Heat pump icing is a fairly common problem among owners of private houses or commercial facilities where this type of equipment is installed for heating systems. Why? Most often, icing occurs due to low external temperatures, but there are other factors that can lead to such a problem. The defrosting cycle on a heat pump allows you to efficiently and quickly solve this difficult task. However, if the equipment is faulty, icing cannot be avoided when the air temperature drops. This can lead to serious consequences, such as a decrease in equipment efficiency or damage.

Why heat pumps freeze: Common reasons

Frosting of heat pumps can occur for several reasons:

  • Low temperatures. Some users mistakenly believe that heat pumps can only freeze when it is an extremely cold winter. However, when the air temperature drops below 0°C, moisture in the device condenses and can turn into ice.
  • Incorrectly adjusted thermostats can cause the heat pump to run continuously, leaving no time for defrosting.
  • An insufficient amount of freon can lead to a decrease in pressure and temperature. Consequently, frost or ice may form on the heat exchanger.
  • Clogged air or water filters can restrict the flow of air or water through the heat exchanger, which can also cause freezing.
  • An incorrectly selected heat pump (in accordance with the needs of the house) may work inefficiently, ultimately resulting in freezing.
  • Errors during installation. If the heat pump is not installed correctly, it can lead to air or water leaks, which can also cause icing.
  • Among other factors that can speed up the icing process are unfavorable weather conditions, such as high humidity and strong winds.

As you can see from the above list, there are many different factors that can cause a heat pump to freeze. Even if the equipment is new, there is a possibility of non-compliance with the operating instructions, and such equipment may also fail due to icing. Therefore, it is essential to know what to do if this problem occurs and how to correctly defrost the heat pump.

How does the defrost cycle work?

During the cold season, a thin layer of ice may form on the external heat exchangers of the heat pump. This occurs when the condensate from the heating process freezes on the coils. To address this, the heat pump is equipped with a built-in defrost cycle, which is activated periodically to remove frost and ice.

Here’s how the defrost cycle works:

  1. Sensors on the heat exchanger detect when the temperature drops below a certain level (usually around 0°C).
  2. The cycle begins by turning on the heating elements.
  3. The heating elements generate heat, which in turn melts the ice and frost on the heat exchanger (defrosting).
  4. Once the sensors detect that the ice is completely thawed, the defrost cycle is turned off.
  5. The heat pump then returns to heating mode, resuming its normal operation.

Please note that the type of defrost cycle used may vary depending on the model of the heat pump.

Here are some important things to know about the defrost cycle:

  • The defrost cycle typically lasts between 15 and 30 minutes.
  • The frequency of defrost cycles depends on factors such as ambient temperature, humidity, and other conditions.
  • It is worth noting that the defrost cycle can slightly reduce the heat pump’s efficiency for a short period of time.

To ensure that the defrost cycle works correctly and efficiently, it is important to regularly maintain the heat pump.

Why the defrost cycle does not work: The main reasons

Why the defrost cycle of the heat pump may not work:

  1. Faulty sensor: It may not be sending the correct signal to the heat pump controller, resulting in the defrost cycle not being activated.
  2. Controller failure.
  3. Failure of the defroster coil unit: This unit performs important functions such as defrosting (heating the coil to melt ice and frost on the heat exchanger) and draining (removing melted water from the heat exchanger). The main reasons for the malfunction of this part can be a burned-out heating element, housing damage, a malfunctioning thermostat, or electricity problems. The most common signs of failure are ice and frost on the heat exchanger, reduced heating efficiency, leaking melted water, noise during equipment operation, or odors.
  4. Malfunction of the defrost relay.
  5. Malfunction of defrost cycle components: Heating elements, fans, or compressors.
  6. Incorrect installation of the heat pump: For example, if the heat exchanger is not installed at the correct angle, water can accumulate in it, leading to icing and issues with the defrost cycle.
  7. External factors: Strong wind or snowfall can make it difficult for the defrost cycle to work.

If you suspect that your heat pump is experiencing issues with the defrost cycle, contact a qualified heat pump service professional to diagnose and repair the equipment.

How to defrost a heat pump?

Experts recommend that homeowners don’t attempt to defrost a heat pump on their own. This task requires specific skills and tools. However, if you are unable to call a specialist, you can try to defrost the equipment manually.

Here are some effective methods for manually defrosting a heat pump:

  • Shut down the heat pump: Turn off the equipment and allow it to naturally defrost for several hours.
  • Use hot water: Carefully pour hot water (not boiling water) onto the heat exchanger to melt the ice.
  • Use a hair dryer: Gently direct a stream of warm air from a hair dryer onto the heat exchanger until it defrosts.

If your heat pump refuses to defrost, don’t hesitate to contact Rocky Mountain Heating and Air for assistance. Otherwise, you risk not only decreasing the efficiency of your heating system but also causing serious damage to the equipment. Experienced specialists have the necessary skills and knowledge to identify the cause of the equipment malfunction and fix it professionally. Don’t attempt to defrost the heat pump yourself if the previously performed manual methods did not produce the desired effect. Trust the professionals.

Repair of heat pumps

During winter, the heat pump becomes a reliable ally in the battle against the cold. However, if the heat pump is not defrosted, you risk causing serious damage to the equipment and jeopardizing the safety of yourself and your loved ones.

Defrosting the heat pump should be carried out by experienced specialists. The professionals at Rocky Mountain Heating and Air provide home heating and air conditioning repair services in Salt Lake City, Utah, USA, and up to 25 km outside the city. You can order an online consultation or call a specialist to your home or any other facility that requires heating system component repairs, including heat pumps, by following the link

Our advantages include:

  • Over 16 years of experience in the HVAC-R field.
  • We respond quickly and are prepared to assist you within 24 hours of receiving your call.
  • Selling hundreds of exclusively certified systems every year.
  • Various payment methods available.
  • Provision of service and maintenance, as well as a one-year warranty following system installation.

Our experienced technicians will promptly identify the cause of the defrost cycle malfunction in your heat pump, perform professional repairs using only high-quality parts, and ensure the smooth operation of your heating system throughout the winter season.