No heat? 8 things to check before you call

Before calling for service, check the thermostat mode and batteries, the furnace power switch and breaker, the air filter, the furnace door, the condensate drain, the outside vent pipes, your registers and the gas supply to other appliances. These eight checks fix a surprising number of no-heat calls. If you smell gas or your carbon monoxide alarm sounds, skip the checklist and leave the house.

Safety first

If you smell gas (a rotten-egg odor) or a carbon monoxide alarm goes off, do not touch switches or the thermostat. Get everyone out, then call 911 or Nicor Gas at 888-642-6748 from outside. Nicor Gas runs that line 24 hours a day. Also, never open the burner compartment or bypass a safety switch. The checks below are all safe for homeowners.

The 8-point checklist

1. Thermostat mode. Set it to HEAT and raise the temperature 3 to 5 degrees above the room. Check that a schedule or vacation hold isn't overriding you.
2. Thermostat batteries. A blank or dim screen often means dead batteries. Many thermostats need them even when they are wired.
3. Furnace power switch. Look for a light switch on or near the furnace (sometimes at the top of the basement stairs). It gets turned off by accident more often than you'd think.
4. Circuit breaker. Find the breaker labeled furnace in your panel. If it is tripped, reset it once. If it trips again, leave it off and call.
5. Furnace door. The blower door has a safety switch. If the panel isn't seated firmly, the furnace won't run. Press it into place; don't remove inner panels.
6. Air filter. A badly clogged filter can make the furnace overheat and shut down. Replace it if it's dirty.
7. Condensate drain and pump. High-efficiency furnaces (white plastic vent pipes) make water. If the drain hose or pump is full or clogged, a float switch stops the heat. Look for standing water and call if you find it.
8. Outside vent pipes and registers. After snow, clear drifts away from the intake and exhaust pipes outside. Inside, make sure supply registers and return grilles are open and not blocked.

One more clue: other gas appliances

If your gas stove or water heater also isn't working, the problem may be the gas supply to the house rather than the furnace. Don't try to relight anything yourself; call Nicor Gas from outside if you suspect a gas problem.

Keeping the house safe while you wait

• Close curtains and blinds at night and open them on sunny south-facing windows during the day.
• If you use a space heater, choose one with tip-over and overheat shut-off, keep it 3 feet from anything that can burn, and plug it straight into a wall outlet.
• Never use a gas oven, grill or generator indoors for heat.
• In a hard freeze, open cabinet doors under sinks on outside walls to help keep pipes from freezing.

What to tell the technician

A few details help us fix it faster:

• When the heat stopped and whether it happened suddenly or slowly
• Any blinking light pattern on the furnace control board (count the blinks)
• Whether the blower runs, the burners light, or nothing happens at all
• Any unusual sounds or smells before it stopped
• Which of the eight checks above you already tried
• The furnace brand and model number from the label inside the door frame, if you can see it without removing inner panels

When to call a pro

Call if the checklist doesn't bring the heat back, the breaker trips again, you see a blinking error code, there's water around the furnace, or the furnace tries to start and shuts off. Yogi Heating & Cooling serves Schaumburg and nearby suburbs. Call (814) 431-1709, or use our emergency service page if it's very cold and you have kids, older adults or pets at home.

Related

• Emergency service
• Furnace and heating repair
• Why is my furnace blowing cold air?
• What to do when your carbon monoxide alarm goes off

Sources

1. Nicor Gas - Contact Us (24-hour leak and emergency line)