HVAC Startup and Commissioning Tests Ontario Homeowners Should Witness on a New Install

Why Commissioning Matters

Rated efficiency, capacity, and service life of residential HVAC equipment all assume the unit is set up within the manufacturer's specifications. When static pressure is higher than the blower is rated for, airflow drops and the heat exchanger runs hotter. When refrigerant charge is off by half a pound, measured efficiency can fall 10 to 15 percent and compressor life is shortened.[3]

Industry studies cited repeatedly by HRAI and ENERGY STAR Canada have shown that roughly 30 percent of new residential installs run at reduced efficiency, reduced capacity, or both, because commissioning was skipped or only partly performed.[4]This is not a manufacturer-quality problem. It is an install-quality problem, and the fix is the homeowner knowing what to witness on delivery day.

The Core Commissioning Tests

A furnace changeout needs gas, temperature rise, static pressure, combustion, flue draft, and airflow readings. An AC or heat pump changeout needs refrigerant, airflow, static, and thermostat readings. A full system change needs all of them plus Manual J/S/D.

Gas manifold and inlet pressure (furnaces, boilers, tankless)

Every gas appliance has a nameplate specifying manifold pressure (usually 3.5 in. W.C. for natural gas, 10 in. for propane) and minimum inlet pressure (5 to 7 in. W.C. on natural gas). The technician connects a manometer at the gas valve test ports and records both readings with the appliance running. Manifold pressure out of spec is the most common cause of under-firing and CO production. CSA B149.1 requires these readings before the appliance is left in service.[2]

Temperature rise across the furnace

Every forced-air furnace nameplate shows a temperature-rise range, typically 35 to 65 F. The technician measures supply-air and return-air temperatures at steady state and subtracts. Above the range means airflow is too low (dirty filter, closed registers, undersized return, static too high). Below the range means airflow is too high. Inside the range is pass; outside the range is a commissioning failure that must be corrected, not noted-and-left.

External static pressure (supply and return)

Static pressure is the push-back the blower is fighting. A typical residential furnace blower is rated at 0.5 inches W.C. total external static. Many installed systems run at 0.8 to 1.2 inches because ducts were never upgraded with the furnace. High static causes reduced airflow, higher temperature rise, louder operation, and premature motor failure. The technician takes two readings with a manometer (supply side just after the coil, return side just before the blower) and records both.[5]

Airflow CFM at the blower

Airflow is what actually reaches the rooms. On a variable-speed blower, CFM at a given static can be read from the manufacturer's airflow table. On a PSC blower the technician uses a TrueFlow grid or a rise-based calculation (BTU/h input x efficiency / 1.08 x rise). Airflow should be within 10 percent of the rated CFM for the selected cooling capacity (400 CFM per ton as the rule of thumb). Under-airflow is the root cause of many short-cycling complaints.

Refrigerant charge: superheat and subcool (AC, heat pump)

Charge is verified differently by metering device: a fixed-orifice (piston) system is charged to target superheat; a thermostatic or electronic expansion valve system is charged to target subcool. The technician hooks gauges to the service ports and compares the measured value to the manufacturer's target. Factory charge is usually close, but long or short line sets and dirty coils shift it. Too high a superheat means undercharge; too low a subcool with flooded refrigerant means overcharge. Commissioning means adjusting until both land on target.

Combustion analysis (CO, CO2, O2, flue temperature)

A combustion analyzer is probed into the flue and records CO, CO2, O2, stack temperature, and excess air. Modern condensing furnaces should show CO under 100 ppm air-free, CO2 in the 9 to 10 percent range, and stack temperature within the manufacturer's stated range. The technician should also do a spot CO measurement at a supply register; any reading above 9 ppm there is a red flag for a cracked heat exchanger or flue leak.[2]

Flue draft

On a Category I atmospheric-vent appliance (rare on new installs, common on furnace replacements in older B-vent homes), the technician verifies flue draft with a draft gauge to confirm combustion gases are drawn up the chimney, not spilling into the mechanical room. Draft is measured with the furnace running, all exhaust fans on, and the house closed to simulate worst-case winter conditions. A sealed Category IV condensing appliance uses PVC venting and is checked with vent-length and terminal-clearance measurements against the installation manual.

Condensate drain slope and trap

High-efficiency furnaces and AC coils produce condensate that must drain by gravity. Code requires a consistent slope (typically a quarter-inch per foot). On startup the technician pours water into the drain pan and confirms it flows freely. A float safety switch on the secondary pan is standard on horizontal installs; the installer should trip it to confirm the furnace shuts off when the pan fills. Slope failures surface weeks later as basement water damage.

Thermostat calibration and staging

A new thermostat should be calibrated against a reference thermometer. On two-stage and modulating equipment it must call for the right stages at the right differentials. A heat pump with backup gas furnace needs an outdoor sensor or configured balance point so the backup fires at the right temperature, not every time the heat pump can't keep up briefly. Miswired thermostats are a common post-install complaint and almost always trace to skipped commissioning.

The Homeowner's Startup-Day Checklist

TSSA Licensing: Who Can Touch the Gas

In Ontario anyone who installs, starts up, services, or disconnects a gas appliance must hold a valid TSSA certificate. G3 covers basic appliances under supervision; G2 covers residential and small commercial up to 400,000 BTU/h input (essentially every residential furnace, boiler, water heater, fireplace, and range); G1 covers any gas appliance of any size. Startup of a standard residential install requires G2 at minimum.[1]The certificate is issued as a wallet card with photograph, number, and expiry. A legitimate technician shows it without being asked, and TSSA maintains a registry for verification.[6]

On the refrigeration side the person handling refrigerant should hold an Ozone Depletion Prevention (ODP) card. Recovery, charging, and leak testing without it is a regulatory issue even on factory-sealed equipment. The Ontario trade is Residential Air Conditioning Systems Mechanic (code 313D).[6]

Manual J, S, and D: The Design Paperwork

Commissioning readings describe what the installed system is doing. Manual J, S, and D describe what it was supposed to do. Without the design paperwork the readings cannot be interpreted as pass or fail beyond crude nameplate bounds.[5]

• Manual J is the room-by-room load calculation. Inputs include window U-values, wall and ceiling R-values, infiltration, orientation, and occupants. Output is a total BTU/h heating and cooling load (sensible and latent).
• Manual S is the equipment selection that matches a specific furnace, AC, or heat pump to the Manual J load. A furnace should be sized close to the heating load at the Ontario 99 percent design temperature (roughly -18 C for the GTA), not oversized by 30 percent because it is a round-number model.
• Manual D is the duct-design calculation, confirming each supply can deliver the required CFM and each return can pull it back. Manual D is what is missing when a new high-efficiency furnace is dropped into ducts sized 40 years ago.

For a furnace-only or AC-only swap without duct changes, a full Manual D recalc is not always practical, but Manual J and Manual S should always be available. For any full system change, especially one adding a heat pump or changing duct runs, the homeowner should see all three.

Failing Results in Plain Terms

The homeowner does not need to read the gauges. They need to recognize symptoms that follow a commissioning failure, so they can call the installer back within the workmanship warranty window rather than living with substandard performance for years.

The Two-Hour Install Red Flag

A furnace-only changeout runs four to six hours of installer time on site before startup. A furnace-plus-AC changeout runs six to eight. A cold-climate heat pump install runs a full day. Commissioning adds another 45 to 90 minutes. An install crew that arrives at 9 and leaves at 11 has not done any of the work described in this guide.

The “two hours and out the door” pattern is common on high-volume lease and rental installs where the installer is paid per unit and the sales channel has no interest in workmanship after the ink dries. Ontario banned unsolicited door-to-door HVAC sales in 2018, and any homeowner who signed at the door has a 10-day statutory cancellation right under the Consumer Protection Act.[8]The clock is not the only evidence; the startup report is.

What to Do If the Paperwork Is Missing

Request it in writing the same day. Email or text is fine, as long as there is a dated record. Ask for the TSSA certificate number, manifold pressure, temperature rise, static pressure, combustion readings, any refrigerant-charge numbers, the permit number, and the Manual J/S/D summary. A legitimate contractor sends it within a day or two.

If the contractor refuses or stalls, there are two regulatory avenues. For the gas work, TSSA accepts complaints at tssa.org and can investigate any install it considers non-compliant with CSA B149.1 or the Gaseous Fuels Regulations.[1]For quote, cancellation, and consumer-protection issues, the Ontario Ministry of Public and Business Service Delivery administers the Consumer Protection Act.[8]

Where This Fits in the Buying Process

Commissioning is the closing act of a good install. It assumes the upstream work was done right: a proper quote, a verified contractor, a sized system, and clean financing. See our how to read an HVAC quote Ontario 2026 guide, our HVAC contractor insurance check guide, and our HVAC financing red flags guide for the pieces that precede delivery day.

Frequently Asked Questions

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