Dipping temperatures and cold Michigan snowstorms make a home’s heating system vital. But the first time you wake up to a frosty morning inside the house, you know something’s gone wrong. If your home furnace isn’t working, here are some troubleshooting tips to discover why there is no heat.

A quick online search will tell you that the first two things to check might seem obvious but can be overlooked. No matter what type of furnace you have, it will help to first check if there is power to the unit, and the thermostat. After that, there are troubleshooting differences, depending on the type of heating system installed.

The furnace needs power

First, make sure there is power to the furnace; a breaker could have gone out. Some furnace models also have a separate power switch that looks like a light switch. This may be located on the furnace or on a nearby wall. If that’s been shut off, there is no power to the furnace.

Is the pilot flame out?

Older furnaces had an obvious pilot light. A pilot light can go out due to a strong draft, dirty orifice or dirt in the gas tube. Carefully relight the pilot light. The thermocouple may also be faulty and is shutting off the gas supply. If this is the case, the problem is a bit more involved and may require replacing the thermocouple.

Is the flame sensor dirty?

The flame sensor safeguards the furnace against the unsafe burning of fuel. If this is dirty, the furnace may not function right. First, make sure power to the furnace is disconnected at the breaker box. Consult your owner’s manual to locate the flame sensor. Follow the directions to remove the sensor, carefully clean and reinsert it.

Is the filter dirty?

People often forget to change the filter on a forced air furnaces. If the furnace filter is dirty, it may throw the limit switch so that it needs to be manually reset. And, if the filter is not allowing adequate airflow, this could also kick off the limit switch. Changing the filter once a month is recommended.

Did you just change the filter?

On a forced air unit, when you take the blower door off to change the filter, it automatically shuts off power to the furnace. Make sure the door is aligned and on properly after a filter change.

Thermostat Troubleshooting

Simple things can trigger unresponsiveness in a thermostat when heat is needed. Run through this quick checklist:

Is the thermostat set for heat?

Sometimes this switch can get bumped when dusting. Try moving the switch from Auto to Heat to see if there is a difference.

Is the dial set to a temperature that is calling for heat?

Carrying an oversized box or piece of furniture past the thermostat may bump the thermostat dial, changing the setting.

Is the thermostat dusty or dirty inside?

Accumulated dust can be a problem, so remove the cover and make sure there isn’t a dust buildup.

Have the batteries died?

Programmable thermostats need a good battery. Know which kind yours needs and keep spare batteries available. It’s recommended to change the batteries at least once each year.

Is the thermostat old?

It may be possible that the thermostat has gone bad and needs to be replaced, but troubleshoot some other areas here first to be sure.

After addressing these common problems, there are some helpful tips to understand about the different types of heating systems. When there’s no heat, look for other causes based on whether you have an oil-burning unit, an LP furnace, a hot water or steam boiler, or a forced air system.

Oil burning units

Do you have oil in the tank? Was the tank recently filled?

Filling a tank stirs up any sediment that remains inside, which could cause a blockage in the system. Due to temperature changes, there can often be condensation inside the tank. It’s a good idea after an oil fil to shut the furnace off for about an hour. This will allow the sediment or other solids to settle to the bottom of the tank.

Above-ground oil tanks are usually set slightly off-level, and the oil is drawn from the higher end of the tank. So, there may still be some oil inside, just not where it can be reached. For buried oil tanks, the fill level is above the bottom of the tank, so avoid the debris at the very bottom.

LP Gas units

Sometimes the level of natural gas is so low that there isn’t adequate gas pressure. Schedule another delivery as soon as possible.

If the propane is completely gone from the tank, the delivery company should perform a pressure leak test before they fill the tank.

Tanks that are outdoors and above ground typically require a chemical additive to prevent freezing in winter months. See if this is needed in your tank.

Hot Water or Steam Boiler

Was the power switch turned off?

If a boiler system quits, people often shut off the electric power to the unit, which also shuts off the circulation pump. This stops the water from circulating through the system, potentially allowing it to freeze somewhere in the lines. If the shutoff switch has moved to “safety mode”, that means the unit has sensed a problem and is operating under a safety protocol. The safety mode does not usually require that you shut off the entire unit.

Is there adequate water pressure?

Check to be sure the water level is correct, which should be at half-full. The boiler’s automatic filling system, controlled by the pressure-reducing valve, should maintain water at the proper psi of pressure.

Is the expansion tank operating properly?

The heated water in a boiler system expands. The expansion tank is designed to prevent pressure increases because of this water expansion. If the tank contains excess water, it cannot absorb the extra pressure that is being released.

How is the flame burning?

The boiler requires an open flame to heat up the water. If the flame sensor is dirty, it may be preventing the flame from staying lit, thus not heating the water or producing heat.

Be frugal to save energy or leave the zones open?

When it’s severely cold, keep all zones circulating somewhat. You don’t save much energy by completely shutting off a zone that isn’t in use, and you run the risk of frozen pipes within that zone.

Frozen pipes can also happen even if there is a leak of outside air due to a phone line or cable access point from the outside not adequately insulated. Dryer vents often allow access of this freezing air, which affects nearby pipes. Insulate and caulk the entry points of these lines to prevent outside airflow.

Call for furnace repair

Simple troubleshooting tips like those explained above might solve the problem of no heat in the winter. However, furnaces are complex systems with many parts. A furnace repair professional can quickly troubleshoot and resolve the problem when the furnace or boiler aren’t working.

A regular maintenance plan by a qualified HVAC technician also prevents furnace malfunction. Contact Naugle Plumbing and Heating to service your home heating system and keep things warm all winter.