The first cold front of the year is our busiest heating day. Most of those calls could have been caught in October.

The checklist

Replace the filter. Switch the thermostat to Heat and raise it 3 degrees. Listen for the inducer, then the igniter, then the burners.

If you smell more than a light dusty burn-off, or the furnace starts and stops within a minute, book a tune-up before the cold arrives.