October 20, 2021
Common Reasons Why Your Heater May Not Shut Off
Your HVAC air filter is a small and relatively low-cost component that’s incredibly significant when it comes to overall furnace operation. If it isn’t changed out regularly, major problems can ensue. When the air filter is allowed to become excessively dirty, normal airflow decreases. The furnace has a much harder time drawing air in and distributing it. More importantly, it cannot efficiently cool down the interior of the building. This leads to longer operating times, lower indoor air quality, and accelerated system wear. If your heater is constantly running but your home never actually gets warm, one of the first things you should check is your HVAC air filter.
2. The Thermostat Is Set Incorrectly
Another simple and easy-to-resolve problem that might cause your furnace to run nonstop is an incorrect thermostat setting. When there are multiple residents in the household, there’s always the likelihood that someone else has cranked the thermostat to its highest possible setting. Check the temperature reading and the thermostat setting to see if this is the case. It’s also important to verify that your thermostat is in the right operating mode. Modern thermostats for central HVAC systems can be toggled between “HEAT” and “COOL.” Just next to these buttons is a switch that controls the fan. This should be set to “AUTO” rather than “ON.” When the fan is set to “AUTO,” the fan will automatically stop blowing air as soon as the desired indoor temperature is achieved. Conversely, whenever it’s set to the “ON” position, the fan will blow all of the time, even after the furnace has warmed the entire home.
If you’ve got an older thermostat, it may have a mechanical issue. As these units near the end of their life spans, the wiring that transmits their signals can become excessively worn and may short out. If the thermostat is damaged or malfunctioning, you can have a licensed HVAC technician replace it for you. This is an excellent opportunity to upgrade to a more modern and efficient thermostat for easy and ongoing energy savings.
3.The HVAC Ductwork Has Leaks
Leaky air ducts allow heated air to escape into remote areas of the property. For instance, there may be walls throughout the home that are hot to the touch. This means that the warm air being produced by your furnace isn’t reaching individual air vents for distribution. Instead, it’s seeping out of a leaky duct and being deposited behind the drywall. When this happens, the temperature of the indoor air never changes significantly, and the thermostat never turns the furnace off. Leaky ductwork can cause your energy bills to soar. It can also make it virtually impossible to maintain a warm, comfortable living environment. Scheduling a ductwork inspection will allow HVAC professionals to identify the exact areas of air loss and seal up any gaps, cracks, or holes.
4. The Blower Fan Motor Is Damaged
After you’ve checked your thermostat and your HVAC air filter, it’s safe to assume that your problem requires professional help. Among the most common causes for a heater that won’t shut off is a broken blower fan motor. The blower fan in your furnace draws air in and then distributes it after it’s been heated. Blower fan motors have fan limit switches that tell them to turn off when sufficient heat has been produced and then release. When a fan limit switch in a blower motor fails, the heater will run all of the time.
Even taking the casing off a blower fan motor to inspect the problem on your own can void your HVAC warranty. In the interests of keeping your manufacturer warranty intact, issues with this component should always be handled by a licensed HVAC company. If the fan limit switch is the culprit, it may be possible to resolve the problem by replacing or repairing the wiring to this switch. In other instances, the fan limit switch or even the blower motor itself might need to be replaced.
5. Your Heater Is Far Too Small for Your Home
There’s also a possibility that your heating equipment isn’t the right size for your home. This may be the case if you’ve recently had a new furnace installed and your new heater consistently underperforms. Undersized heaters don’t have the capacity to keep up with falling outdoor temperatures. During the winter months, these units will work harder and longer than they should. There are many calculations that HVAC installers must make before choosing residential heaters. The right heater will be the perfect size for both the building interior and the current ductwork.
An undersized heater can also be the result of recent building modifications. For instance, if you’ve just added on to your property but you have not made HVAC upgrades to account for your new space, heated air may be escaping to the remote room. As a result, the thermostat isn’t registering any significant temperature change.
At Scott-Lee Heating Company, we’ve been helping residents of St. Louis, MO, keep their homes warm since 1978. We offer heating and cooling system installation, maintenance, and repairs. We also provide indoor air quality services, metal work, and an expansive selection of top-quality HVAC products. If your furnace is running nonstop, we can find out why and resolve the problem. Call us today to request a quote or to schedule service.