Why Is My Heater Starting and Stopping Rapidly?

heating system

Have you ever asked, “Why does my heater keep shutting off?” You’re not alone. This is a prevalent issue that could result in higher utility bills and significant heater repairs if not promptly diagnosed and corrected.

It’s called short heater cycling if the furnace is cycling on and off.

What Is Short Cycling?

Short cycling means that your heater starts, but then it suddenly stops after a short run. It works opposite to a properly running machine that completes a full cycle.

Some of the more common explanations for why this could happen are discussed below.

Low airflow

It may be due to low airflow if your furnace keeps turning off. Many indirect problems cause inadequate airflow.

Dirty Air Filters

The filters can get dirty and clogged if you don’t change the air filters frequently enough, ensuring the heat exchanger absorbs heat and causes it to overheat eventually. Unless you have pets or allergies, you must change your air filters after every 90 days. You can change air filters after every 60 days if you have pets or allergies, or less if your allergies are severe.

Dirty Blower Wheel

It might be a dirty blower wheel if your furnace goes on and off too rapidly. The blower wheel has blades that drive the air, and it will not work as well if it has dirt on it and might eventually not work at all. By changing your air filters periodically, you can avoid dirt from piling up on your blower wheel. This could end up being expensive to fix if you don’t.

Closed or Blocked Air Supply Vents

Check your air vents if your heater keeps shutting off to see if any of them are closed or blocked in any way. It would help if you kept all your vents open, even in the rooms you don’t use. It can’t transfer enough heat if your heat exchanger doesn’t get enough air. The heat then builds up and could end up triggering the short period of your furnace.

Change Thermostat Batteries

What regulates your entire heating system is your thermostat. So, your thermostat could be malfunctioning or broken if your furnace keeps turning off and on too quickly. Many factors could cause the thermostat not to work correctly. The wiring might be old and need to be replaced, new batteries could be required, or it could be your thermostat location.

If your thermostat is mounted near a heat source, such as direct sunlight or a heat register, the temperature reading would be distorted, causing the thermostat to turn on and off irregularly. You would need to contact a professional to either fix any old wiring or shift your thermostat to a more suitable spot unless your thermostat only requires batteries.

Corroded flame sensor

This applies to gas furnaces, which are the heating system’s most common type. When the gas valve is open, the flame sensor decides if the burners are on. If it doesn’t detect fire, the sensor will shut off the gas, preventing an accumulation of unburned gas in the combustion chamber.

Oversized heater

An improper installation is the most significant problem that can cause a furnace to keep turning off. If a heater is too powerful for a house, it will heat the living rooms so quickly that the heater will be turned off prematurely by the thermostat. In this situation, all you can do is the plan for a new installation of the heating system, this time by a trained professional who can ensure the heater is the correct size.

Blocked Heat Register

If the forced-air duct registers or dampers are closed or blocked, it may cause the heater to overheat and shut down repeatedly as a safety measure. Check if these ducts are accidentally sealed by playing children or furniture nearby that has blocked them. When you find that air coming through the registers is unusually hot, this can be a sign that airflow is being obstructed.

Blocked Exhaust Vent

An exhaust vent blocked by an obstacle, such as a bird’s nest or snow and ice, is one of the more severe short-cycling causes. Exhaust gases build up in the furnace as this occurs and cause it to overheat and shut down repeatedly. If the exhaust vent is in the sidewall, check it to ensure it is free of debris. You can also fit a screen over the vent that will help prevent birds and other animals from entering inside the exhaust vent.

Why It’s Important to Fix Short Cycling

Before making any changes, it is essential to find out the exact cause of your short cycle furnace. We recommend you hire a professional when you find short cycling. Once the technician finds out the problem, he will fix it before it causes any significant issue to your heater.

The advantages of eliminating short cycling fall into three categories:

Energy-saving: – You will find a massive surge in your electricity bills due to short cycling. When the heater starts and stops rapidly, it merely means reduced energy efficiency and increased utility bills.

Safety: – Short cycling can be the sign of a larger, more severe problem. Specific persistent heater problems can endanger the safety of your family and home. To prevent critical issues in the future, it is essential to tackle any short cycling immediately.

Convenience: A short cycling heater will lead to fluctuating temperatures in your home, uncomfortable temperatures that are too hot or too cold. With extra energy costs and repairs, a malfunctioning furnace will also trigger additional financial burdens.

What should you do?

It is best to call an HVAC professional and look at your heater to know why it is running, shutting off, and then starting again. They can help fix any of the causes mentioned above or identify additional items that need repair.