Plans

Two visits a year for most buildings, one for most houses, and a written record after each. Here is exactly what is in them.

October

The heating visit

Burners and ignitionCleaned and tested, including the flame sensor that accounts for a large share of no-heat calls.
Heat exchangerInspected. Where there is any doubt we say so plainly and do not leave the appliance running.
Flue and combustion airCondition, support, termination, and whatever has built a nest in it since March.
Gas pressure and safetiesMeasured and tested in operation, with the figures written down.
Airflow across the exchangerThe commonest cause of a furnace tripping its limit, and the item most often skipped on a cheap tune-up.
Heat pump settingsBalance point, staging and defrost, so backup heat runs when it is needed and not before.

April

Condenser coilInspected and cleaned before the season loads it with seed and dust.
Indoor coil and drainCondition checked, drain cleared, trap and float switch tested rather than glanced at.
Refrigerant behaviourMeasured with gauges and temperatures. Where a system is low we look for the leak instead of topping it up and leaving.
Airflow and static pressureMeasured — and the number that decides what filter the system can carry.
ElectricalCapacitors, contactors, connections and running current, recorded so next year has something to compare with.
Controls and schedulesWhether the equipment is running during the hours the building is actually used.

Plainly

Not an insurance policyMaintenance makes failures less frequent and finds faults while they are still cheap. It does not mean nothing will break, and anybody promising that is selling something else.
Not a licence to skip the diagnosisA fault between visits still gets measured and priced properly. Being on a plan does not turn a repair into a guess.
Not priced herePlans are priced after a survey, per unit, in writing. A figure on this page would only be wrong for your building.
Not a tieThe written record is yours. If you go elsewhere you take it with you, and the next contractor starts from something real.