HVAC preventive maintenance, by equipment type

HVAC preventive maintenance fails when a building has one schedule called "HVAC" instead of a schedule per equipment type. A rooftop unit, a chiller, a cooling tower and a fan coil in a guest room have almost nothing in common except the letters, and they fail in completely different ways.

Rooftop units

The two things that actually cause callouts are blocked filters and blocked condensate drains. Everything else is secondary.

• •Filters: check monthly in a dusty location, quarterly otherwise, and record the pressure difference across them rather than a visual opinion
• •Condensate drain and pan: clear and flush before every cooling season, and photograph the pan
• •Belts and pulleys where fitted: tension and alignment, with a deflection measurement
• •Coils: clean annually before the season that uses them
• •Economiser dampers: exercise them, because a stuck damper costs a fortune in energy and nobody notices

Chillers

Expensive to fix and slow to fail, which makes them the best candidate in most buildings for readings rather than visual checks. Log approach temperatures, pressures and running amps every visit and keep the last twelve.

• •Approach temperature on condenser and evaporator, recorded as a number every time
• •Refrigerant charge and any leak checks required where you operate
• •Tube cleaning on the interval the water treatment programme says, not a fixed calendar
• •Oil analysis annually on larger machines
• •Starter and contactor inspection, thermally imaged where you can

Cooling towers

The only piece of building plant where a maintenance failure is a public health matter. Water treatment and the legionella control scheme drive the schedule, and the schedule is not negotiable.

• •Water treatment checks at the frequency your written control scheme states
• •Drift eliminators, fill and basin inspected and cleaned on schedule, with photographs
• •Fan, gearbox and drive checks, with vibration where the tower is large
• •Full clean and disinfection at the interval in the scheme, recorded with dates and names

Fan coils, split units and heat pumps

Individually cheap, collectively the largest count in a hotel, a hospital or a residential block, and almost impossible to schedule because the rooms are occupied.

The pattern that works is a rotation rather than a date: a fixed number of rooms every week, tracked so that every unit gets done once a year, with the schedule following access rather than fighting it.

The two records that matter at audit

Filter changes with dates, and the water treatment log with results. Those are the two an insurer, an environmental health officer or an incoming owner will ask for, and they are the two most often reconstructed afterwards from memory.