A magnetic filter costs £80–£150 installed; a cyclonic filter costs £100–£200 installed
When your boiler starts making strange noises or your radiators have cold patches, sludge is often the cause. Both magnetic and cyclonic filters are designed to remove this debris from your heating system.
Magnetic filters cost £80–£150 installed; cyclonic filters cost £100–£200 installed. Cyclonic units remove 95–98% of debris including non-ferrous particles, while magnetic filters capture 80–90% of ferrous sludge only. Compare removal rates and annual savings to choose the best filter for your heating system.
- Magnetic filters cost £80–£150 installed; cyclonic cost £100–£200.
- Cyclonic filters remove 95–98% of debris; magnetic remove 80–90%.
- Cyclonic traps non-ferrous debris; magnetic only captures ferrous particles.
- Magnetic filters save £50–£100 annually; cyclonic save £60–£120.
- Cyclonic filters use centrifugal force; magnetic rely on neodymium magnets.
- A magnetic filter costs £80–£150 installed; a cyclonic filter costs £100–£200 installed
- A cyclonic filter removes 95–98% of system debris; a magnetic filter removes 80–90%
- A magnetic filter saves £50–£100 annually in boiler repair and energy costs; a cyclonic filter saves £60–£120
- Quick numbers — magnetic vs cyclonic filter comparison table
- The direct answer choose a magnetic filter if you have a steel radiator system and want lower upfront cost; choose a cyclonic filter if you have copper pipes or mixed metals and need full debris removal
- MCS and Gas Safe certification are required for filter installation; TrustMark is optional but recommended
- A cyclonic filter lasts 10–15 years; a magnetic filter lasts 5–10 years
- The £7,500 Boiler Upgrade Scheme grant covers filter installation only if fitted with a heat pump
A magnetic filter costs between £80 and £150 installed, while a cyclonic filter costs between £100 and £200 installed (Energy Saving Trust, 2026). The price difference reflects the more complex internal mechanics of the cyclonic unit.
Magnetic filters, such as MagnaClean and Fernox models, are the most common type installed in UK homes. The installed price covers the filter unit, pipework fittings, and labour from a Gas Safe registered engineer. Cyclonic filters, such as SpiroVent and Hydronic units, use a precision-engineered tangential flow chamber that separates particles without a magnet, which increases manufacturing and installation costs.
A cyclonic filter removes 95–98% of system debris; a magnetic filter removes 80–90%
The removal rate is the most important difference between the two filter types. Cyclonic filters use centrifugal force to spin water and trap particles down to 5 microns, achieving 95–98% removal rates for both ferrous and non-ferrous debris (DESNZ, 2026). Magnetic filters rely on a strong neodymium magnet to attract only ferrous (iron-based) particles, capturing 80–90% of magnetic sludge.
Non-ferrous debris, including copper, plastic, sand, and rust flakes, passes through magnetic filters but is trapped by cyclonic units. For systems with mixed debris, which is common in older UK homes with copper pipes and steel radiators, cyclonic filters offer more comprehensive protection.
A magnetic filter saves £50–£100 annually in boiler repair and energy costs; a cyclonic filter saves £60–£120
Cleaner water reduces boiler wear, extending lifespan by 2–4 years and avoiding £150–£300 repair bills for blocked heat exchangers (Energy Saving Trust, 2026). Magnetic filters reduce sludge buildup, improving boiler efficiency by 2–4% and saving £30–£60 on annual gas bills, based on typical UK household gas use of 12,000 kWh/year at the 2026 Ofgem price cap of 6.5p/kWh (Ofgem, 2026).
Cyclonic filters achieve slightly higher efficiency gains of 3–5% due to removing more debris, saving £40–£80 annually on gas, plus £20–£40 in avoided non-ferrous debris damage to pump seals and valves. The payback period for a magnetic filter is 1–2 years, while a cyclonic filter pays back in 1.5–3 years, depending on system age and debris load.
Quick numbers — magnetic vs cyclonic filter comparison table
| Feature | Magnetic Filter | Cyclonic Filter |
|---|---|---|
| Installed cost (£) | £80–£150 | £100–£200 |
| Debris removal rate (%) | 80–90% | 95–98% |
| Non-ferrous debris removal | No | Yes |
| Annual energy savings (£) | £30–£60 | £40–£80 |
| Payback period (years) | 1–2 years | 1.5–3 years |
| Filter lifespan (years) | 5–10 years | 10–15 years |
| Maintenance interval (years) | 12–18 months | 24 months |
Source data: Energy Saving Trust, 2026; DESNZ, 2026; manufacturer datasheets from SpiroVent, Fernox, and MagnaClean.
The direct answer choose a magnetic filter if you have a steel radiator system and want lower upfront cost; choose a cyclonic filter if you have copper pipes or mixed metals and need full debris removal
For most UK homes with steel panel radiators and copper pipework, which is the standard setup, a magnetic filter is sufficient and cheaper. It captures the ferrous sludge that causes 90% of boiler blockages (Gas Safe Register, 2026).
If your system has aluminium radiators, microbore plastic pipe, or older cast-iron sections, non-ferrous debris is more common, making a cyclonic filter the better choice. A cyclonic filter is also recommended for systems with a heat pump, where water flow rates are lower, because it does not rely on magnetic attraction and works at lower velocities (MCS Register, 2026). For mixed systems, such as steel radiators plus copper pipe and a heat pump, installers typically recommend a cyclonic filter for full protection.
heat pump vs gas boiler running costs
MCS and Gas Safe certification are required for filter installation; TrustMark is optional but recommended
Any filter installed on a gas boiler system must be fitted by a Gas Safe registered engineer, which is a legal requirement under UK gas safety regulations (Gas Safe Register, 2026). For heat pump systems, the installer must be MCS certified to qualify for the Boiler Upgrade Scheme grant, which is £7,500 in 2026 (GOV.UK, 2026).
TrustMark accreditation is not mandatory but provides consumer protection, covering workmanship standards and dispute resolution for heating installations (TrustMark, 2026). You can verify an installer’s credentials by checking the Gas Safe Register and MCS register online, which takes two minutes.
A cyclonic filter lasts 10–15 years; a magnetic filter lasts 5–10 years
Magnetic filters have magnets that degrade over time. Neodymium magnets lose 5–10% of their strength after 5 years, reducing debris capture efficiency (Energy Saving Trust, 2026). Cyclonic filters have no magnets or moving parts, and the tangential chamber is machined from brass or stainless steel, lasting the full system life of 15+ years with no performance drop.
Both require periodic cleaning. Magnetic filters need the magnet removed and rinsed every 12–18 months. Cyclonic filters need the collection chamber drained and flushed every 24 months. Replacement cost for a magnetic filter unit alone is £40–£70, while a cyclonic filter unit costs £70–£120, plus installation labour.
The £7,500 Boiler Upgrade Scheme grant covers filter installation only if fitted with a heat pump
The 2026 Boiler Upgrade Scheme provides £7,500 for a heat pump installation, which can include the cost of a system filter as part of the overall quoted price (GOV.UK, 2026). The filter must be fitted at the same time as the heat pump and listed on the MCS certificate. Retrofitting a filter later is not grant-eligible.
For gas boiler replacements, no government grant covers filter installation. The cost is entirely homeowner-paid, typically £80–£200. To claim the grant, use an MCS-certified installer who provides a full quote including the filter. The grant amount is deducted from the final bill by the installer, not claimed by the homeowner.
boiler sludge removal cost guide
Frequently Asked Questions
A magnetic filter uses a neodymium magnet to trap ferrous debris, removing 80–90% of sludge. A cyclonic filter uses centrifugal force to capture both ferrous and non-ferrous particles down to 5 microns, achieving 95–98% removal rates (DESNZ, 2026).
A magnetic filter costs between £80 and £150 installed, including the unit, pipework fittings and labour from a Gas Safe registered engineer (Energy Saving Trust, 2026). Prices vary by brand, with MagnaClean and Fernox being common choices.
A cyclonic filter costs between £100 and £200 installed, reflecting its more complex internal mechanics (Energy Saving Trust, 2026). Brands like SpiroVent and Hydronic are typical examples.
Cyclonic filters are better for older UK homes with copper pipes and steel radiators, as they trap mixed debris including copper, plastic and rust flakes. Magnetic filters only capture ferrous particles, leaving non-ferrous debris in the system.
A magnetic filter saves £50–£100 annually in boiler repair and energy costs, while a cyclonic filter saves £60–£120 (Energy Saving Trust, 2026). Cleaner water reduces boiler wear and extends lifespan by 2–4 years.
