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How Do Heat Pumps Perform in Sub Zero Weather?

Modern heat pumps are designed to perform well in sub-zero weather conditions. For instance, Daikin has a range of heat pump systems that are specifically designed for cold climates. These systems are designed to operate efficiently even in extreme cold weather conditions, providing reliable and consistent heating for homes and businesses.

Daikin heat pumps use advanced inverter technology and variable-speed compressors to optimize their performance, ensuring that they can provide heat even when temperatures drop well below freezing. Additionally, most modern heat pump systems use a "defrost" mode to prevent ice build-up on the outdoor unit, further enhancing their performance in cold weather.

Some reports from those in the fossil fuel industry may state that heat pumps are ineffective or inefficient in sub-zero weather. The fact is that heat pumps extract heat from outdoor air. That heat still exists in sub zero temperatures. Many low temp heat pumps are rated at 80% output at -13F degrees. It is also important to note that they also have built-in technology to ensure that they continue to operate efficiently even in such extreme cold weather. 

One factor that can impact a heat pump's performance in cold weather is how much extra capacity is available. Proper sizing is critical. A heat pump that is sized to be barely adequate for a given space may struggle to keep up with heating demands in very cold temperatures. Plus, a unit running at 100% of its output is not as efficient as a larger one that is throttled back. For this reason (if the budget allows), we prefer to install slightly larger systems rather than the bare minimum. This promotes better efficiency and the extra capacity is available in cold weather.


Additionally, the quality and design of the heat pump system, including the type of refrigerant used, can impact its performance in cold weather. Therefore we strongly recommend that your heat pump be produced by one of the top three manufacturers - Mitsubishi, Fujitsu or Daikin.


However, many modern heat pump systems, including those designed by Daikin and other reputable manufacturers, are specifically engineered to perform well in sub-zero weather. These systems incorporate advanced technologies and features that allow them to extract heat from even very cold air, making them a reliable and efficient heating option for cold climates like Maine.

It's important to work with a qualified HVAC contractor who can help select the right heat pump system for a specific space and ensure that it's properly sized, installed, and maintained to ensure optimal performance even in cold weather conditions. 

Do I need a secondary heat source?

Efficiency Maine’s official position is “no”, however MCHP recommends having some form of supplemental heat ‘just in case’. This is often a wood stove, gas fireplace or even some electric baseboard. If your heat pump is properly sized such secondary heat sources will rarely, if ever, be used. Still, they provide peace of mind - much like an insurance policy that you hope to never use.



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