Product Guides & Information

How to: Clean a Central Heating System

Over time, corrosion can cause sludge build ups inside central heating systems. If not properly treated, this can lead to potential problems and breakdowns. Although commonly cleaned through when first installed removing flux and small copper particles, a heating system's metal components can become corroded over time also causing sludge deposits.

You can typically spot signs of corrosion and sludge either by the boiler growing gradually louder over time, by radiators developing pin holes/having cold areas at the bottom, or by the wearing of pumps and valves. It has also been found that mineral deposits and limescale left by hard water can also lead to system failures.

To prevent system damage, we highly recommend cleaning it through at the first signs of corrosion or build-ups. For this, we'd highly recommend the fantastic Everbuild P11 Central Heating System Cleanser.

The cleanser is effective on plastic, microbore and all types of metal systems as well as being very economical – 1 litre can treat a 100-litre system.

How to use it:
Step 1: Turn off the boiler, mains water supply and drain down the system
Before you start any work, you'll want to make sure that all water is out of the system. To do this first turn off the boiler, mains water and locate the drain valve outlet. Run a hose from the outlet to a suitable drain outside securing it in place with a jubilee clip to minimise the risk of leaks. We'd recommend putting collection dish under the connection just in case. Open the valve to drain the system. Once the system is fully drained, close the valve and remove the hose.

Step 2: Locate the central heating expansion tank and feed 
Next, you'll want to find the central heating feed and expansion tank in order to add the Everbuild P11. Please ensure that you have located the expansion tank and NOT a cold water storage tank.

Step 3: Add Everbuild P11 Central Heating System Cleanser to the expansion tank
Once you've found the expansion tank, simply shake the Everbuild P11 bottle and pour all of it into the tank.

Step 4: Turn on mains water supply, refill the system and restart the boiler
Now we need to refill the system. First turn the main water supply back on. Then locate the filling loop on your boiler (which will normally look like a braided hose), and ensure both valves are open to repressurise the system (check the boilers installation pack for recommended pressure level). Once the correct pressure is achieved, turn the boiler back on.

Step 5: Bleed all radiators in the system
The next step is to bleed each radiator, one by one to release any trapped air. Once all the radiators have been bled, it may be necessary to repressurise the system.

Step 6: Run system normally for 4 weeks
Allow the system to run normally for a period of 4 weeks in order to flush out any sludge or build-ups.

Step 7: Turn off the boiler, mains water supply and drain down the system
To remove the P11, follow the same instructions from step 1 to completely drain the system.

Step 8: Turn on mains water supply, refill the system and restart the boiler
Repeat step 4 to refill the system after draining.

For ongoing protection, you may want to combine P11 with the Everbuild P14 Central Heating System Inhibitor. In this case, once P11 has been circulating in the system for 4 weeks, repeat steps 1 to 6 using P14 instead.