11 August 2025
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Tom Merton, Technical Manager, Armacell® UK, looks at the why one of the best ways to maximise heat pump efficiency is to adequately insulate external pipework.
Heat pumps are often exposed to moisture and limiting space constraints as well as having to operate across wide temperature ranges. These conditions can severely impact the entire heating system, which is why efficient and robust insulation is essential.
To help specifiers and contractors protect equipment against these environments, the industry has responded with insulation solutions that provide a reliable shield against external moisture and temperature shifts, while improving acoustic performance and delivering the flexibility needed to fit installations into complex dimensions.
In these scenarios, the correct installation technique, combined with high-quality insulation materials, can also significantly reduce maintenance costs.
Types of insulation for heat pump pipework
When it comes to optimising the efficiency of a heat pump system, selecting the right insulation for outdoor pipework is crucial. The insulation not only needs to protect the pipes from environmental factors but also ensure that the system operates at peak performance. The options are; pre-insulated pipework or, where pipework is already installed, retrofitting with a UV resistance material.
Insulation plays a vital role in maintaining the temperature of the fluid within the pipes in the critical section between the property and the outdoor unit. This is particularly important with heat pumps because system efficiency relies on transferring heat from one location to another. Without adequate insulation, the overall system efficiency can be significantly compromised, leading to increased energy consumption and higher operational costs. Conversely, well-insulated pipes minimise heat loss, allowing the heat pump to operate more efficiently. This reduced energy consumption translates to lower utility bills, making insulation a worthwhile investment. Correctly specified insulation – such as an elastomeric closed cell material - also protects pipes from extreme temperatures and environmental damage, prolonging their lifespan.
When it comes to selecting insulation for outdoor heat pump pipework it depends on whether it is for a new installation of retrofit of existing pipework:
New installations: Pre-insulated pipes, are elastomer insulation materials designed specifically for new heat pump installations. These kinds of pipes come with built-in insulation, which simplifies installation and, because it is applied in a quality controlled production environment, ensures consistent thermal performance.
Being pre-insulated also means the pipes are ready for immediate use, reducing installation time and labour costs. When choosing pre-insulated pipes it is important to verify that they are resistant to UV rays and other environmental factors such as moisture, which makes them suitable for outdoor use.
Check that the pre-insulated pipe lengths offered are suited for space-saving installations so you have the option of installing the heat pump close to the house wall, which is necessary if it is not possible to lay the pipework underground. We offer sets in 2,4,6,8 metre pre-insulated pipes, with two individual pipes (flow and return f low) in one box. Alternatively, there is a 25m coil option. All in DN25 and DN32.
If you choose pre-insulated corrugated pipes it will provide you with good bending capacity/ flexibility, making it possible to implement individual solutions for the choice of installation location of the heat pump’s outdoor unit. For quicker installation, check they are supplied with appropriate quick couplings.
Existing pipework: For existing heat pump pipework that requires insulation, UV-resistant options can be used. These flexible elastomer insulation materials have exceptional resistance to UV radiation and high temperatures. In additional, the closed cell structure and low thermal conductivity of these materials keeps water vapour from diffusing in and reduce energy losses, protecting and optimising the efficiency and life time expectancy of the installation.
While remaining flexible at application temperatures of up to 150°C, being dust and fibre free and easy to install without special tools, makes it an easy installation. We developed our product so that is doesn’t need additional jacketing, does not degrade in sunlight and withstands incidental oil contact.
Due to the thermal properties of these kinds of elastomer insulation materials, the heat flow from the air source unit to inside the building is kept at its utmost minimum. The evenly spread, homogenous and long term stable closed cell structure prevents convection heat loss, ensuring very low thermal conductivity of the insulation material.
Retrofit is an approach that is often preferred with contractors and their customers because it can be more economical than replacing the entire system.
Factors to consider when choosing insulation
Whether for a new installation of upgrading an existing, selecting the right insulation involves considering several factors to ensure optimal performance and longevity:
Pipe size and type: The diameter and material of the pipes will influence the type of insulation required. It is necessary to measure the outer diameter of the pipes to be retrofitted accurately to ensure a proper fit.
Environmental conditions: Consider the climate and environmental conditions where the pipes will be installed. Areas with extreme temperatures or high UV exposure may require more robust insulation solutions. If this is the case, an elastomeric insulation that has a high UV-resistance is best suited.
Installation location: The location of the pipes — whether they are buried underground, exposed to the elements, or situated in a sheltered area — will affect the choice of insulation. For example, underground pipes in a shallow trench may require more insulation to prevent freezing.
Resistance to impact damage: Where there is potential for mechanical impact on the pipework, there are pre-coated solutions available. These also provide wash-down waterproofing, whilst being easy to clean and UV resistance for external use. It requires no additional painting or covering and can be used on underground pipework, including main cold water and ground source heat pumps.
Fire safety: Flexible elastomeric foams with improved fire-retardant properties are available. These have low smoke generation and can be specified with our Arma-Chek® Wrap, a self-welding material with high mechanical resistance that is 100 percent recyclable and free of halogens, silicone and solvents. It is simply wound around the insulated pipe with an overlap of 20 mm. The self welding material bonds to the surface of the insulation without any further action. It does not vulcanize immediately, but the installation can still be adjusted within 10 to 20 minutes after application.
Installation best practices: Proper installation of insulation is crucial for achieving the desired performance. It should fit snugly around the pipes to prevent gaps that could lead to heat loss and one of the best ways of achieving this is the use appropriate adhesives or tapes to secure the insulation in place. Special attention should be given to joints and connections, as these areas are prone to heat loss. Use UV-resistant tape to seal any gaps and ensure a continuous layer of insulation. Moisture can also compromise insulation performance and so it is important to ensure that the insulation is installed in a way that prevents water accumulation, particularly in outdoor settings.
Optimising efficiency: Choosing the right insulation for outdoor heat pump pipework is essential for maximising efficiency and reducing energy costs. Whether opting for pre-insulated pipes or retrofitting existing pipes, both with UV-resistant elastomeric insulation, understanding the specific needs of the system will guide your decision. By considering factors such as pipe size, environmental conditions and installation best practices, you can ensure that your customers’ heat pumps operate effectively for years to come.
In summary, investing in quality elastomeric insulation not only enhances the performance of the heat pump but also contributes to long-term savings and environmental sustainability.
www.armacell.com
