Sentinel - X100 Inhibitor 1L, Market Leading Heavy Duty Central Heating Inhibitor, Protection Against Corrosion and limescale, ensures Maximum Heating Efficiency and extends System Life, Clear (88000)

The best Inhibitor

I always add sentinel to my Radiators winter time it helps my Heating run well and keep the Radiators clean. I change it every year. So always flush out the Radiators before adding sentinel to your system.if your not sure check before adding.

Why I Bought It I picked up Sentinel X100 because my central heating system shows early signs of scale, boiler noise, and mild corrosion. I wanted a treatment that protects metals (including aluminium), prevents limescale and hydrogen gassing, and maintains efficiency without frequent re-treatments. Setup / First Impressions The 1-litre bottle is easy to dose, with clear instructions. The product is pH neutral, non-toxic and biodegradable, which is reassuring. Packaging is practical; the liquid is clear (slightly tinted), and there’s minimal mess in pouring. I also liked that Sentinel offers a test kit to check inhibitor concentration in the system. Performance / Quality After adding X100 into my already flushed, clean system, I noticed quieter operation (less boiler gurgling), better efficiency — radiators heat evenly and stay warmer with less cycling. The TripleTech™ anti-corrosion technology seems to do its job: no visible scale deposits so far and corrosion activity appears minimal. On the downside: its performance depends on good prior cleaning and flushing — if the system is heavily sludged or scaled, X100 alone won’t reverse all issues. Also, you need to dose correctly (about 1% of system water volume) and occasionally check concentration (especially after draining or refilling). Pros ✔️ Protects against scale, corrosion, boiler noise, hydrogen gas — comprehensive protection for metals including aluminium. ✔️ pH neutral, non-toxic, environmentally better than harsher chemicals. ✔️ Helps maintain system efficiency, extend life of boiler/exchanger. ✔️ Once dosed, it needn’t be replaced unless system is drained. Cons ❌ Needs a clean/flushed system beforehand — otherwise it can’t fix existing scale or heavy sludge. ❌ Correct dosage and periodic concentration checks are necessary; small systems may be sensitive to over/underdosing. Final Verdict If you want long-term protection for your central heating system — especially to reduce corrosion, maintain efficiency, and quiet the system — Sentinel X100 is a solid investment. It works very well under the right conditions (clean system, proper dosing). If your system is old, very dirty, or badly scaled, expect that additional cleaning or even professional descaling may be needed first.

Used this product before but sat and selected all the kit needed for job and delivered next day well packaged

I've been using this inhibitor in our "new" combi boiler since it's installation 7 years ago with good results..so bought this to add some to the central heating after my annual check/cleaning of the magnetic filter..price acceptable & no problems from ordering to delivery in the time slot advised so happy with my purchase...Thank you!!

Good stuff, used for some years.

Rads safe from rust now

I had a crazy situation after my boiler was replaced, at which time the system was dosed with this inhibitor. After a period when things were fine, the system started to gain pressure and the radiators needed vented twice a week to keep the pressure down. Internet research suggested this could be hydrogen gas, formed by the corrosion process in the radiatiors. To satisfy my curiousity I found I was able to ignite the venting gas, confirming the presence of hydrogen and therefore corrosion! After inaction from the installer, I purchased my own Sentinel X100 to add added to the system. It took a couple of weeks to get results but the gasing has stopped. Sadly around about the same time the seal at many of the radiator connections including the blanking plugs and vent plugs has softened and slight leaks have appeared, pressure dropping etc. I wondered if this is a consequence of my actions or just bad luck. Any ideas?