One of the more common concerns that homeowners have about heat pumps is that they won’t be efficient during the winter. While heat pumps achieve their best efficiency in cool or mild weather, they still tend to outperform electric resistance heating at temperatures above 0 degrees Fahrenheit. There are also systems with backup heating options that can easily handle the extremely cold weather that occasionally hits our part of Kansas. Here’s what to know.
How Heat Pumps Work
The operating principle of a heat pump is effectively the same as the one that drives an air conditioner. Refrigerant boils, allowing the transfer of heat from one location to another. This happens even in cold weather, although the efficiency of the process declines a bit.
Notably, the process of transporting heat via refrigerant allows you to extract warmth from sources like outdoor air, the ground, or a body of water. Even if the air outside is seemingly quite cold, it still has enough latent heat to warm your home.
A heat pump transports this latent heat inside, and this is the key to its efficiency. Rather than producing heat, like you’d see with a gas furnace or an electric heater, the heat pump merely transports the heat from one location to another. Consequently, it can do the job very efficiently compared to the electricity it needs for operation. In ideal conditions, heat pumps achieve efficiency levels of 400%-500%.
Geothermal Heating
Running heat pump lines into the ground is a simple form of geothermal energy. The Earth is significantly warmer than the air even a couple of feet down. Lines buried in the ground stay in contact with this warmth, allowing the heat pump to operate in its optimal range even during severe cold snaps.
Ductless Models
Since heat pumps use the same principle as AC units, they also can operate with a ductless mini-split. Rather than using a duct system to transport air from your HVAC, a ductless design targets individuals rooms. This is a great way to implement zoned HVAC. It also is a good way to retrofit a space, such as a newly added home office, with a heat pump.
Heat Pumps and the Cold
Modern heat pumps are highly capable of operating in cold temperatures. A typical modern heat pump remains at least 100% efficient even at 0 degrees. If your home has a model from after 2015, you can be confident that it uses the modern approach to handling cold weather.
To be clear, the idea that heat pumps can’t handle the cold is grounded in historical truth. Early models from the 20th century did struggle to efficiently heat homes in temperatures below 20 degrees. However, the industry has since radically improved cold-weather performance. Many modern models operate in heat pump-only mode down to 5 degrees, only then kicking on supplemental heating.
Notably, a heat pump’s efficiency does decline as the weather gets colder. This means there is a break-even point below zero where an electric or gas furnace would outperform a heat pump. However, this part of Kansas usually sees at most three or four nights a year when that would be the case.
Options for Fighting the Cold
It’s worth noting that there are several ways to combat this issue. Many heat pumps have a backup heat source, such as an electric furnace that kicks on to provide heat during the one or two severe cold snaps we get a year. The system detects when efficiency is declining and switches to the backup heating source automatically.
The design of your heat pump can also fight the cold. Running the tubing for the heat pump into the ground or a body of water will keep it warmer. Even when the air temperature is -15 degrees, the ground temperature will be closer to 55 degrees.
Running the lines into water or the ground isn’t always an option for folks who have smaller properties, though. In those cases, backup heating is the best way to deal with the handful of nights when your heat pump won’t be its most performant.
Setback Temperature
One quirk of running a heat pump during the winter is that using a setback temperature to improve efficiency isn’t a good idea. A setback temperature is when the thermostat uses a lower temperature to reduce demand. For example, many programmable and smart thermostats allow you to set a lower temperature for when you’re at work. This reduces the need for heating your home while there’s nobody present.
The problem for heat pump owners is that recovering from a setback temperature during extreme cold takes too much energy. Instead, the best thing to do is to choose a consistent target temperature that you find comfortable.
More Days of Efficiency
The main argument for using a heat pump as a winter heating source is that it will have vastly more days when it’ll be more efficient than a furnace or a boiler. You are basically trading a handful of days when the heat pump is less efficient due to extreme cold for several months of better efficiency.
Consider the number of winter days when the temperature outside will be 40 degrees or higher. These are the days when a heat pump’s efficiency will absolutely dominate anything else. Likewise, you get the benefit of close-optimal efficiency during the winter and spring. Even on the occasional cold summer night, your heat pump will be an extremely efficient performer.
Winter Heating Performance Ratings
One way to make sure your heat pump will be efficient during cold weather is to pay attention to two key heating performance ratings. The first is HSPF2, a rating that indicates the system’s cold-weather performance. A 7.5 rating is the minimum, and a 10.0 rating or higher indicates that the heat pump has excellent cold-climate performance.
You also want to check the unit’s heat retention capacity at 5 degrees. Ideally, the unit should retain at least 75% of heat at this temperature.
Assessing an Existing Heat Pump
If your home has a heat pump already, you may want to assess whether replacing it is a good idea. Modern models are more efficient and resilient in cold weather, even compared to models from just 10 years ago. The expected lifespan of a heat pump is usually 15-20 years, so an older model is likely due for replacement anyway.
A big sign that an existing heat pump is ready for replacement is that it starts to rely on supplemental heat at higher temperatures. If the supplemental heat activates when the outdoor temperature hits 30 degrees, then it is time to replace your heat pump.
Air Care Heating & Cooling has served the households of the Greater Kansas City area since 1981. We offer a host of residential and commercial HVAC services, including work on furnaces, boilers, heat pumps, air conditioners, and mini-splits. You can even turn to us for 24-hour emergency repair service. There are thousands of stellar reviews for our company on Facebook and Google. We offer specials regularly each month, and financing is available for installation projects upon credit approval. If you’re interested in heat pump services for a home in Shawnee, KS or any of the surrounding communities, contact Air Care Heating & Cooling today.
