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Understanding Efficiency Ratings for Ductless Heat Pumps and the Importance of Routine Maintenance

Ductless heat pumps offer one of the most efficient ways to heat and cool your home. They eliminate the energy losses that are associated with ductwork and can provide heating at efficiencies that are far above those offered by even high-efficiency furnaces. However, there is some variation from model to model, so before shopping around you'll want to make sure you understand the different heat pump efficiency ratings for heating and cooling, and how they can be maintained through routine system maintenance.

Heat Pump Efficiency Ratings: Heating Season

If you're familiar with furnace efficiency ratings, you'll recall that they are rated by their annual fuel utilization efficiency (AFUE), which describes what portion of the energy in the fuel they consume that gets turned into heat. However, since heat pumps don't need to use fuel to create heat, AFUE is not used as one of the heat pump efficiency ratings.

The rating that will tell you how efficiently your ductless heat pump will work this winter is the heating seasonal performance factor or HSPF. It's determined by tests and calculations that are performed in accordance to guidelines set by the Air-Conditioning, Heating and Refrigeration Institute (AHRI). HSPF tells you how much heating a heat pump will provide as compared to its electricity consumption over the course of the heating season. More efficient heat pumps have higher HSPF ratings.

There are a couple ways heat pumps provide heat to your home, but the HSPF takes them both into account. On cooler days, a heat pump keeps your home warm by extracting heat from the outside air and depositing it into your home's air. But, when the temperature gets low enough, the heat pump has to provide additional heat to the home with a backup heating element. The HSPF essentially averages the different efficiencies of the two heating methods to provide an accurate picture of the efficiency over the whole heating season.

Heat Pump Efficiency Ratings: Cooling Season

With respect to cooling efficiency, heat pumps operate the same as air conditioners, so the same ratings are used. The main measure of cooling efficiency is the seasonal energy efficiency ratio or SEER. It's similar to the HSPF in that it compares the amount of cooling that a heat pump will provide to the amount of electricity it will use over the course of the cooling season. This rating is also earned according to guidelines set by the AHRI, and higher numbers are indicative of more efficient performance.

When shopping for a heat pump, you may also notice the energy efficiency ratio or EER. It is an older efficiency ratio that doesn't include the energy it takes a heat pump to cycle on and off like SEER does. However, it can be a better indicator of efficiency in especially hot weather. This is because it is calculated based on higher outdoor temperatures than SEER is.

Other Heat Pump Efficiency Ratings

If comparing all these ratings among all of the heat pumps that are available seems like a lot of work, don't worry, Energy Star makes it easy to spot efficient heat pumps. Energy Star certified heat pumps meet strict standards set by the Environmental Protection Agency, so you can rest assured they are significantly more efficient than the standard models. The Energy Star label can also be useful for getting idea of how much money you'll save on energy bills, as it usually contains information about how much it will cost to operate the appliance over the course of a year.

Another heat pump efficiency rating is the Consortium for Energy Efficiency, or CEE, Tier rating. The CEE Tier rating is similar to the Energy Star certification, but also includes a higher tier for even more efficient heat pumps. For packaged heat pumps, the CEE Tier One has the same standards as required for Energy Star certification: 14 SEER, 11 EER and 8 HSPF. For CEE Tier 2 the minimum EER required of packaged heat pumps increases to 12.

The ratings required for Energy Star certification and CEE Tier One for split heat pumps are different. Energy Star requires a minimum 14.5 SEER, 12 EER and 8.2 HSPF. CEE Tier One increases the requirement for HSPF to 8.5. For CEE Tier Two the requirements for SEER and EER increase to 14.5 and 12.5 respectively.

The Role of Routine Maintenance

It's important to remember that ductless heat pumps, like any other heating and cooling system, cannot live up to their efficiency expectations without proper care. Professional ductless mini split maintenance should be performed seasonally by a qualified HVAC technician. Between those professional service calls, you can do a number of simple preventive maintenance tasks to ensure the system continues to run at maximum efficiency.

Professional Ductless Maintenance

Professional inspection, cleaning and maintenance is essential to maximizing the performance and efficiency of your ductless mini spit system. You'll want to choose one reliable contractor – one with extensive experience with ductless mini split maintenance and repairs – to service your system regularly. This will keep your energy costs in check and reduce risk of system malfunctions or breakdowns.

The maintenance tasks you should expect your HVAC technician to complete during a service call include:

  • Inspection of evaporator coils in indoor air handler units, with professional coil cleaning done at least every other year
  • Inspection and cleaning of condensate pans and drains
  • Maintenance of fan blower wheel and blower assemblies, including checking these components for proper balance and function
  • Measurement of airflow to ensure efficient heating and/or cooling
  • Maintenance of any indoor air quality components included in your system
  • Inspection and maintenance of the outdoor unit, or condenser, including a check for leaks or damage, testing of refrigerant levels, cleaning of condenser coils and testing of system controls and general operation

Homeowner Ductless Mini Split Maintenance Tasks

Once your HVAC technician has fine-tuned the performance of your ductless mini split system, there are a number of simple maintenance tasks you can and should do to keep it in top condition. Among the most important of these are:

  • Checking over the condenser unit and its immediate area regularly to ensure proper airflow. Tall weeds or shrubbery growing around the unit restrict airflow, reducing system efficiency, so maintain at least four feet of clear space around the unit. Also, check for debris on or around the unit that can obstruct airflow, such as grass clippings, fallen leaves or a buildup of ice or snow.
  • Keep air filters clean, since dirty ones can also restrict airflow, making your system less efficient. Additionally, dust-clogged air filters aren't very efficient in protecting your equipment from dust and dirt that can cause excess wear and shorten its lifespan. Check air filters once a month, and when they appear soiled, replace disposable filters or clean reusable ones as per manufacturers instructions. Typically, they will require changing or cleaning at least once every 60 days.

DIY Ductless Mini Split Maintenance: A Troubleshooting Opportunity

For the homeowner, performing these simple ductless mini split maintenance tasks has other benefits besides protecting the efficiency of the system. Those monthly tasks allow an opportunity become familiar with the system, able to recognize small problems early and call an HVAC technician to repair them before they turn into larger and more expensive ones. Among the signs of trouble homeowners should be watching for are:

  • Mold growth on the evaporator coils or condensate pans (indoor unit or units)
  • Signs of moisture around the indoor unit or units, indicating a drainage problem
  • Excessive ice buildup on condenser coils (outdoor unit) that may indicate a problem with the system's defrost cycle
  • An increase in noise or abnormal noises from the condenser unit during regular operation
  • A marked decrease in heating or cooling performance

If you need an experienced, reliable HVAC contractor for regular ductless mini split maintenance, or if you have questions about ductless efficiency ratings, please contact us to find a factory trained and certified Mitsubishi Electric Contractor in your area.

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