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How Heat Pumps Work and Why They Struggle in Colder Temperatures

Imagine a magic machine that pulls warmth from the air itself, even on chilly days. That’s the basic idea behind a heat pump, a versatile technology that can both heat and cool your home. But there are limits to its abilities, especially when the mercury dips below the 40s.

Let’s explore the heat pump and how it works:

  1. The Refrigerant Shuffle: Inside the heat pump is a liquid called “refrigerant”. This flexible liquid gets cold when it expands and hot when it’s compressed. Think of it like a thermal yo-yo.
  2. Heat From the Air (or Ground): In heating mode, the refrigerant circulates through an outdoor coil, absorbing heat from the outside air (even if it’s chilly!). 
  3. Compression Station: The refrigerant then gets pumped into a compressor, which squeezes and concentrates the heat. This makes the refrigerant nice and toasty.
  4. Warmth on Tap: The super-heated refrigerant flows through an indoor coil, transferring its warmth to your home through air ducts.

But here’s the catch: As the outdoor temperature drops, the magic starts to fade. Cold air holds less heat, making it harder for the refrigerant to extract enough to keep your home as warm as most people like, in the upper 60s to low 70s. Think of trying to squeeze warmth out of a snowball – not an easy feat!

The Deep Freeze Blues: When temperatures stay below freezing for days, the heat pump faces an even bigger challenge. Ice and frost can build up on the outdoor coil, acting like a thermal blanket that further hinders heat absorption. This forces the compressor to briefly reverse its operation into AC mode which will heat up to defrost the outside coil (but also briefly cools the home).

So, are heat pumps a bust in cold climates?

Not necessarily! They can still be an efficient and eco-friendly option, especially in milder regions. But if you live in areas with prolonged periods of freezing temperatures, consider these tips:

  • Pair your heat pump with a backup heating system: A furnace or boiler can kick in when the heat pump struggles, ensuring a toasty home even during Arctic blasts.
  • Regular maintenance: Keeping your heat pump in tip-top shape is crucial for optimal performance, especially in challenging conditions.
  • Upgrade your insulation: A well-sealed home reduces heat loss, making it easier for your heat pump to maintain comfortable temperatures.

Remember, heat pumps are like thermal superheroes – powerful but with limitations. Understanding their strengths and weaknesses can help you make informed decisions and stay warm and cozy all year round, even when the winter wind howls.

In addition to the above, here are some additional points to consider:

  • Heat pumps are typically rated for their efficiency at a specific outdoor temperature, usually around 47°F (8°C). This is known as the coefficient of performance (COP). The COP will decrease as the outdoor temperature drops below this point.
  • Newer heat pump models are equipped with advanced technologies that can improve their performance in cold weather, such as variable-speed compressors and cold weather start kits.
  • If you are considering installing a heat pump, it is important to consult with a qualified HVAC contractor like TemperaturePro San Antonio to determine if it is the right choice for your home and climate.