Central Heating Treatments

Protect and maintain your heating system with our range of central heating treatments from trusted brands including Fernox and LavaTherm. Our collection covers everything you need to keep your boiler, radiators, and pipework running efficiently — helping prevent corrosion, sludge build-up, and costly breakdowns.

Limetron Water Conditioner 15mm Whole Home Limescale Reducer
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Limetron Water Conditioner 15mm Whole Home Limescale Reducer

£197.95

LavaTherm 15mm Electrolytic Scale Reducer Inline Limescale Prevention Device
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LavaTherm 15mm Electrolytic Scale Reducer Inline Limescale Prevention Device

£9.99

Sentinel X100 Inhibitor 500ml Super Concentrate

Sentinel X100 Inhibitor 500ml Super Concentrate

£9.99

Fernox F1 Protector Express 400ml 62418

Fernox F1 Protector Express 400ml 62418

£24.29

H&V 22mm Electrolytic Scale Reducer

H&V 22mm Electrolytic Scale Reducer

£19.99

Fernox TF1 Complete System Filter 22mm Magnetic Boiler Filter for Central Heating Systems

Fernox TF1 Complete System Filter 22mm Magnetic Boiler Filter for Central Heating Systems

£94.99

LavaTherm Boiler Care Pack 22mm Magnetic Filter & 500ml Central Heating Inhibitor (Part L Compliant)

LavaTherm Boiler Care Pack 22mm Magnetic Filter & 500ml Central Heating Inhibitor (Part L Compliant)

£49.99

LavaTherm 22mm Magnetic Filter Central Heating Sludge Remover - Boiler Protection

LavaTherm 22mm Magnetic Filter Central Heating Sludge Remover - Boiler Protection

£38.99

£44.99

Sentinel Central Heating Radiator Leak Sealer 1L

Sentinel Central Heating Radiator Leak Sealer 1L

£14.99

H&V 15mm Electrolytic Scale Reducer Inline Limescale Prevention Device

H&V 15mm Electrolytic Scale Reducer Inline Limescale Prevention Device

£12.99

Fernox TF1 Sigma UB Filter 22mm

Fernox TF1 Sigma UB Filter 22mm

£69.99

Calmag Magnetic Boiler Filter and Chemical 22mm
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Calmag Magnetic Boiler Filter and Chemical 22mm

£49.99

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Central Heating Inhibitors, Cleaners & Filters

Central heating inhibitor from Fernox, Sentinel and LavaTherm, starting at £7.99. Dosage is not the same across brands, so check before you buy: a 500ml bottle of Fernox F1 treats up to 130 litres or around 16 radiators, while 500ml of Sentinel X100 Super Concentrate or LavaTherm treats up to 100 litres, or roughly 10 radiators. All of them are safe with aluminium heat exchangers, and Fernox F1 is approved by NSF, KIWA and Belgaqua.

Beyond inhibitor, the range covers central heating cleaner in Fernox F8 and Sentinel X800, leak sealers in both liquid and 30-second aerosol form, Fernox F7 biocide for underfloor and low-temperature circuits, 22mm magnetic filters from Fernox, BoilerMag, Calmag and LavaTherm, and electrolytic and catalytic scale reducers for the cold mains. BS 7593:2019 best practice is to check inhibitor levels annually and re-dose every five years. Trade prices, same-day dispatch on orders before 1pm.

Not sure what your system needs, or how much of it? Tell us the radiator count and we’ll work out the dose. Get in touch and we’ll help you find the right part.

Central Heating Treatments – FAQs

How much central heating inhibitor do I need?
It depends on the brand, not just the bottle size. One 500ml bottle of Fernox F1 treats systems up to 130 litres – around 16 radiators, or 250m² of underfloor heating. 500ml of Sentinel X100 Super Concentrate or LavaTherm Super Concentrate treats up to 100 litres, around 10 radiators. Always dose to the bottle, not to a rule of thumb.
How often should central heating inhibitor be replaced?
BS 7593:2019 best practice is to check inhibitor levels annually as part of the boiler service, and re-dose every five years.
What is the difference between a central heating cleaner and an inhibitor?
A cleaner such as Fernox F8 or Sentinel X800 breaks down existing sludge, magnetite and scale, and is then flushed out. An inhibitor such as F1 or X100 stays in the system to stop corrosion and scale coming back. Cleaning without then protecting means the sludge returns.
Do I need to flush the system after using a central heating cleaner?
Yes. Both Fernox F8 and Sentinel X800 are drained and flushed out after circulating, and the system is then refilled with inhibitor for ongoing protection.
Are central heating treatments safe with an aluminium heat exchanger?
Yes. Fernox F1, F7 and F8 all state compatibility with every metal used in central heating including aluminium, and Sentinel X100 and X800 cover aluminium, copper, steel and mixed-metal systems.
Will a central heating leak sealer fix my leak?
Only a small one. Sentinel’s leak sealer targets pinhole leaks and weeping joints and forms a seal normally within 24 hours. Fernox F4 Express doses in 30 seconds without draining the system, but is explicitly not suitable for major leaks or burst pipes, and should not be used in a heavily sludged system. Treat it as a fix for pressure loss you cannot trace, not a substitute for a repair.
Can I add inhibitor without draining the system?
Yes. Fernox F1 Protector Express is an aerosol that doses in around 30 seconds through a radiator, filling loop or TF1 filter. If you have a magnetic filter fitted, its access point usually doubles as a dosing port.
Do I need a biocide as well as an inhibitor?
On underfloor heating and other low-temperature or intermittently used circuits, yes – those conditions suit bacterial growth that an inhibitor alone will not address. Fernox F7 is designed for exactly that and is used alongside an inhibitor, not instead of one. One 200ml bottle treats up to 150 litres.
What size magnetic filter do I need, and where does it go?
Fit it on the return, as close to the boiler as you can get it – that way it catches magnetite and debris on the way back, before it reaches the heat exchanger. Domestic boiler flow and return pipework is 22mm, or 28mm on larger systems, so that is the size the filter needs to match. 15mm is only used on the legs out to individual radiators, which is too far downstream to protect the boiler. All our inline filters are 22mm to suit standard domestic pipework. The Fernox TF1 Sigma UB is the exception to check – it is designed for specific Ideal and Vokera boilers rather than being a universal fit.