Restore circulation and efficiency to central heating systems suffering from sludge build-up. Sentinel X400 is a powerful, non-acidic cleaner designed to lift and disperse corrosion debris and sludge from older systems.

Its highly effective formula works to eliminate cold spots in radiators and restore proper heat distribution, preparing the system for the addition of an inhibitor. This 250ml Rapid-Dose canister is designed for fast and simple application, making system maintenance easier than ever.

• Removes sludge – lifts and disperses built-up corrosion deposits.
• Restores efficiency – helps to eliminate radiator cold spots and improve circulation.
• For older systems – specifically formulated to clean systems more than six months old.
• Rapid-Dose – fast and simple application for easy system maintenance.

Delivery (UK mainland only)

 

Next Day: £5, or FREE over £40

- Order by 9pm Mon-Thu: next working day

- Order Fri to 5pm Sun: Monday

- Order after 5pm Sun: Tuesday

 

Pre-12pm: £10

- Same cut-offs as Next Day above

 

Saturday & Sunday: £10, or £5 over £40, or FREE over £75

- Saturday: order by 6pm Fri

- Sunday: order by 4pm Sat

 

Heavy items (over 30kg)

- Mon-Fri only. Order by 6pm and allow up to two working days

- Order after 6pm Thu: arrives after the weekend

 

Supplier items

- Sent directly by the supplier, so timings vary. Lead times appear on the product page in working days (Mon-Fri)

 

More about delivery 

Next Business Day Collection (eligible items)

- Order by 9pm Mon-Thu: collect next day

- Order after 9pm Thu to 5pm Sun: collect Monday

- Heavy items (over 30kg): allow up to two working days

 

Opening hours

- Weekdays vary by branch: open 6:30am-7am, close 6pm-8pm

- Saturday: 7am-6pm

- Sunday: 9am-4pm

 

Check your local store's hours and that it's open before visiting. Please wait for our text or email before collecting.

 

Holding your order
We'll hold it for 14 days, then automatically refund your original payment method.