Heat pumps have become quite common these days since they cut back on energy costs and are more environment-friendly.
If you’re thinking about investing in one, you’ve probably got a few questions in mind, like how expensive they are and do they help in extreme weather? We’ve prepared this detailed guide, that’ll tell you all you need to know about heat pumps!
What is a heat pump?
Like a heater or an air conditioning unit, a heat pump is a 2-in-1 cooling and heating system. It can both cool and heat a home due to its versatile, reversing valve design. Contrary to what its name may suggest, a heat pump doesn’t use up much energy to cool or warm a room.
Heat Pumps are considered to be more efficient than boilers, baseboard heaters, or forced air systems. This is because they don’t generate heat. Instead, they transport it from a cool region to a hot one. Typically, for heating purposes, a heat pump depends on energy from the outside.
The heat pump absorbs outside air (even cold air) and then transforms it into indoor air. Similarly, the device absorbs outdoor air and transfers it into indoor air, just like an air conditioning unit for cooling purposes.
Like an air conditioning unit, a heat pump is designed with several key components. These include an outdoor unit that resembles a split unit AC’s outer casing. Other components include an indoor unit, a refrigerant, compressor, reversing valve, thermostat, and expansion valve.
How does a heat pump work?
The heat pump pumps a liquid refrigerant in the expansion device to mimic an evaporator during the cooler season. This prompts air inside the house to be blown into the coils, forcing the refrigerant to absorb the heat.
This, in turn, forces cool air to be blown into the home’s ducts and into the compressor to be pressurized. The hot pressurized air is then moved to the outside unit to be cooled and pumped back to the interior to cool your home.
During the heating season, the heat pump works similarly to the way it does during cooling. However, the refrigerant’s flow is reversed to have hot air as the finished product this time around. In this case, the outdoor air is the heating source, resulting in heat energy release indoors.
Key elements involved
Made from a fan and coil, an outdoor unit involves a condenser for cooling and an evaporator for heating. To execute heat exchanges, the fan is used to blow air from outside on the coil.
Similar to the outdoor unit, an indoor unit contains a fan and coil as well. The coil functions as an evaporator and condenser, depending on the mode you want. On the other hand, the fan is responsible for supporting air transport through the coil and ducts in your home.
A refrigerant is a liquid added to the device to aid in the heat transformation. It absorbs and removes heat while it circulates through the pump.
A compressor works by pressurizing the refrigerant. This process produces pressurized air.
There are two valves in a heat pump, i.e. reversing and expansion. The reversing valve, as its name suggests, reverses the refrigerant’s flow, allowing the pump to work as both a cooler and heater. On the other hand, the expansion valve regulates the refrigerant’s flow, supporting pressure reduction and regulating the refrigerant’s temperature.
Cost of operation
Generally, heat pumps are cost-effective and affordable to run compared to other HVAC systems such as resistance heaters, furnaces, and boilers. This is because rather than generating heat, they only transfer it. After all, heat pumps simply move cool air from the outdoors to the interior during the warm season.
Heat pumps do have a limitation when it comes to their running. This is because they work best as moderate cooling and heating devices. However, if you find yourself in extreme conditions, you must pair the pump with other heat-generating systems. Doing this will obviously raise your energy bills.
Supplementary heating/cooling devices
Even with the most advanced heat pumps, you may still have to add an extra cooling or heating solution in extreme conditions. Typically, they will only work efficiently within the temperatures of 25 to 40 degrees Fahrenheit.
If you invest in a more advanced unit, add an extra 5 to 10 degrees Fahrenheit. However, you will have to add a different unit beyond these parameters, if it's too hot or too cold in your environment.
Types of Heat Pumps
Air source heat pump
Air source devices are the most common types of heat pumps because they are considered to be the most efficient. Resembling air conditioning units, air source heat pumps function by transforming heat absorbed from the outside into your home. They work the same way to cool your home.
Although air source devices depend on electricity, the renewable heat they absorb to cool or warm your home results in greater power output and minimal electricity usage.
Heat is absorbed from the air outside and transferred to a refrigerant. The refrigerant then goes through a compressor. After the compressor, the refrigerant is transported to the area which is to be heated or the central duct system. The refrigerant vaporizes the air, thus releasing heat.
Electricity is used to run the pump and compressor. However, the air source pump design means less electricity is used, and more cooled or heated air is released to make these pumps quite efficient. You will find two types of air source pumps in the market, air to water and air to air.
Air-to-water and Air-to-air
Air-to-water devices feed heat collected from outside air into a wet heating system while air-to-air pumps feed the air through fans. Air-to-water pumps are ideal for large radiators, while air-to-air pumps work best during cold and hot seasons.
A water source device functions by transferring heat using water. However, to use a water source heat pump, you need to be near a large water source, such as a lake or river. Generally, their functionality resembles that of an air source pump.
Unlike air source devices, they don’t draw warmth from the outside air. Instead, they function by extracting heat from the water through a system of pipes connected to the water source and leading back to your home. Similar to air source heat pumps, water source devices work during the cold and warm seasons. During the warm season, heat is removed from your house and released into the water source.
The water source is then used to help cool your home. But, unlike some air source devices that use fans, water source heat pumps may not be as efficient for those who live in warm climates. This is because water doesn’t get as cool.
Also known as ground source heat pumps, geothermal heat pumps use the earth’s temperature to exchange heat. This method works because the earth maintains constant temperature underneath the ground even during seasonal changes. Additionally, depending on the climate, the temperature becomes cool during the hot season and warm during the cold seasons.
This makes geothermal heat pumps quite effective and efficient. These types of pumps use ground heat exchangers instead of outdoor units to exchange the heat during different seasons. You can even find advanced models designed with different compressor and fan speeds for added efficiency and efficacy.
Benefits of Heat Pumps
- They provide both heating and cooling solutions.
- They provide clean energy (no combustion), thus, significantly reducing your carbon footprint.
- They offer renewable energy usage – they deliver an increased heat output with very little power consumption.
- They improve the quality of air in your home since they don’t involve any combustion, which may produce fumes or smoke.
- They are cost-effective since they don’t generate heat, but instead, they simply transfer it.
- They require less maintenance compared to other HVAC solutions, particularly combusting heating systems.
Drawbacks of Heat Pumps
- They may not be as efficient for extreme conditions – their yield decreases as temperatures increase or decrease.
- They are significantly more expensive to install – they involve a range of components and may require permits.
- The systems are quite large – you need a large indoor and outdoor unit.
In the right conditions, heat pumps can be pretty effective for both cooling and heating. After all, they can slash your energy bills by up to 24%. Additionally, with the increased effects of global warming, they are perfect for these times when it’s essential to cut down on our carbon footprints.