What is Air Source Heat Pump Cascade Systems?
As the demand for efficient and eco-friendly heating solutions grows, air source heat pumps have emerged as a reliable alternative for residential and commercial spaces.
Air-source heat pumps can provide a more energy-efficient alternative for traditional heating systems in homes and have proven to be a reliable home heating method.
The operation of an air-source heat pump heating system is slightly different from traditional heating systems because they extract and release heat at a slower rate and lower temperature.
This means that heat pump heating systems may need to run for longer periods to achieve the same desired heating effect. Air-source heat pumps should be paired with large surface area equipment, such as underfloor heating and larger modern radiators, to effectively distribute heat throughout the entire house.
If the outdoor unit is appropriately sized, and enough heating systems are installed indoors, air-source heat pumps can heat the entire house. The size of the heat pump required for heating the house can be determined by several factors, including the size of the house area.
The air-source heat pump unit provides heating and hot water for our entire family.
It was installed during the construction of the house, so the sizes of the external heat pump unit and the internal equipment shown above are suitable for the size of the house.
In this article, we will discuss in detail how air-source heat pumps provide heating for the entire house, explaining the working principle of air-source heat pumps, the importance of selecting the appropriate size heat pump, and the factors that determine its size.
You may have been confused about the need for air handlers or “heads” in each room with a ductless heat pump. However, that’s not the case.
Depending on the structural enclosure and airflow of the house, a single main unit may be sufficient to heat a 1500 square feet house. However, older buildings with further separated compartments may still require a ductless heat pump unit. If your home has an open floor plan, and you want to leave doors open, you can also benefit from a ductless system.
Insulation
If the house is poorly insulated, any air-source heat pump system will struggle to warm your home. Therefore, you may encounter problems in both hot or cold regions. If the house is well-insulated and allows free airflow, a single-head ductless unit will easily heat a space of 1300 square feet in both winter and summer. Insulation ensures less heat loss. Thus, the generated heat is contained within your home and circulated normally.
Inverter Technology
Another reason air-source heat pumps can provide heating for the entire house is the adoption of variable frequency heat pump technology. When traditional furnaces fail due to extreme cold, air-source heat pumps with inverter technology will thrive. Thus, you can expect the ductless heat pump to work throughout.
However, this does not mean it’s always running at maximum capacity. Instead, the fan keeps running, rotating, and cleaning, circulating air throughout the house. This is the guarantee of having a comfortable home on cold winter days. When the outdoor temperature is 40°C and your door is open, your home will eventually reach 40°C levels. Considering the same airflow temperature from the ductless system, your house won’t warm up easily.
Nevertheless, it’s time for an internal air exchanger. Thus, if you understand the functions of the system and how to properly install them in your home, it will be helpful.
Inverter technology upgrades the heat pump, so it won’t completely shut down when your home is fully heated. Instead, it will only reduce the operating speed of the heat pump. As it’s not starting from scratch, they are very helpful in improving efficiency. Therefore, you don’t need to start the heat pump later while heating your home, so you can start heating the house from the beginning.
Moreover, they allow the user to operate them at different frequencies. The flexible frequency driver of the DC inverter can detect the surrounding temperature and make corresponding adjustments, as it’s fully controlled by the heat pump’s compressor and motor speed.
Some manufacturers now combine two different refrigerant units into their heat pumps, creating a better system capable of reaching temperatures of 80°C.
Some significant technological advancements are worth mentioning, such as the compressor, which allows re-injection of pressurized steam into the compressor to increase the temperature. The temperature variation of the water flow in these devices can exceed 65°C.
The advantage of this technology is that it reduces the complexity of the heat pump, thereby reducing operating costs. Operating pressure increases the pressure of the compressor and lowers its refrigerant threshold.
The amount of heat distributed from the air-source heat pump to your home largely depends on the outdoor temperature. However, its total heat output decreases as the ambient temperature decreases.
When the outdoor temperature drops, the heating capacity of the air-source heat pump also decreases. The sizing of these pumps is usually designed to provide 80-90% of the annual heating load. This should still be able to meet 100% of your apartment’s heating needs when the temperature is above zero.
Therefore, it is advisable to have supplementary heating sources ready to cope with extremely cold outdoor weather conditions. If the air-source heat pumps start to fail, they will be allowed to make up for the shortfall.
If you do not want your home connected to natural gas and the power grid, people can purchase tanks with fuel. These have lower operating costs as they don’t run all the time, only supporting your air-source heat pump.
There’s no need to worry about air-source heat pump icing. Although this situation frequently occurs in extremely cold conditions, affecting the pipes. Similarly, this doesn’t mean you should pour antifreeze into the frozen pipes as it may exacerbate the problem.
Air-source heat pumps mechanically defrost after icing. This means most of their power is used to dissipate the heat collected inside and around the pipes.
Although this is not entirely automated, please check the user manual to see if you can start the defrosting process manually. If all other methods fail, contact the heat pump manufacturer for assistance. Without seeking expert help, do not attempt to correct the problem.
In new buildings, it is worth exploring the installation of air-source heat pumps for the home, especially those created with a fabric-first approach in mind. Additionally, they not only provide low-carbon heating for homes but are also reliable and have a considerable lifespan.
These pumps have few drawbacks, but high-quality air-source heat pumps can last for twenty years. When you consider the possibility of recovering part of the upfront costs through incentives, it is worth it.
Finally, if the external equipment is surrounded by ice, the system is likely in defrost mode. To avoid icing, the heat pump may temporarily enter defrost mode. When the outdoor coil ices, its defrost mechanism must melt it to prevent damage to the motors and compressors inside the outdoor pump.
When the defrost mode is on, the air temperature should be evenly distributed to prevent large temperature differences. The backup heating tape and the heat pump can be turned on simultaneously. When the internal unit detects that the air temperature is too cold, it will activate the backup heater or furnace, while the defrost process heats the external coil.
The coil must remain free of ice to avoid damaging the motors and compressors inside the outdoor pump.
An air source heat pump can be used for cooling during warmer months or in regions with hot climates. The same heat pump that efficiently provides heating during colder months can be reversed to extract heat from the indoor air and transfer it outside, effectively cooling the indoor space.
Here’s when you should use an air source heat pump for cooling:
Warmer Seasons: As the outdoor temperatures rise and you need to cool your home, you can switch the heat pump to cooling mode. The heat pump will absorb the heat from inside your house and release it outdoors, effectively lowering the indoor temperature.
Summer Months: During the summer, when temperatures are consistently higher, an air source heat pump can provide effective cooling. It works similarly to an air conditioner but with the added benefit of being a more energy-efficient option.
Moderate Climates: Air source heat pumps are particularly suitable for areas with moderate climates, where temperatures are not excessively high. They can handle both heating and cooling demands effectively, making them a versatile solution.
Energy Efficiency: If you prioritize energy efficiency and want to reduce your carbon footprint, using an air source heat pump for cooling is a great choice. Compared to conventional air conditioners that rely on electricity to generate cooling, heat pumps transfer heat rather than generating it, making them more energy-efficient.
Dual-Functionality: One of the significant advantages of air source heat pumps is their ability to provide both heating and cooling from the same system. This dual-functionality eliminates the need for separate heating and cooling systems, saving space and installation costs.
Consistent Cooling: Air source heat pumps can maintain a more consistent indoor temperature compared to traditional air conditioners. They are less likely to cause temperature fluctuations, providing a comfortable and stable indoor environment.
It’s important to note that while air source heat pumps can provide cooling, their cooling capacity might be slightly lower than dedicated air conditioning units. Therefore, in areas with extremely high temperatures, a traditional air conditioner might be a better option for cooling during the hottest months.
To maximize the efficiency of cooling with an air source heat pump, consider the following tips:
Ensure Proper Insulation: Properly insulating your home will minimize heat gain, allowing the heat pump to cool your home more efficiently.
Use Thermostat Settings: Set your thermostat to the desired temperature and avoid turning it significantly lower, as this won’t cool the house faster but may lead to unnecessary energy consumption.
Maintain the System: Regular maintenance, such as cleaning filters and ensuring the outdoor unit is clear of debris, can help the heat pump operate at peak efficiency.
Use Shade: Keep curtains or blinds closed during the hottest parts of the day to reduce the amount of sunlight entering your home.
Overall, an air source heat pump is an excellent choice for both heating and cooling, providing energy-efficient and versatile climate control throughout the year. However, consider your specific climate, cooling needs, and the heat pump’s cooling capacity before relying solely on it for cooling during extremely hot weather.
Air source heat pumps are indeed suitable for whole-house heating. However, their suitability depends on several factors, including the size of the house, climate, and specific heating requirements.
For smaller houses or well-insulated homes in moderate climates, a properly sized air source heat pump can efficiently provide heating for the entire house. These heat pumps are designed to extract heat from the outdoor air and transfer it indoors, making them an energy-efficient alternative to traditional heating systems.
However, in larger houses or areas with colder climates, the heat pump’s size and output capacity become crucial factors. If the heat pump is undersized for the house, it may struggle to meet the heating demands during extreme cold weather, leading to reduced efficiency and increased operating time. On the other hand, an oversized heat pump may lead to unnecessary energy consumption and higher upfront costs.
For these reasons, it’s essential to have a professional HVAC technician assess your home and recommend the appropriate size and type of air source heat pump (air-to-air or air-to-water) to ensure it can efficiently heat the entire house.
Yes, additional heating sources can be used alongside an air source heat pump to complement its performance, especially during extremely cold weather. These additional heating sources act as backup systems, ensuring that your home stays warm even when the heat pump’s efficiency decreases in low temperatures.
Electric Resistance Heaters: These heaters can be installed in individual rooms or as part of a central heating system. They are relatively simple and can provide immediate heat, but they tend to be less energy-efficient and more expensive to operate than heat pumps.
Gas or Oil Furnace: In areas where natural gas or oil is available, a gas or oil furnace can be used as a backup heating system. These furnaces can quickly produce large amounts of heat, making them suitable for supplementing the heat pump during extremely cold periods.
Hydronic Heating System: A hydronic heating system, which uses hot water or steam, can work in conjunction with the heat pump to provide additional heating. This system can be integrated with radiant floor heating or baseboard radiators.
By having a backup heating system in place, you can ensure continuous and reliable heating for your home, even when outdoor temperatures drop significantly.
Is defrosting a concern for air source heat pumps?
Defrosting is a common concern for air source heat pumps, particularly during extremely cold weather when frost or ice can accumulate on the outdoor unit’s coils. When frost or ice builds up, it can impair the heat pump’s efficiency and performance.
However, modern air source heat pumps are designed with defrosting mechanisms to address this issue. The defrost cycle involves temporarily switching the heat pump into cooling mode to melt the frost or ice on the outdoor coils. The heat pump then switches back to heating mode once the coils are clear.
While defrosting is typically automatic in most heat pumps, some systems may offer manual defrost initiation options as well. If you notice excessive ice buildup or any issues with the heat pump during defrosting, it’s essential to consult the manufacturer or a professional HVAC technician for assistance.
Air source heat pumps can be a great investment, especially in new constructions or homes with excellent insulation and energy-efficient features. They provide a low-carbon heating solution and are known for their reliability and relatively long lifespan.
While high-quality air source heat pumps can last up to 20 years or more, it’s important to consider the upfront costs and potential savings over time. In many regions, there may be incentives or rebates available that can help offset some of the initial installation costs, making them more financially appealing.
Additionally, choosing an air source heat pump with a higher COP (Coefficient of Performance) or other efficiency ratings can lead to greater energy savings and reduced operating costs.
Overall, the decision to invest in an air source heat pump depends on various factors, including the local climate, the size and layout of your home, available incentives, and your long-term heating needs.
Air source heat pumps are most effective and efficient in mild to moderately cold weather. They perform optimally when the temperature difference between the indoor and outdoor air is not too extreme.
In regions with hot or moderate climates, air source heat pumps are ideal for year-round heating and cooling. They can efficiently extract heat from the outdoor air during colder months and provide cooling during warmer months, making them versatile and practical.
However, in colder climates, air source heat pumps may become less efficient as outdoor temperatures drop significantly. They might need to run longer to meet heating demands during extremely cold weather, which can affect their overall efficiency.
For such climates, it’s essential to have a backup heating system in place to ensure consistent heating during the coldest periods. This backup system can help supplement the heat pump’s performance and maintain a comfortable indoor temperature even in challenging weather conditions.
Air source heat pump prices and considerations
The cost of installing an air source heat pump can vary depending on various factors, such as the complexity of the installation, distance between the heat pump unit and the home, and the need for insulation materials.
Larger homes may require one or more larger heat pump units, which can increase the overall installation cost. However, it’s challenging to provide an exact cost estimate for installing an air source heat pump, as it depends on individual circumstances.
As a rough estimate, the basic price for an air source heat pump can start at around $6,000, and then an additional $750 per kilowatt (kW) may be added. For example, a 10kW heat pump’s price could be around $6,000 plus $7,500, resulting in a total installation cost of $13,500.
In new construction, installing an air source heat pump for a whole-house system might cost around $11,000 on average, depending on the size and specific requirements of the house.
Air source heat pumps are considered one of the most efficient and cost-effective heating options, as they significantly reduce carbon emissions and offer potential energy savings. Running these systems on green energy sources also contributes to a more environmentally friendly home.
One potential consideration is the need for occasional defrost cycles during colder weather. During defrosting, the heat pump may temporarily switch to cooling mode to melt frost or ice on the outdoor unit’s coils, which can lead to a slight reduction in heating efficiency during that time.
To ensure even temperatures during defrost mode, the supplemental heating element and the heat pump can operate simultaneously. When the indoor unit detects that the air temperature is too cold, it can activate the auxiliary heater or furnace, while the defrosting process heats the outdoor coils.
The coils must remain free of ice to avoid damage to the electric motor and compressor inside the outdoor unit.
In conclusion, using an appropriately sized air source heat pump can effectively and efficiently provide whole-house heating. With advancements in technology and the availability of efficient models, air source heat pumps continue to be a popular and eco-friendly choice for residential heating and cooling systems.
It’s important to consult with HVAC professionals and consider various factors before making a decision. By doing so, you can enjoy the benefits of a well-sized and efficient air source heat pump that meets your home’s heating needs.
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