Here’s what heat pump cycling is and how it can be prevented

Dent Air ConditioningUncategorized

Your home relies on its heat pump for efficient, year-round comfort. But, lately, things have changed: your energy bills are up, your home is experiencing major temperature swings, and you’ve noticed the sound of the system turning itself on-and-off throughout the night. Chances are that your system is experiencing an issue known as heat pump cycling. Instead of running consistently, the heat pump constantly turns on and off. 

This is more than just an annoyance: short cycling can lead to higher energy costs, additional wear-and-tear on your heat pump, and reduced comfort in your home.

Short cycling issues aren’t exclusive to just heat pumps. Furnaces, air conditioners, and ductless HVAC systems all can experience short cycling problems. This article discusses heat pumps in great detail, but the general principle—along with the root causes of the issue and ways to prevent it—apply to all cooling and heating systems.

You'll often hear the first signs of heat pump cycling when the outdoor unit stops and starts running constantly.

What is cycling?

We’re not talking about riding a bicycle. In the context of cooling and heating systems, “cycling” or “short cycling” refers to a pattern where the system continuously turns on and off in a short period of time instead of running consistently over a longer period of time.

Here’s an analogy that does involve a bicycle. Let’s say that you’re in a race. What is the more efficient way to get to the finish line: riding at a slower speed you can maintain for the duration of the race, or starting at an unsustainable speed and then having to stop every other mile for five minutes to rest your sore legs and catch your breath? As any competitive cyclist can tell you, the former is far more effective—and far less likely to give you cramps. 

The same basic principle applies to your heat pump: the system is able to operate most efficiently and effectively when it can run consistently. Constantly starting and stopping puts unnecessary stress on the system.

What causes cycling?

The near-constant off-and-on transition of a heat pump can be caused by a number of different factors. Here are some of the most common ones and how they can potentially be avoided:

The system is too large for your home

  • Issue: A heat pump that is oversized for your home’s square footage will most likely encounter cycling issues. It quickly cools or heats the home, but is unable to maintain the target temperature without overshooting it.
  • Prevention: During a professional estimate for a new heat pump, your technician should take accurate measurements to match your home to the right-sized system.

The thermostat is malfunctioning

  • Issue: If the heat pump and your thermostat are not communicating properly, the latter could erroneously send the system the signal to shut off prematurely. This prevents the heat pump from maintaining the temperature needed in the home.
  • Prevention: During a seasonal tune-up for your heat pump, your technician will confirm that these systems are talking to each other properly.

Airflow to the heat pump is blocked

  • Issue: Heat pumps need to intake air from your home and then distribute it out to each room through the ducts. Airflow issues can lead to cycling as the heat pump cannot regulate a consistent temperature.
  • Prevention: Clean or replace your air filter regularly, and have a technician out to inspect the heat pump if the system starts cycling.

What are the consequences of cycling?

While short cycling may sound like a relatively benign issue for a heat pump to have, there are some potentially serious consequences for the system and your home, both in the short- and long-term.

  • Reduced energy-efficiency: A heat pump that is constantly turning on-and-off will expend more energy than one that is running consistently. Most modern cooling and heating systems—especially those with variable-speed motors—can maintain a home’s temperature with incredible efficiency. If the system is cycling, that advantage is lost and you’ll see the negative impact on your monthly energy bills.
  • Added wear-and-tear: Cycling puts additional wear-and-tear on heat pumps, which can ultimately reduce their effectiveness, limit their lifespan, and lead to more repair costs.
  • Poor indoor comfort: Not only is the cycling heat pump running inefficiently, but it’s also not heating or cooling your home as well as it could. Cycling systems often lead to major swings in indoor temperature, as well as hot and cold zones throughout the home.
  • Noise: Many homeowners complain about the noise generated by a cycling heat pump. These systems tend to make more noise when the start and stop than during consistent operation, so cycling is often noticeable—and obnoxious.

What are the signs that a heat pump is cycling?

If you set the temperature lower or higher and then listen to the heat pump running, you should be able to tell if it’s short cycling by counting the number of times it turns off and on throughout the hour. If the system is shutting off and then almost immediately flipping itself back on, that’s a good sign that you need to call our team.

In the summer or winter, you’ll also often feel heat pump cycling problems. In the hot months when the system is set to cool your home, you’ll notice that your home gets really cold, really fast, but that it doesn’t stay that way for long. Then, the rooms heat back up and the cycle repeats itself.

When in doubt, call an HVAC professional out to inspect your system. If short-cycling issues are caught early, you have a better chance of avoiding long-term damage to the heat pump.

Call Dent Air Conditioning for help with heat pump cycling issues

If you suspect that your heat pump is cycling, call our team at (601) 366-5338 and have one of our NATE-certified technicians out to inspect your system. You can also request service with us online.