Why does my furnace light up and then shut off?
Having a dirty air filter in your furnace can cause short cycling. While a faulty flame sensor will lead to an immediate shut-off, a dirty filter will allow your furnace to run for several minutes and then shut down. You might notice that the air being pumped out of the heat grates is significantly hotter than normal.
What would cause a gas furnace to cycle on and off?
When gas gets built up in a new furnace it may shut down for extended periods of time until it can be reset to try again. Some older furnaces may not have this and could cycle off and on as gas is built up. This switch turns your furnace off if gases are not properly ventilated out of the exhaust flue.
Why does my gas furnace keep shutting off?
If your furnace keeps shutting off, it could be due to low airflow. There are several indirect issues that cause low airflow. Dirty Air Filters. If you don’t change your air filters often enough, the filters will become dirty and clogged, which means the heat exchanger retains heat and eventually causes it to overheat.
Why does my furnace keep shutting off after a few seconds?
A common reason a furnace short cycles is because the heat exchanger, the part that heats your air, is getting too hot due to a lack of airflow. Once the heat exchanger overheats, it trips the high limit switch, which shuts the furnace down to protect it.
Why does my furnace turns off before reaching temperature?
A lack of airflow can cause your furnace to stop heating before reaching the set temperature. Ensure there is nothing impeding airflow around your furnace, within your furnace and through your ducts. Check that registers are open, no ducts are damaged or crushed and replace your furnace filter.
How do you fix a short cycle on a furnace?
Quote from the video:
Quote from Youtube video: It's a dirty flame sensor. And I'll show you the steps to clean it you're gonna have to take off the cover to get to the burners. Turn the furnace off and on this model I had to remove two screws.
Can a bad thermostat cause short cycling?
Your thermostat could also cause the HVAC system to cycle on and off rapidly, a process known as short cycling. Your furnace or central air conditioner spends a good amount of energy simply turning on and off, which is why you want yours to run for at least 15 minutes at a time before shutting off.
Can a bad flame sensor cause short cycling?
Bad Flame Sensor
Flame sensors are also subject to corrosion. This is because your furnace produces small amounts of water during the heating cycle. Over time, this can lead to corrosion and rust in your furnace, resulting in short cycling.
Can a dirty flame sensor cause short cycling?
Deterioration to Flame Sensors. During the heating process, when your furnace burns fuel, the system will produce small amounts of water. This overtime can cause metals to corrode and rust. As a result, corrosion buildup triggers frequent short cycling of your furnace which can be detrimental to the safety of your home …
How long should furnace run before shutting off?
If your furnace is operating correctly, it should cycle about 2 to 3 times per hour. How long it operates depends on how cold it is outside. In milder temperatures, it may run for 10 to 15 minutes. The colder it gets, the longer the run cycle will be.
How do you test a flame sensor?
Quote from the video:
Quote from Youtube video: And connect one of the probes. Coming off the meter to the wire that you just disconnected. You're going to stick the probe between the insulation. And the back of the clip.
Where is the flame sensor on a gas furnace?
Quote from the video:
Quote from Youtube video: So the right side of the furnace.
How much does it cost to replace a furnace flame sensor?
It stops your furnace from letting off large amounts of natural gas if it’s not working properly. If the sensor is bad, it won’t be able to sense heat and will turn the furnace off. The average cost to repair or replace a flame sensor is between $75–$200.
What do flame sensors look like?
The flame sensor on your furnace is an important but simple part. It will look like a thin metallic rod and is set in front of the pilot flame on the interior of your furnace. Both of these parts can be located inside of the burner assembly of your furnace which is typically in the bottom of your furnace.
