How to run an HVAC startup that holds up in a warranty claim
A startup sheet has two readers. The first is the commissioning agent or owner's rep who wants proof the unit was started correctly. The second is the manufacturer's warranty department, eighteen months later, when a compressor fails and they want to see your superheat, your voltage imbalance, and whether the crankcase heater was on before you started it. A sheet that says "unit running good" helps neither of them. This HVAC startup checklist template records the readings that matter and does the math in the cell, so the numbers are consistent from tech to tech.
What's in the workbook
- RTU Startup: packaged rooftop units with a two-circuit refrigeration table, air side, and two-stage gas heat / combustion.
- Split System Startup: condensing units, heat pumps, air handlers, and fan coils. Includes the nitrogen pressure test, evacuation and decay readings, and cooling-mode vs. heat-mode readings.
- Boiler Startup: water-side prep, venting, gas train, low- and high-fire combustion, ΔT, and safeties (flame failure, LWCO, high limit).
- Chiller Startup: flow proving, freeze protection, two refrigerant circuits, evaporator approach, chilled and condenser water ΔT.
- Functional Performance Test: commissioning steps with expected vs. actual response, Pass/Fail, deficiency #, summary, and a deficiency log.
Pre-start: the checks that prevent day-one failures
Most early compressor and motor failures come from a short list of things nobody checked before energizing:
- Crankcase heater time. Scroll and recip compressors need the heater on for the time in the IOM (often 24 hours) to drive refrigerant out of the oil. Starting cold can slug the compressor.
- Phase rotation. Three-phase scroll compressors run backward on reversed rotation. They get noisy, don't pump, and fail quickly. Check rotation with a meter before the first start.
- Condensate trap. A draw-through unit with an unprimed or missing trap pulls air up the drain and throws water into the unit and the ceiling.
- Shipping hardware. Compressor hold-downs, fan tie-downs, and blower shipping brackets left in place.
- Construction filters. Change them before startup readings, or your airflow and ΔT numbers are meaningless.
Each check is Yes / No / N/A. A No turns red. Fix it or explain it in the notes before you start the unit.
Electrical readings and the math behind them
| Reading | How the sheet calculates it |
|---|---|
| Voltage % of nameplate | Average of L1-L2, L2-L3, L1-L3 ÷ nameplate volts. Flags CHECK outside the ± tolerance you set from the IOM. |
| Voltage imbalance | Maximum deviation from the average ÷ the average. Small voltage imbalance causes a much larger current imbalance and motor heating, so compare it to the manufacturer's limit. |
| Amps % of nameplate | Average amps per component ÷ RLA (compressors) or FLA (motors). Over 100% flags OVER NAMEPLATE. 90–100% on a mild day shades amber, which usually points to airflow, charge, or voltage. |
Take voltage at the unit disconnect with the unit running. Readings at the panel miss the voltage drop on a long feeder. The voltage drop calculator helps when the numbers don't line up.
Refrigerant circuit: superheat, subcooling, and approach
Let the unit run at least 15 minutes with the access doors on before you read the refrigerant side. Enter pressures, the saturated temperatures from your gauges or PT chart, and the line temperatures from your clamp. The sheet calculates:
- Superheat = suction line temp − saturated suction temp
- Subcooling = saturated liquid (condensing) temp − liquid line temp
- Evaporator approach (chillers) = leaving chilled water temp − saturated suction temp
Enter the Min / Max from the unit's charging chart or label. TXV and EEV systems are usually charged by subcooling, fixed-orifice systems by superheat. The Result column reads OK, CHECK, or RECORD (no limits entered). Rows marked (calc) are formulas, so don't type over them.
Air side, gas heat, and combustion
On the air side, record supply airflow and external static against the scheduled values, then return and supply temperatures. The temp split (RA − SA) calculates for cooling and the temperature rise (SA − RA) for gas heat. Compare the rise to the range on the furnace section's nameplate: too high usually means low airflow, too low usually means overfiring or a gas pressure problem.
For gas heat and boilers, record inlet gas pressure static and with all burners firing, manifold pressure at each stage, and the analyzer readings: O2, CO2, air-free CO, flue temperature, and efficiency, at low and high fire. Enter the manufacturer's limits as Min / Max. Keep the analyzer printout with the sheet.
Controls and the functional performance test
Each startup tab ends with a controls checklist: occupied and unoccupied modes, staging, economizer, DCV, smoke shutdown, condensate overflow, and safeties. Detailed commissioning goes on the Functional Performance Test tab, which works like this:
- Confirm the prerequisites: startup signed, TAB complete, point-to-point done, sequence approved.
- Write each step as a condition imposed and the expected response, taken from the sequence of operations.
- Run the step with the CxA present and record the actual response, Pass/Fail, and a deficiency number.
- The summary counts passes and fails and reads OPEN until every fail is retested.
- The deficiency log tracks each item to the responsible party, target date, correction, and verification.
Code and manufacturer references
Refrigerant relief piping, machine-room ventilation and detection, and A2L refrigerant requirements are governed by the mechanical code your AHJ has adopted (IMC Chapter 11 or UMC), ASHRAE 15, and the equipment listing. Verify against the editions adopted in your jurisdiction. The template doesn't reproduce code tables or manufacturer charts. Enter the values from the IOM and the contract documents.
Go digital when startups stack up
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