Why does my furnace shut off and then come back on?
When a furnace keeps turning on and off, it is usually due to short cycling. This is the term used to describe problems originating from within the heating system. If short cycling is not promptly diagnosed and corrected, it could cause permanent damage to your heating unit and higher utility bills.
Why does my furnace keep short cycling?
A dirty air filter is the most common cause of short-cycling. If your air filter is clogged with dirt, it won’t allow proper air flow to the heat exchanger. That can cause the furnace to overheat and forces the high limit switch to ride to the rescue by shutting the furnace off.
Why does my furnace keep shutting off after a few minutes?
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.
Can a faulty thermostat cause short cycling?
A faulty thermostat can be a possible culprit for short cycling. If you’re experiencing a furnace short cycling, the first and easy thing you can do is check your thermostat to see if it’s performing correctly. Many times, a homeowner may forget to switch their thermostat over to the heating mode.
How often should a furnace cycle on and off?
3-8 times per hour
On average, furnaces should kick on and off anywhere from 3-8 times per hour. However, if your furnace does so more frequently, don’t assume it’s short cycling just yet.
Why does my furnace come on every 5 minutes?
Short cycle time: 2-5 minutes.
Your furnace has a part called a high-limit switch. If the furnace gets too hot, the switch shuts down the furnace. A dirty filter prevents a flow of fresh, cool air into the furnace to be heated and dispersed.
How do you fix short cycling?
How To Stop and Prevent Short-Cycling
- Check your air filter. Believe it or not, a clogged air filter can cause a wide variety of air conditioning issues. …
- Check your thermostat placement. …
- Check your air conditioner’s refrigerant levels. …
- Replace the low-pressure control switch. …
- Check the compressor.
How long should a furnace run between cycles?
10-15 minutes
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.
How do you know a thermostat is bad?
7 Ways to Tell Your Thermostat Is Broken
- Thermostat Has No Power. …
- AC or Furnace Won’t Turn On. …
- Heater or AC Won’t Turn Off. …
- Thermostat Doesn’t Match Room Temperature. …
- Thermostat Doesn’t Respond. …
- Short Cycling. …
- Thermostat Forgets Programmed Settings.
Can a dirty filter cause a furnace to short cycle?
Your Furnace Filter is Dirty
A dirty filter is another reason your furnace can short cycle and overheat. If you notice that the furnace is shutting off after only a few minutes before your home is warmed this may be the cause. Another sign is that you feel hotter than usual air coming out of the heat grates.
How do you stop a furnace short cycle?
The Solution. Unfortunately, there is no repair option for an oversized furnace. In this case, the best way to prevent a furnace short cycle is to replace the system with one that fits your home.
How do I clean my furnace flame sensor?
Quote from the video:
Quote from Youtube video: So if you have a situation like this what you have 90% of the time is just a dirty flame sensor. So we'll go through the steps on how to clean it. So the right side of the furnace.
How much does it cost to replace a furnace flame sensor?
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.
How long do furnace flame sensors last?
about five years
Flame sensor lifespan
If you’ve just replaced the sensor or had a new furnace installed, you can expect the flame sensor to last for about five years. The average lifespan of a furnace is 15 to 30 years, so you can anticipate a flame sensor replacement once or twice over the course of your homeownership.
Where is furnace sensor located?
A furnace flame sensor is a very basic part of your furnace. It’s located on the burner assembly and is just a thin metallic rod. It’s usually bent, and it sits just in front of the pilot flame inside the furnace.
How do I know if my furnace flame sensor is bad?
6 Signs of a Malfunctioning Gas Furnace Flame Sensor
- Yellow Burner Flames. Open up or glance through the peephole of your gas furnace to see the color of the flames firing up in the burner. …
- Rusted Flue Lines. …
- High Utility Bills. …
- Water Leaks. …
- Old Age. …
- Constant Thermostat Adjustments.
How often should you clean your furnace flame sensor?
We usually advise that you schedule furnace maintenance every 1-2 years (ideally once a year) and duct cleaning at intervals of 3 to 5 years for a smooth-running system and excellent indoor air quality. That’s the minimum.
