As the weather turns and winter approaches, your HVAC system transitions from cooling to heating your home. Proper maintenance is key for this transition to happen smoothly–whether you use a gas furnace, electric heat or a heat pump.
But let’s say you do happen to find yourself in a situation where your house is cold and you don’t know why. While this is a frustrating situation and you’re concerned about potentially incurring a costly repair bill, below are a few key things you can check before calling your HVAC contractor.
For any traditional whole home furnace, electric heat or heat pump to work properly, the following conditions must be met:
The thermostat must be calling for heat and configured properly
Thermostat Calling for Heat: Check the simplest thing first by double-checking if the thermostat is in heat mode and set to a temperature that is above the current room temperature. If not, set to heat mode, turn up the temperature by at least three degrees higher than room temperature and try again.
Thermostat Configured Properly: If you’ve verified your thermostat is in heat mode and set to a temperature that is at least three degrees higher than the current temperature, and your heat still isn’t coming on, the next thing to check is if the thermostat is configured properly. Many thermostats have settings that must be set up properly for your given system, or it will not work. Consult the user or installer manual for your thermostat and ensure the system settings match your home’s specific system configuration. For example, if your thermostat is set up to control a heat pump and electric backup heat but you haven’t configured the thermostat for auxiliary heat mode, then it may not work properly.
The system must have power
Another common reason furnaces may not turn on is they simply don’t have power. Check the switch by the furnace (often looks like a light switch) and ensure it is in the “on” position. Note that the up position on the switch may not necessarily mean “ON” (nor will down always mean “OFF”). You’ll want to verify by inspecting the words on the switch itself or trying both positions before making any conclusions.
If you have a heat pump you will also want to check if the breaker outside near the condensing unit is in the “ON” position as well. Use caution when accessing those breakers as they are high voltage, and if you’re not careful, you can be severely shocked resulting in potential injury or death.
The last place to check is your main circuit breaker panel. Ensure all breakers are reset properly and in the “ON” position.
Gas furnaces must have the gas source turned on
Another possible reason your furnace hasn’t come on is if the gas source has been turned off. If you check near the furnace there should be a valve on the gas line with the lever in line with the pipe (or flex pipe) leading to the furnace. If the lever is perpendicular to the line, the gas is turned off. Before turning it on, you may want to consult your gas company or contractor as to why it was turned off in the first place, as they should be left on all the time.
The system must have proper airflow
Another major reason your furnace may not work properly is if it’s not getting adequate airflow. This is most often caused by covered returns, closed registers, or dirty filters. Check each of these to ensure your vents are open and your filter is in good condition.
If you’ve checked all of these and the heat is still not working properly, it’s time to call in an accredited HVAC professional.