Short-cycling is when a furnace, heat pump, or air conditioner turns on and off far more often than normal, running brief cycles that never fully heat or cool the home. Common causes are an oversized system, a dirty flame sensor, a tripping limit switch, restricted airflow, a plugged condensate drain, or a poorly placed thermostat.
Why it matters to you
Cycle count, not run hours, is what wears out a furnace: every start stresses the heat exchanger and igniter. Systems sized by square footage instead of a heat-loss calculation are a common source of short-cycling in Lower Mainland homes.
Practical guidance
Time a few cycles: on a cold day, heating runs of only a couple of minutes are a warning sign. Change the filter first, then book a diagnosis so the root cause is fixed rather than the symptom.