Level up your home.

Switch the furnace off at the thermostat. Slide the filter out and hold it up to a light. If you can’t see light through it, replace it with the same size (it’s printed on the frame), arrow pointing toward the furnace.

Press and hold each alarm’s test button until it sounds. Replace weak batteries, and replace any alarm past the date printed on the back. In Ontario, homes with a fuel-burning appliance need a CO alarm outside sleeping areas.

Walk each room and move furniture, rugs and curtains off the floor registers and return grilles, so warm air can actually get around the house.

High-efficiency furnaces vent through pipes on an outside wall. Keep snow, ice and leaves away from them, and from a heat pump’s outdoor unit, all winter long.

If your thermostat takes batteries, change them before the cold sets in, so it never goes blank on a January night.

Trim plants and clear leaves, grass clippings and stored stuff so there’s about 60 cm (2 ft) of open space around the outdoor unit.

The same filter works just as hard in cooling season. Hold it up to the light and replace it if it’s clogged.

On the first warm day, set the thermostat to cool, a few degrees below room temperature. Cool air within a few minutes? You’re set. If not, call before everyone else does.

If your furnace has a humidifier, turn it off and close its bypass damper for summer, so you’re not adding moisture while the AC takes it out.

Water purification cartridges have a replacement schedule. Find yours on the housing or in the manual, and note when it’s due.