Heat pumps have become a handy solution – heating and cooling all in one. But have you ever wondered how much energy a heat pump consumes and how much it costs you? Let’s break it all down.
Heat pumps can both warm and cool your home by taking heat from the outside to your home and the other way around. But how exactly do they manage it?
Step 1: Finding heat. Heat pumps absorb heat from the outside air or ground, even in cold weather. Liquid refrigerant, circulating throughout the system, passes through the outdoor heat exchanger and evaporates into a gas.
Step 2: Warming the house. The compressor squeezes the gas and passes to the indoor heat exchanger. Here, a fan blows air from your home over the coils containing the hot refrigerant, transfering the heat from the refrigerant to the air and warming your home.
Step 3: Returning refrigerant. The now cooler, lower-pressure refrigerant makes its way back outside, where it expands through a pressure-release valve. This expansion further lowers the temperature, making it ready to absorb more heat and start the cycle all over again.
Heat pumps are equipped with a reversing valve that can change the direction of refrigerant flow. In cooling mode, the magic happens in reverse: the refrigerant absorbs heat from the warm air inside your home, making it colder. The compressed, hot refrigerant then travels outside, where it releases heat into the ambient air. This cool air inside your home is then circulated throughout your house.
The key difference between a heat pump and an air conditioner is that an air conditioner can only cool the air, while a heat pump can both cool and heat. In fact, most modern air conditioners are actually heat pumps.
Figuring out your pump’s wattage can be tricky because this information might not be listed on its datasheet. Instead, you can find there different ratings:
SEER or Seasonal Energy Efficiency Ratio. This rating system tells you how efficiently a heat pump cools your home over a year. The higher the SEER, the less energy it uses. Your pump may have from about 14 to 22 SEER.
HSPF or Heating Seasonal Performance Factor. This rating applies to heat pumps and measures how efficiently they heat your home throughout the year. Just like SEER, a higher HSPF means better efficiency. Your pump may have from about 8 to 14 HSPF.
BTU or British Thermal Unit. This is a unit of energy used to measure the heating or cooling capacity of equipment. In simpler terms, it tells you how much heating or cooling power a system can deliver. Your pump may have from about 12,000 to 72,000 BTU. A 12,000 BTU unit might be suitable for a small cabin, while a 72,000 BTU unit could heat and cool a large home.
By knowing these ratings, you can guestimate how much your pump draws in both cooling and heating modes.
Let’s start with cooling. To get your pump’s consumption in cooling mode, divide BTU by SEER:
BTU / SEER = Running wattage in cooling mode
Let’s say we have a 48,000 BTU 16 SEER heat pump in cooling mode. How much power does it run on?
48,000 BTU / 16 SEER = 3,000 W or 3 kW
Now let’s find out the consumption in heating mode. For that, we’ll use HSPF instead of SEER:
BTU / HSPF = Running wattage in heating mode
Suppose we have a 36,000 BTU 9 HSPF heat pump in heating mode. How much power does it need?
36,000 BTU / 9 HSPF = 4,000 W or 4 kW
In general, heat pumps for a small cabin may consume about 0.5kWh per hour in cooling mode and about 0.8kWh per hour in heating mode. Consumption of heat pumps for large houses is much more impressive – about 5kWh per hour in cooling mode and about 9kWh per hour in heating mode.
Let’s convert kilowatts into dollars and look at the running costs. Suppose we have a small heat pump for a tiny cabin and a big pump for a large house in California with the cost of electricity being around $0.20 per kWh. How much does heating and cooling cost us?
If we run a small pump for four hours a day, we might spend about $1 a month in summer and about $2 a month in winter. With a large pump, we’ll have to pay about $30 and $60 accordingly. The consumption of heat pumps is much lower than that of electric furnaces, but can still make up a fairly large portion of your energy costs. Any ways to bring them down?
Keeping your home comfortable all year round doesn’t have to drain your wallet. Here are five tips on how to bring your heating and cooling costs down.
Heat pumps work most efficiently when maintaining a steady temperature. Constantly adjusting the thermostat for short periods can actually use more energy. Find a comfortable temperature and leave it set.
The outdoor unit of your heat pump is responsible for extracting heat or cold from the outside air. If leaves, debris, or snow block the unit, it has to work harder and use more energy. Be sure to regularly clear away any obstructions from around the unit.
Drafty windows and doors can let a lot of warm or cold air out of your home, which will make your heat pump work harder to keep you comfortable. Take some time to seal any air leaks around your windows and doors.
Choose a heat pump sized to meet your home’s specific heating and cooling needs. An oversized heat pump will short cycle, which means it will turn on and off rapidly, wasting energy and reducing efficiency.
Heat pumps and solar panels can be a great match. Combining solar panels with a heat pump can be a win-win for homeowners looking to save money, reduce their environmental impact, and achieve greater energy independence.
Depending on your pump’s power consumption, you can either run it entirely on solar power or draw a shortfall from the grid. Considering the 25% energy loss from converting the DC generated by your solar panels to the AC consumed by your home, you would need ten 400W panels to completely run a 3kW pump on solar power.
While solar panels can generate electricity during the day, heat pumps often see their highest usage during colder evening hours. This is where you might want solar batteries. By storing excess solar energy during the day, batteries can provide power to your heat pump at night, increasing your self-reliance and reducing your dependence on the grid.
Note: The difference between your solar system’s performance in summer and winter can be as much as 50%. Keep that in mind when calculating your solar system size. If you’re wondering how to start and avoid making mistakes, read our article Ultimate guide: DIY solar system kit.
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Years of experience in translation and a love of nature help Julia find the right words to encourage going solar. She joined the team in 2023 and is happy to make her contribution to a greener future.
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