends four preventive maintenance visits per year by a qualified commercial HVAC specialist, according to Energy Manager Canada's August 6, 2019 report. In Greater Vancouver, schedule a heating test before winter and keep roof drainage checks in the wet-season maintenance plan. The exact work at each visit depends on the equipment and operating conditions.

Does regular maintenance extend an RTU's compressor life?

Regular maintenance helps protect the compressor by keeping airflow and controls working correctly. It cannot guarantee a particular compressor lifespan, and the whole unit's typical 15-to-20-year service life is not a compressor-specific estimate. Use inspection findings and repair history to assess its condition.