Heat pumps are among the most technologically advanced heating sources – we all know that. However, their efficiency and trouble-free operation largely depend on the quality of the hydraulic system. In terms of sensitivity and delicacy, they are incomparable to old boilers which, as the saying goes, were “indestructible.” Reliability and relatively low energy consumption require a high-quality heating system – and as we know, this condition is not always met. Heat pumps, especially in times of subsidies, are often installed in older buildings.
One of the components increasingly appearing in such systems is a magnetic filter for a heat pump – precisely to protect the heat pump from the impact of an old heating system. Is it really worth using, and what benefits can it bring?
A magnetic filter is a small device installed in a heating system, designed to capture ferromagnetic impurities circulating in the system. “Ferromagnetic” simply means metallic debris – rust particles from the installation, etc. These are mainly magnetite particles – a corrosion product of steel components such as pipes, manifolds, hydraulic separators, or heat exchangers. Sometimes even time-degraded pipes or radiators.
In heat pump installations, the magnetic filter serves a protective function, preventing contaminants from reaching key components of the unit – in this case the heat pump – but in practice also protecting other central heating components.
The operating principle of a magnetic filter is simple but highly effective. Heating water flowing through the filter passes by a strong magnet that attracts metal particles and ferromagnetic sludge. These impurities are retained inside the filter housing and do not continue circulating in the system.
As a result:
Does the last point also apply to a heat pump? Absolutely. In a clean system like this, the heat pump achieves a higher COP, meaning it operates more efficiently and economically, with lower electricity consumption.
It is worth noting that alongside the term “magnetic filter,” another name is used interchangeably: dirt separator for a heat pump. Why is it important?
Because heat pumps have narrow flow channels in their heat exchangers, which are much more sensitive to contamination than those in traditional boilers. Even a small amount of deposits can lead to:
The use of a magnetic filter limits these risks and stabilizes the operation of the entire system.
This description can be slightly modified – and it turns out that other modern heating devices are just as sensitive as heat pumps. All boilers equipped with electronics, sensors, and heat exchangers fall into this category. Therefore, it is worth using dirt separators also with gas boilers or modern pellet boilers. Unless we are dealing with completely new closed-loop installations – although studies show that even in such systems, installing magnetic filters is beneficial.
Naturally, there is a difference between a new system and an older, somewhat degraded heating system.
In new systems, the magnetic filter acts preventively, protecting the installation from contaminants formed during operation. It is not always installed, and its absence does not automatically mean increased failure risk for the heat pump. Its function is mainly preventive.
Here the situation is different. One should assume that the system is already somewhat worn and may contain internal impurities, even if it was a closed system. When connecting a heat pump to an existing installation, its use is particularly recommended. Older systems often contain large amounts of deposits that begin circulating intensively once a new heat source is started.
If connecting a heat pump to an open system, direct connection is generally not possible. The heat pump itself must remain in a closed loop. In such cases, a heat exchanger for a heat pump is used to connect the two systems (this refers to an external exchanger, not the condenser). If the open system is contaminated, a dirt separator is also installed to protect the exchanger.
Let’s be honest – open systems are outdated. If you are dealing with one, it usually means the installation is old and not an ideal environment for sensitive devices.
Formally, a magnetic filter is not always required, but from a practical standpoint it is one of the cheapest and most effective protections for the system. Unless the heat pump manufacturer requires a dirt separator to maintain warranty coverage – such cases do occur, and this also applies to some modern boiler manufacturers. Installing a dirt separator with a heat pump usually does not complicate the installation, takes up little space, requires little time, and is one of the simpler hydraulic tasks.
The cost of a magnetic filter is small compared to:
For this reason, many manufacturers and installers treat magnetic separators as a reasonable standard, not an unnecessary add-on.
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