What To Do When Your Heater Won’t Turn On

Is your heating system ready for the winter? After months of inactivity, you might switch on your heater to find out that it doesn’t work.

We look at some of the most common HVAC issues with the help of HVAC specialists and brothers Pat and Steve Nugent of Virginia-based John Nugent & Sons.

The most common cause of heater issues is maintenance – or the lack thereof. Pat and Steve encourage homeowners to learn a little about their HVAC system. This way you’ll know when you can fix the issue yourself and when it’s time to call in the pros.

What To Check If Your Heating System Does Not Switch On

When it comes to heating system malfunctions, Pat and Steve have five there’s a list of things you can check yourself before calling an HVAC technician. While they may not work, they are simple fixes that could save you money on maintenance and repairs.

1. Replace the Batteries in Your Thermostat

While old analog thermostats never needed them, the new digital models rely on batteries. The thermostat will not work if the batteries are completely dead. On the other hand, weak batteries can cause your HVAC system to act oddly. So it’s best to just replace the batteries.

Most thermostats use standard AA, AAA, or 9-volt batteries. However, some systems may have specialty coil or button batteries. Check the owner’s manual for instructions on changing the batteries and other troubleshooting tips before calling a pro.

2. Check the Settings on the Thermostat

Another common mistake is choosing the wrong settings. Pat adds, “A lot of times, people accidentally hit the wrong button on the thermostat—either they hit ‘Cool’ when they meant ‘Heat,’ or they’ve just turned on the fan, not the heater.”

This is especially common if you are tired, frustrated, or stressed out. Take time to review the owner’s manual and make sure it is set to heat. Then, adjust the temperature and give it a moment to switch on.

3. Check the Circuit Breaker and Emergency Shutoff

Electrical issues are another common reason your heater won’t switch on. You should have a dedicated circuit breaker in your electrical box. Check if the breaker is tripped and reset it if necessary.

Pat and Steve caution that a breaker that repeatedly trips is a sign of a serious issue. If your heater does start working after resetting the breaker, keep an eye on it for the next several days. If the breaker keeps tripping, call an HVAC company to investigate the issue.

Most systems also have an emergency shutoff switch, which looks like a regular light switch. Check that the shutoff switch is in the “on” position, then toggle it back and forth to reset your heating system.

4. Change the Air Filter

Changing the air filter is the easiest maintenance task to perform, but also the easiest to forget. Surprisingly, clogged filters can cause several different problems.

“Homeowners should always check their filter,” says Steve. “A dirty filter can be the cause of issues like poor airflow—even to the point where the unit overheats and shuts off.”

If your heater turns on but does not produce hot air or it turns on and off intermittently, the filter may be so dirty that it’s interfering with normal operation. Even after changing the filter, you should still call an HVAC technician to check the system for lasting damage.

5. Cycle the Power on Your HVAC System

Advanced thermostats can lock out users if the diagnostic system detects a problem with the main unit. When that happens, Pat recommends shutting off power to the unit and then turning it back on again. “If it restarts and keeps running, that doesn’t mean you shouldn’t have a qualified technician check it out, but at least it’s working temporarily,” he says. “If it immediately goes back into lock-out mode, contact a technician right away.”

Signs You Should Call For Professional HVAC Maintenance

Unfortunately, there are some HVAC issues that are best left to the professionals. Here are some of the most common issues that only an HVAC technician should address.

If you have any of these issues, Pat and Steve recommend calling a reputable HVAC company immediately. Not only are they trained to repair and maintain HVAC systems, but they will prevent permanent damage and keep your family safe in the process.

Gas furnace burners don’t light

Heaters with standing pilot lights that can be blown out by drafts are increasingly rare these days—they’re simply less efficient and safe than units with electronic ignitions.

However, electronic ignitions such as surface igniters or spark ignition systems can also have problems, usually as a result of age or lack of maintenance. If the burners on your gas furnace simply don’t light, the problem may be a dirty ignition.

A technician can solve the issue by cleaning or replacing the part.

Gas furnace burners light but go off quickly

Gas furnaces include flame sensors, safety devices that shut off the gas when no flame is detected. Once again, age or lack of maintenance can make a flame sensor malfunction, causing the burners to shut off right after lighting.

The problem can often be resolved by removing and cleaning the part.

Excessive frost or ice on a heat pump’s outdoor unit

A heat pump’s outdoor unit tends to collect frost in the winter, but the device has a defrost mode to prevent ice buildup. Excessive frost or solid ice indicates a malfunction.

According to Steve, “The unit goes into defrost mode about every 90 minutes or so. If it doesn’t and starts to freeze, it’ll cost a lot more to heat your house and ultimately damage the heat pump.”

A failure to defrost properly is likely not a problem you can tackle alone, so if your heat pump begins blowing cool air in the winter, check for ice on the outdoor unit and consult a professional.

Seasonal Maintenance and Safety

Pat and Steve stress that seasonal HVAC maintenance is the best way to ensure your heater works when you need it most. This includes changing the HVAC system, replacing the air filter, switching heat pump settings, bleeding excess air from a boiler, and more.

Pat adds, “When your technician is at your house, feel free to stand around and ask questions so you know a little more about your system. We encourage people to do that.”

On a final note, Pat and Steve urge every homeowner, especially those in homes with a fuel-burning appliance, to install a carbon monoxide detector. A faulty boiler, cracked heat exchanger, or plugged-up chimney all have the potential to send carbon monoxide into the house.

“Having at least two carbon monoxide detectors is a good idea,” advises Steve. “Manufacturers usually recommend putting one just outside the furnace room and one close to the bedroom, so it can wake you up.”

If the alarm goes off, Pat and Steve say that your immediate response should be to open the windows, get everyone out of the house, and call the fire department. “Every so often,” says Pat, “you’ll get a false positive. But you’d rather make a big deal out of it than put your family at risk.”

This spotlight article was crafted by John Nugent & Sons, an Air Conditioning & Heating Best Pick serving Northern Virginia.

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