Compiled by Eamonn Ryan

Heat pumps will provide one-fifth of the world’s heating needs by the end of the decade if nations follow through on their plans, according to the International Energy Agency (IEA).

Around 9.7 billion people will be living on Earth by 2050, of which70% will be located in cities.

Around 9.7 billion people will be living on Earth by 2050, of which 70% will be located in cities Frimufilms / Freepik

The significance of cooling and heating in living and working environments is going to increase significantly due to global megatrends such as globalisation, urbanisation and digitalisation.

One of the drivers of the heat pumps market is that many refrigeration systems, air conditioning systems and heat pumps still run on refrigerants whose emissions contribute to the greenhouse effect. The Kigali Amendment to the Montreal Protocol defines the international routes to transition to refrigerants with less of an impact on the greenhouse effect. Products for all key refrigerant technologies are available. This enables manufacturers of heat pumps to always use just the right components to comply with the local regulations.

Another driver is urbanisation. Around 9.7 billion people will be living on Earth by 2050, of which 70% will be located in cities, whose residential and commercial buildings and key infrastructure systems will need to be heated and/or cooled. Both functions will be combined in air-conditioning and heat pump systems – the market will be enormous.

Grant Laidlaw, owner of Air-Conditioning and Refrigeration Academy (ACRA) and past president of SAIRAC, says: “Like an air-conditioner, a heat pump uses refrigerant to move heat from one location to another. In fact, the two systems operate identically in the summer, extracting heat from inside your home and exhausting it outside.”

Grant Laidlaw. © RACA Journal

He lists the advantages and disadvantages.

Advantages:

Versatile: Smaller units offer heating and cooling and can heat water and air

Environmentally friendly: With no open flames or fumes, these risks don’t exist with an electric heat pump, making it one of the safest types of HVAC equipment. The lack of direct fossil fuel emissions also makes heat pumps more eco-friendly

Energy efficient: Even the most advanced furnace type systems or element-based systems can never be more than 100% efficient, whereas heat pumps boast an excess of 300% efficiency

Solar power: Heat pumps pair well with solar panels – if you have solar panels or are thinking of installing them, know that they are compatible with electric heat pumps

Better humidity control and air quality

 

Disadvantages

Reduced efficiency in cold weather: Effectively extracting thermal energy from outdoor air becomes increasingly difficult as the temperature drops

The need to defrost: Sub-freezing temperatures cause ice to form on the outdoor heat pump unit. This forces the system to enter defrost mode, melting the ice so it can continue operating

More noise: Longer run cycles also mean the fan and compressor are on more often in cold weather, which creates operating noise

Shorter lifespan

Higher capital and maintenance costs

Danfoss Climate Solutions panel discussion

The following Danfoss Climate Solutions (DCS) panel discussion involves:

Morten Skovrup, global application manager from Germany

Jamie Kitchen, sales account manager for North America

Morten Skovrupthe of DCS

Jörg Saar of DCS

The discussion covers the definition of a ’heat pump’ as well as the many different types and sizes, from small spilled systems up to industrial-sized heat pumps for district heating. Focus is on the heat pump itself, how it works, the efficiency, and what to be aware of when selecting and installing a heat pump in different regions, climate zones and countries.

A heat pump is a versatile heating and cooling system that operates by transferring heat from one location to another. Unlike traditional heating methods that generate heat through combustion, heat pumps harness the ambient heat from the environment, making them an energy-efficient and environmentally friendly solution.

From the European perspective, Morten points to the importance of district heating and individual heat pumps as viable alternatives to fossil fuel-based heating systems. Kitchen suggests that in North America heat pumps play a crucial role in regions lacking natural gas infrastructure, leveraging abundant electricity sources for efficient heating solutions.

Kitchen notes that heat pumps offer a more efficient alternative to traditional heating methods, delivering more heat output than the electricity input. Skovrup agrees, noting that coefficient of performance (COP) quantifies this efficiency, with higher COP values indicating greater energy savings.

To an audience question CO2 heat pumps’ energy consumption, Skovrup clarified that CO2 serves as an efficient carrier of heat, allowing for better efficiencies compared to standard refrigerants. COP is a key metric for assessing efficiency, with higher COP values indicating greater energy savings. CO2 heat pumps reduce carbon footprint as a more sustainable alternative to direct electric heating systems, reducing it by a factor of three or more. This required consideration of factors such as heat source temperature and refrigerant selection when evaluating CO2 heat pump performance.

There are regional differences in heating requirements which impact on heat pump performance. In temperate climates, where winters are mild, heat pumps can efficiently provide both heating and cooling using a simple reversing refrigerant cycle. However, in colder regions where temperatures plummet below freezing, supplemental heating may be necessary to meet heating demands effectively.

Responding to queries about the cost efficiency of CO2 heat pumps compared to electric heaters, Skovrup emphasises the significant energy savings achieved with heat pump installations. By reducing electricity consumption and leveraging renewable heat sources, CO2 heat pumps offer a compelling long-term investment. The payback period depends on factors such as upfront installation costs, system efficiency and regional utility rates.

Proper installation and maintenance is key for maximising the efficiency and lifespan of CO2 heat pump systems. Poorly installed units or inadequate airflow can undermine energy efficiency and lead to early system failure. Regular maintenance checks ensure optimal performance and minimise the risk of costly repairs down the line.

Addressing concerns about intermittent power supply, panellists highlighted the importance of electrical stability for CO2 heat pump operation. Voltage fluctuations and grid instability can affect compressor performance and system reliability. However, the thermal inertia of water-based heating systems can provide some buffering against intermittent power disruptions, offering a potential advantage in managing peak electricity demand.

The panellists unanimously agree that natural refrigerants will dominate the market for heat pumps in the foreseeable future. With an emphasis on efficiency, availability and environmental sustainability, natural refrigerants such as propane, ammonia and CO2 offer significant advantages over synthetic alternatives. Though propane is prevalent in household heat pump applications, industrial heat pumps often utilise a combination of ammonia and CO2 for optimal performance.

The superior efficiency and cost-effectiveness of natural refrigerants make them the preferred choice for most installations, offering the best balance of performance, affordability and environmental impact.

Responding to inquiries about the influence of electricity prices on heat pump investment, Kitchen emphasises the importance of cost comparisons with alternative heating methods. While heat pumps offer significant energy savings compared to electric resistance heating, the payback period may vary depending on regional utility rates and energy mix. Political decisions and geopolitical factors can also influence energy prices and availability, adding complexity to investment calculations.

A heat pump in a residential environment.

A heat pump in a residential environment. Freepik

Technical considerations

The panellists explored the differences between heat pump evaporators and those in traditional air-conditioning systems. While the basic principles remain similar, variations in system design, heat source and application can impact evaporator configurations. Saar lauds the adaptability of heat pump systems to diverse heat sources and emphasises the importance of efficient heat transfer for optimal performance.

Skovrup cautions for the need to adopt seasonal COP calculations which accommodate various operating conditions and load scenarios. This approach offers users a more accurate assessment of a heat pump’s efficiency and performance over time, promoting transparency and informed decision-making.

Of importance is system design, installation and maintenance in ensuring optimal performance and longevity. For instance, Kitchen emphasises the impact of operating conditions on heat pump efficiency, highlighting the role of variable speed compressors in mitigating inrush currents and reducing strain on electrical infrastructure.

They anticipate continued advancements in heat pump technology, with a focus on improving efficiency, reliability and safety. Variable speed compressors emerge as a key solution for optimising energy consumption and reducing demand on electrical infrastructure. As the industry evolves, ongoing collaboration between manufacturers, regulators and service professionals will be essential in addressing emerging challenges and maximising the potential of heat pump technology.

In terms of integrating heat pump systems with other heating solutions, such as oil-based systems, in commercial buildings this can provide both heating and cooling functions efficiently throughout the year. Heat pump technology is sufficiently flexible and versatile to meet diverse heating and cooling requirements in different climates and building types.

The importance of dehumidification in commercial buildings is noted, particularly with the increasing focus on indoor air quality and ventilation standards. The panellists explain how heat pump systems can be utilised for dedicated dehumidification processes, leveraging the heat rejection from the system to sensibly reheat the air, thereby maintaining comfort conditions while minimising energy consumption. This integrated approach to moisture control highlights the potential for heat pump systems to enhance indoor comfort and energy efficiency in various applications.

The concept of heat recovery can be expanded to include waste heat from refrigeration systems, such as supermarket refrigeration units, being captured and utilised for other purposes, thereby maximising energy efficiency and reducing overall energy consumption.

The panellists offer practical advice on mitigating noise issues associated with heat pump systems, with emphasis on the importance of identifying the root cause of the noise, which could range from imbalanced fans to vibration-induced disturbances. They caution that if the noise is inherent to the design of the unit and cannot be resolved through simple adjustments, drastic measures like soundproof enclosures may not be feasible or effective.

Key points:

Identify the source of noise: It’s crucial to investigate whether the noise is caused by mechanical issues such as imbalanced fans or vibrations. Addressing these issues may help reduce noise levels.

Consider design limitations: If the noise is inherent to the design of the unit and cannot be easily resolved, it may be challenging to achieve significant noise reduction without extensive modifications.

Avoid drastic measures: While solutions like soundproof enclosures may seem appealing, they can be complex and costly to implement. It’s essential to assess the feasibility and effectiveness of such measures before proceeding.

Seek professional assistance: If noise issues persist despite troubleshooting efforts, seeking assistance from qualified HVAC technicians or manufacturers may be necessary to explore potential solutions.

By taking a systematic approach to diagnosing and addressing noise issues, property owners can work towards achieving a quieter and more comfortable environment while maximising the performance of their heat pump systems.

Reference

How much do you know about heat pumps?

The following is a transcript of a webinar hosted by Matteo Valerin, national sales manager of CAREL Nordic on 30 January 2024.

Heat pumps are becoming increasingly popular in the HVAC industry due to their efficiency and versatility. In this webinar two experts discussed the intricacies of heat pumps, shedding light on key trends and regulations shaping the market:

Miriam Solana Ciprés from CAREL’s Knowledge Centre, responsible for following regulations and trends in HVAC

Matteo Galenda, application specialist HVAC Residential

The session discussed CAREL’s latest white paper on heat pumps. With the imperative to combat climate change and meet the goals outlined in the Paris Agreement, heat pumps emerge as a key solution to reduce CO2 emissions. Ciprés noted how heat pumps offer a sustainable alternative to fossil fuel boilers, potentially slashing global CO2 emissions by a significant margin.

Despite their potential, heat pumps currently constitute only a fraction of the global HVAC market (albeit growing). Valerin shared insights from the International Energy Agency, indicating that merely 10% of buildings worldwide are equipped with heat pumps. To achieve broader adoption and reach the ambitious target of 20% penetration by 2030, concerted efforts are required, including substantial investments and overcoming various challenges.

Regarding the classification of heat pumps based on their external exchanges, there are three primary types: air source, water source and ground source. Each type harnesses renewable energy, contributing to decarbonisation efforts. While air source heat pumps offer simplicity and lower installation costs, their performance is subject to fluctuations based on outside temperatures. Conversely, water source heat pumps provide consistent performance but require careful consideration of water flow and characteristics. Ground source heat pumps offer stability throughout the year but entail higher installation costs and complexities.

Each heat pump type has advantages and disadvantages. Air source heat pumps offer ease of installation but are susceptible to performance fluctuations and ice formation. Water source heat pumps deliver consistent performance but demand meticulous planning and may incur higher installation costs. Ground source heat pumps provide year-round stability but come with significant upfront investment and implementation challenges.

Navigating safety standards and chemical substances in heat pumps

Ciprés noted the growing importance of adhering to safety standards, particularly in light of the phase-down of fluorinated refrigerants mandated by the Kigali Amendment to the Montreal Protocol. This phase-down necessitates the use of low Global Warming Potential (GWP) refrigerants, many of which are flammable, emphasising the significance of compliance with safety standards such as ISO 60335-2-40.

Attendees learned about the evolution of safety standards, with ISO 60335-2-40:2022 continually updated to accommodate advancements in technology and address safety concerns associated with flammable refrigerants. Notably, the standard was revised in 2018 to include enhanced safety measures for systems utilising hydrocarbon refrigerants. In 2022, further updates were made at an international level, allowing for increased refrigerant quantities under specific safety protocols, including mechanical ventilation and other methods.

A critical aspect of safety standards involves understanding refrigerant charge limits, particularly concerning flammable refrigerants like propane. The maximum refrigerant charge for propane systems employing mechanical ventilation, emphasised Galenda, is capped at 5kg to mitigate potential hazards.

Regarding internal distribution systems within heat pumps, including air-to-air and water-to-water configurations, the typical temperature profiles for various distribution systems with air distribution systems deliver temperatures ranging from 35–40°C in heating mode and water distribution systems. These exhibit varying temperature ranges depending on the type of radiator or fan coil employed.

The two speakers addressed environmental concerns related to chemical substances used in heat pumps, particularly per- and polyfluoroalkyl substances (PFAS). Ciprés noted that the potential environmental and health risks associated with PFAS had prompted regulatory action in the European Union and other jurisdictions to restrict their use.
Close up of a heat pump outside a home.

Close up of a heat pump outside a home. Freepik

Exploring market trends and refrigeration components

Air-to-air heat pumps dominate the global market, constituting approximately 80% of installed units worldwide. However, there has been a notable shift in recent years, with air-to-water heat pumps emerging as the predominant choice in certain regions, particularly in Europe. Insights from the European Heat Pump Association highlighted this evolving trend, underscoring the importance of monitoring market dynamics to anticipate future developments.

Galenda provided a detailed overview of key refrigeration components, essential for the functionality of heat pump systems: condensers, expansion valves, compressors and four-way valves, essential in facilitating heat transfer and refrigerant circulation. Electronic controllers are vital in regulating system operations, alongside advancements such as DC compressors with permanent magnets for enhanced efficiency. This was followed by a Q&A.

Question: ‘How do changes in F-Gas regulations affect the heat pump market?’

Answer: The changes in F-Gas regulations, particularly the latest revision, will indeed have a significant impact on the heat pump market. Here’s how:

The revised regulations include a strong phasedown of fluorinated refrigerants, aiming to reduce their usage over time. This phasedown will directly impact the availability and usage of certain refrigerants commonly used in heat pumps.

For the first time, specific bans on certain types of heat pumps are being introduced. These bans vary based on the type of heat pump, whether it’s a monobloc or split system, and the nominal capacities. These bans are set to come into effect in the near future, with different timelines for implementation depending on the type and capacity of the heat pump.

The regulations also set limits on the GWP of refrigerants that can be used in heat pumps. This means that heat pump manufacturers will need to ensure that the refrigerants they use meet these GWP limits, which may require transitioning to alternative refrigerants with lower GWPs.

Some fluorinated gases will be completely banned under the revised regulations. This adds urgency for manufacturers to transition away from these banned refrigerants and adopt alternatives that comply with the new regulations.

While these regulatory changes present challenges for the heat pump market, such as the need for redesigning systems and transitioning to new refrigerants, they also create opportunities for innovation and market growth. Manufacturers will need to adapt to these changes by developing more sustainable and environmentally friendly heat pump solutions.

Overall, the revised F-Gas regulations signal a significant shift in the heat pump market towards greater sustainability and environmental responsibility. Manufacturers, policymakers and stakeholders will need to work together to navigate these changes and ensure a smooth transition to more eco-friendly heating and cooling solutions.

Question: Does using an electronic expansion valve instead of a thermostatic valve influence compressor consumption?

Answer: The main difference lies in the fact that the thermostatic valve is a mechanical device that operates using a bulb connected to the outlet to ensure correct function. On the other hand, a standard electronic expansion valve is controlled based on electrical signals from the controller, which then act on the stator. The stator, usually a stepper motor, changes the position of the internal device.

There are benefits of using the electronic expansion valve. Firstly, it ensures precise and stable superheat control, with faster regulation and a wide working range, making it ideal for DC compressors. It allows for accurate charging of the refrigerant, eliminating the need for frequent recalibration required for thermostatic valves. Another advantage is the perfect closure of the orifice, minimising the risk of liquid entering the compressor. In case of unit shutdown, the valve blocks the refrigerant, ensuring proper compressor restart. Additionally, in case of malfunction, the system can send an alarm to the controller, alerting the customer.

Several studies, including ones conducted by laboratories, have demonstrated the benefits of electronic expansion valves over thermostatic valves. Laboratory tests have shown a 50% reduction in power consumption during off cycles, attributed to faster attainment of setpoints and quicker valve closure. On-site testing revealed savings ranging from 15%–35%, depending on operating conditions, with some studies reporting even higher benefits, up to 40%. In summary, using electronic expansion valves guarantees better performance and energy efficiency.

Question: What sizing methodologies for heat pumps exist compared to boilers?

Answer: Heating systems must compensate for losses in building transmission and ventilation to ensure comfort throughout the year. However, the methodologies differ between boilers and heat pumps. Boilers typically handle instantaneous hot water production, requiring higher thermal power compared to heat pumps, which often utilise a domestic hot water tank. Sizing for heat pumps considers factors such as geographical location and internal distribution temperature to achieve the right balance between heating demand and capacity.

Question: What are the key market trends?

Answer: Detailed information can be found in CAREL’s white paper, but to summarise, digitalisation is a significant trend, with demand response strategies and optimisation of components playing crucial roles. Heat pumps are being researched for expanded temperature ranges, compatibility with alternative refrigerants, and integration into ventilation systems. Other trends include noise reduction, smaller sizes and recyclability in line with circular economy policies and green objectives.

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