As heat pumps become more commonplace, it is important to understand both the similarities and differences to traditional boiler systems and how to protect heat pumps effectively.
The drive for lower carbon emissions has accelerated the adoption of heat pumps in the UK. Helping to accelerate this is the Future Homes Standard, which has now confirmed that from 2028, the vast majority of homes and buildings will be constructed with low-carbon heating systems. This is a positive step but, with the expected uptake, it is also crucial to understand how to protect these systems for the long term.
To begin with, consider the similarities between gas boilers and heat pump systems. While they produce heat through different processes, heat pumps still rely on the same water-based central heating infrastructure such as pipework, radiators and underfloor heating. As a result, they remain susceptible to issues such as corrosion, limescale build-up, and damage from circulating debris, meaning proper protection is essential to maintain both efficiency and lifespan.
The recommended approach is the same as when dealing with traditional boiler systems: a combination of chemical water treatment and an in-line system filter, along with routine servicing and monitoring of inhibitor levels, as specified in BS 7593:2019. Since June 2022, the requirements of this standard have been incorporated into Part L of the Building Regulations in England.
Using both methods together is the crucial part. A high-quality inhibitor chemically protects the metal surfaces in the system, preventing sludge and limescale formation, while a system filter removes existing contaminants and any debris that may enter the system accidentally.
TEMPERATURE AND FLOW-RATES
However, heat pumps also present their own unique protection challenges that require careful consideration. One of the most significant differences is that most heat pumps operate at much lower flow temperatures, which is advocated by the Building Regulations to reduce the carbon footprint of homes.
Operating at lower temperatures (typically between 35°C and 55°C) increases the risk of microbiological growth. These conditions allow bacteria to thrive, potentially forming biofilms on system surfaces, which can reduce efficiency and accelerate system degradation through Microbiologically Influenced Corrosion (MIC). To mitigate this risk, it is essential to incorporate an effective biocide alongside other chemical treatments, as recommended in BS 7593:2019.
In addition to lower temperatures, heat pumps often run at high flow rates of up to 80 litres/min. This must be considered when selecting a system filter. Filters designed for lower flow systems, or those relying solely on magnets to capture particles, may underperform in these conditions, which will allow contaminants to be washed back into the system. Instead, look to filters that have been specifically engineered for heat pumps and designed to capture debris efficiently
– even at high flow rates. The Fernox Sigma HP Filter, for example, uses its ‘Flow Disruptor’ to create low-flow zones within the filter, while encouraging particles to settle at the base, rather than being returned into circulating system water.
Finally, it’s important to choose a filter that optimises water flow while minimising pressure loss. This ensures the heat pump can operate efficiently and continue to maintain the required Coefficient of Performance (CoP).
As with all heating components, the quality of the products used on heat pump systems is a key consideration. Products from reputable manufacturers should always be used. It is also vital to select a filter that has been rigorously tested to assess its long-term performance and durability.
Despite there being some similarities between traditional systems and those that are incorporating heat pumps, it is important to factor in how they differ to ensure heat pumps, and the wider heating system, are adequately protected in the long term.
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