On your thermostat, look for the fan settings. There should be two, “ON” and “AUTO.” If it seems like your furnace won't turn off, the thermostat may be set to “ON” for the blower. Toggle the switch to “AUTO” so your furnace's blower fan only runs during a heat cycle.
If your gas furnace won't turn off, it could be due to a faulty thermostat or a problem with the furnace's limit switch. Start by checking the thermostat settings and making sure it's not set too high. If that doesn't work, try turning off the furnace at the breaker and then back on again.
When a furnace runs constantly, it probably means that something is dirty or clogged. The filter is the first thing you want to check, especially if you do not replace your filter as often as recommended (once a month during the heating season).
If your thermostat is off but heat is still on, you are probably experiencing some kind of "short" or connection issue. Most often with this problem is that a wire is touching something it should not be touching. Another possibility is that the gas valve is stuck open. This is rare, but it can happen. If.
If your heating doesn't turn off, the issue probably lies with the programmer/timer/thermostat, which may be different units or part of the same unit.
Malfunctioning Thermostat or Incorrect Thermostat Setting
Your furnace could be running constantly because either your thermostat isn't set correctly or is malfunctioning and not properly signaling the furnace when to turn on and off.
The main body of your furnace will have an electrical panel that contains the internal control settings. This is where you will turn off the furnace completely. There's often a difference between changing the thermostat over to cooling and actually turning your furnace off completely.
One of the most common issues is the thermostat. The wiring, switches, or heating sensors can fail on your unit. If this is the case, then you'll need to replace the thermostat with a newer model. A damaged primary controller can also cause the furnace to stay turned on.
During the coldest days in winter, it is normal for a furnace to run almost constantly to keep the home warm. As long as the furnace is running efficiently and not making strange noises, the constant operation is likely nothing to worry about. But in general, your furnace should not constantly be running.
Malfunctions affecting different system components can prevent the conditioner unit from shutting down as expected, such as a clogged air filter, a frozen evaporator coil, a faulty electrical relay switch, a dirty condenser coil, a constantly blowing fan, a bad thermostat, low refrigerant, and other HVAC system repair ...
Faulty thermostat.
Old wiring or dead batteries: Replace batteries or old wiring to ensure accurate temperature readings. Thermostat location: If your thermostat is too close to a heat source (like sunlight or a heat register), it can misread the temperature and cause your furnace to keep shutting off.
With all that being said, if there are no extreme factors involved, the average run time for a furnace is 10-15 minutes per cycle. Your furnace may need to run two to three times an hour to maintain your desired temperature if your home has average insulation.
If you select the “on” mode for your furnace's fan, the blower will keep running. This problem has a simple fix. Either turn the fan to “off” mode, or set it to “auto” so it only runs when the furnace is turned on.
The short answer is your furnace won't turn off due to some kind of error or malfunction within your furnace, thermostat, or HVAC system. It could be the wrong thermostat setting is being used, a clogged air filter or your thermostat itself is no longer working properly.
"Your system's [furnaces] aren't designed to run in temperatures that are below-zero for long periods of times," Marchand said. To help alleviate some of the stress off of systems during these cold temperatures, set your thermostat a few degrees lower than what you're used to.
Valve Malfunctions: Specifically, motorised valves can become stuck in the open position, keeping the heating on. Internal Wiring: Faulty internal wiring can prevent the boiler from receiving the correct signals. Boiler Pressure Problems: High or low pressure can affect the boiler's ability to turn off properly.
If your thermostat is not working properly, it may not be able to accurately read the temperature in your home or properly communicate with your furnace. This can cause your furnace to run continuously, even if your home is already at the desired temperature.
If your furnace has power controls linked to the thermostat, ensure to turn it down or switch it off. You should also visit the electrical panels on the body of your furnace to find its internal control settings. Turning it off or switching it to the coolest possible setting may already cycle the furnace off.
A faulty thermostat can cause your heating unit to run and not turn off. The unit may have a broken heating sensor, the wiring may have gone bad, or the switch itself may have broken. The older the thermostat is, the more at risk you are for this happening. Fortunately, a broken thermostat is an extremely easy fix.
There are two places you can cut the power to your heating unit: at the breaker box and at its specific power switch. Head to your breaker box and locate the breaker labeled “furnace.” Push the breaker switch to the right to shut off power.
One of the most common complaints among homeowners who possess a furnace is that their unit runs continuously. Unless you also have a heat pump (which can cause your unit to run frequently to maintain a set temperature during extremely cold weather), your furnace should cycle on and off at regular intervals.