Water-source heat pump annual maintenance checklist

Zone outage agreed with the owner and occupants told

Outage time agreed with the owner, occupants told how long the zone goes without heating or cooling, finishes under the access panel covered against water-side spills.

Every electrical feed to the unit locked and tagged

Disconnect and any separate heat or control feed locked out, zero voltage proven. For tests: panels on, people clear, locks off by whoever hung them, re-locked before hands go back in.

Coil deep-cleaned and drain pan pulled and re-pitched

Coil cleaned through the full fin depth, no leaks at the tube connections, pan removed and scrubbed to bare surface, pan and line re-pitched to drain and trap rebuilt and primed.

Blower and motor serviced

Motor bearings checked, wheel cleaned and balanced, amp draw within nameplate at each speed, no imbalance or rub.

Loop isolation valves closed and pressure bled at the unit

Supply and return isolation valves closed, pressure relieved at a test port or drain into a bucket, and a towel under the strainer cap before it opens.

Strainer cleaned and hose kit and isolation valves serviced

Y-strainer basket pulled, cleaned and reseated, hose kits and unions checked for wear and leaks, isolation and any motorized valve stroked full range and seating.

Valves reopened and the coax vented before the unit runs

Strainer cap sealed, isolation valves fully open, air vented from the water side and the connections checked dry before power is released for the flow test.

Flow and pressure drop verified across the coax

Pressure drop across the water-to-refrigerant coax measured and compared to the manufacturer's flow curve, autoflow or balancing valve confirmed delivering design flow, entering and leaving water temperatures logged.

Reversing valve operation proven under load in both modes

Unit driven through heating and cooling under real load, reversing valve shifting fully and holding, refrigerant operating pressures and temperatures read where the system allows and compared to the data plate, a low reading treated as a leak to find rather than a top-off.

Electrical connections and thermostat verified

Terminal and disconnect connections tight with no heat discoloration, contactor and capacitor sound, thermostat calibrated and occupied and unoccupied modes proven with no overrides left set.

Compressor current read against the nameplate in both modes

Under the site's energized-work procedure and its PPE, compressor amps read in heating and cooling and compared with the nameplate and last year's reading.

Pressure and freeze lockouts proven by the manufacturer's method

High and low pressure and water coil freeze protection each shown to stop the compressor by the manufacturer's test method, fault read and reset, nothing left bypassed.

Sealed circuit opened only by a certified refrigerant technician

Access fittings used, a leak repaired, or refrigerant recovered or weighed in only by a certified refrigerant technician, recorded by refrigerant type and weight.

Unit closed up, locks cleared and returned to the owner's schedule

Cabinet panels and ceiling tile back, locks removed by whoever hung them, unit running on a thermostat call with no lockout and the owner's schedule restored.

Annual water, amp and pressure-drop readings filed by unit tag

Entering and leaving water temperatures, coax pressure drop, compressor amps and strainer condition recorded against the unit tag as the baseline for next year.