How to Add Corrosion Inhibitor (UK)
Dose Fernox F1 or Sentinel X100 into a UK wet central heating system. TDS test, dosing route and top-up frequency.
FernoxSentinel
Why inhibit
Untreated water at 70 °C oxidises radiator steel — sludge in 2–3 years. Inhibitor to 500 ppm keeps the system clean for 10+ years.
Dosing routes
- Rad bleed injection — Fernox Superconcentrate 265 mL via bleed valve.
- Filling loop — Fernox F1 Express 500 mL cartridge.
- F&E tank — traditional dose into the header tank.
Test
Fernox Test Kit checks concentration annually. Top up whenever system is refilled after work.
Frequently asked questions
- Do combi boilers need inhibitor?
- Yes — condensing boiler HEXs are more sensitive to sludge than old cast-iron units. 500 mL F1 per 100 L system minimum.
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