What causes heater short cycling and how can it be fixed?

One of the most common heating repair calls our team receives is for heater short cycling. Essentially, this is where a furnace, heat pump, or ductless system is constantly starting and stopping operation. In most cases, this not only wastes energy, but also puts additional strain on the system itself.

In this article, we’ll review what short cycling is, why it matters, what the common causes of this problem are, and what you should do to address this issue if you suspect your system is experiencing this fault.

A technician looks inside a furnace experiencing heater short cycling issues.What is heater short cycling?

In the HVAC world, a “cycle” is the period of time a system runs before shutting itself off. Cooling and heating systems running normal cycles will run until the temperature in the home has been sufficiently altered. Under normal conditions, a furnace or heat pump will cycle several times per-hour, turning back on when the temperature inside the home begins to drop again.

“Short cycling,” as can be inferred from the name, is a malfunction where the system runtimes are very short, leading the system to turn itself on and off very frequently. When short cycling, the system rarely runs for more than a few minutes at a time. If you listen for the sound of the system turning off and on again, you’ll probably hear it more than a dozen times in an hour. This is a potential sign of a short cycling system.

Does short cycling matter?

Yes. Short cycling is problematic. It may be an indicator that something is wrong with your heating system. A short-cycling unit is wasting more energy than it needs to and experiences far greater wear-and-tear than a comparable system that is running normally. In situations where your furnace, heat pump, or ductless system is running incredibly short cycles, you should bring in an experienced HVAC technician to diagnose the issue.

What causes short cycling?

The three most likely causes of furnace or heat pump cycling are improper sizing, thermostat issues, and poor insulation. Here’s what you should know about all three:

Improper sizing and installation

Most people automatically assume that, when it comes to HVAC systems, bigger is better. After all, who wouldn’t want more heating in their home? When taken at face value, it’s easy to see why most homeowners think that a furnace or heat pump with a higher capacity will heat their home more effectively and quickly.

However, it doesn’t work like that. In fact, a system that is too large for your home can lead to a number of performance and efficiency problems, including short cycling.

All heating and cooling systems are at their most efficient when running normally, maintaining the temperature of the home instead of having to significantly change it. A system that is too large for your home has trouble doing this. It will start up, run, and quickly raise the indoor temperature. Then, it will shut off: it is incapable of keeping your home’s temperature in that “sweet spot” without wildly overshooting what’s on the thermostat. The indoor temperature then drops again, and this cycle repeats. The larger furnace needs to run many, many short cycles within the hour to maintain the temperature, leading to significant energy waste.

By the way, a system that is too small for your home will often experience the opposite problem: no matter how hard it works, it will struggle to maintain the temperature of your home. This is also far from ideal, and it’s why you always want a professional HVAC technician to measure your home prior to selecting a system and having it installed.

Thermostat issues

A faulty thermostat can also be responsible for short cycling problems. The thermostat provides your furnace or heat pump with instructions about when to run, based on what the indoor temperature is. However, faulty wiring within the thermostat can often lead to poor instructions being sent to the system, which results in the heater clicking on and off repeatedly without consistently running.

If you suspect that your thermostat might be the cause of your short cycling issues, you’ll want to have a certified HVAC specialist out to your home to inspect the thermostat and its wiring. If it’s not the thermostat, the technician can at least rule it out and move on to investigate other potential issues. If it is the thermostat, it might need to be replaced with either a similar model or a new programmable thermostat.

Poor insulation and airflow

Next, try cleaning the air filter that leads to your furnace. A clogged air filter has the potential to choke off the airflow to the system, leading to a number of performance problems—including cycling issues.

Poor insulation is another potential problem that you should investigate with the help of your HVAC technician. Your heating system is more likely to cycle if your home has poor attic or wall insulation, you have major air leaks in your home, or your ducts are leaky. All homes lose some degree of their generated heat, but homes that are poorly insulated are losing this heated air so quickly that the furnace is constantly caught in the bind of having to catch up.

What is the best way to deal with this issue?

Call us today have a certified technician from our team come to your home. We offer heating repair here in Fresno and the Central Valley. At Allbritten, our experienced, friendly technicians fix all heating systems, makes, and models. We’ll diagnose the issue with your heater and get it back to heating your home efficiently and effectively.

Prevent future issues with water heater maintenance this winter

Left to its own devices, your home’s water heater will likely continue to provide your home with hot water. However, did you know that preventative water heater maintenance can lower your energy costs and help you avoid water heater issues down the road? In about 30 minutes, you can quickly maintain your water heater and ensure that it continues to operate safely and effectively.

Allbritten is here for all your water heater repair and plumbing service needs. For service throughout Fresno and the Central Valley, call us today.

Flush your water heater

Throughout the year, sediment and corrosion begin to collect at the bottom of the water heater’s tank. When enough of this material is present in the tank, it can begin to have a negative impact on its energy efficiency by blocking the heating element from effectively heating the tank’s water. The best way to remove this built up sediment is by flushing your water heater at least once-per-year.

An Allbritten technician performs water heater maintenance on a water heater here in Fresno, CA.First, you’ll want to turn the water heater off and turn off the power (gas or electricity, depending on what type of system you have) to the water heater. Then, turn off the cold water intake valve. Inside your home, have one of the faucets running hot water. Connect a hose to the valve at the bottom of the water heater tank, and have that hose routed to a large bucket or barrel that can hold the water from the tank. Drain the tank and—once empty—turn that cold water supply back on and run it through the tank to wash out any remaining sediment.

Once this process has been completed, close the valve and move onto the next step: testing your water heater’s pressure-relief valve.

Check the pressure-relief valve

The emergency pressure-relief valve is a critical safety component for your water heater. The water inside of the water heater tank is held under pressure. If this pressure starts to climb—usually, due to the water temperature rising—the purpose of the pressure-relief valve is to release air and water from inside the tank to lower the internal pressure back down to acceptable levels.

For obvious reasons, a faulty pressure-relief valve is bad news for your water heater tank. Without the ability to discharge it, pressure can build to the point of the tank bursting open, flooding your home with water.

As a homeowner, you should double-check that this valve is working at least once every year. All you need to do is position a bucket beneath the valve and then flip it to the open position. Hot water from the tank should come out of the valve. If it doesn’t, there’s a good chance that something is wrong with the valve and that it needs to be replaced. You’ll need to bring in a professional plumber for help with this task.

Make sure that you end this test by moving the valve back to the closed position.

Inspect the anode rod

Your water heater’s anode rod plays a crucial role in protecting the longevity of your water heater. The anode rod attracts and collects corrosion away from the inside walls and heating element of the tank. Over time, this rust starts to eat away at the rod. A spent anode rod will look as if it has dissolved away.

If your anode rod has been dissolved, it’s a good sign that your water heater might be nearing the end of its life and need to be replaced. Without the sacrificial anode rod in place, the corrosion and rust will start to impact the rest of the system over time. In the event your water heater’s anode rod is still mostly intact, however, you might want to talk to a local plumber about having a new anode rod installed in its place. Doing so can help prolong the life of your water heater.

For water heater maintenance here in Fresno, call us

At Allbritten, our plumbing team specializes in water heater service and replacement. We assist local homeowners here in Fresno and the Central Valley with their water heater maintenance needs. If you need us to repair or maintain your water heater, call us today. We’re ready to help!