How To: Drain Your Central Heating System in 5 Easy Steps

Your central heating system may need to be drained down for a multitude of reasons; to repair a leak, change a radiator, replace a boiler, or for general maintenance duties such as cleaning and flushing central heating pipes.

It can seem like a daunting task, but we can guarantee you that it’s not as scary as it sounds!

We’ve put together a simple guide to follow in 5 easy steps. The following method is for an open-vented system.

Step One – Turn the Central Heating Off

Before you begin this process, you’ll need to ensure that the boiler has been switched off at the programmer. A few minutes after this has been done, you can then switch off the main electricity supply to the heating system and get started.

This is usually a fused spur switch; located close to the programmer.

Step Two – Connect the Hosepipe to the Drain Valve

After you’ve checked that both the central heating system and boiler have been turned off, the next step is to connect the hosepipe to the drain valve on the radiator you’re working on first. When doing this, it’s important to remember that if you live in a house with multiple stories, to start upstairs first and then make your way downstairs once this has been completed.

You can tighten the valve with a jubilee clip – and we’d recommend placing a towel or container underneath the connection point in order to catch any drips of water that might escape during the process.

Once the hose has been clipped onto the outlet, lead it outside and place it in a drain.

Step Three – Open the Drain Valve

Using an adjustable spanner, you’ll now need to open the drain valve by turning it anti-clockwise. Once you’ve done this, water will begin to flow out of the hose at a fairly gentle rate.

Step Four – Open the Bleed Valves

This step ensures that the pace of the flow from the drain valve increases – the water will now begin to flow through the hose steadily.

Make sure you use the bleed key to open the air vents (this should also be done anti-clockwise). You’ll begin to hear a sucking noise – don’t be alarmed! This is just the air entering the radiator.

We’d advise carrying the aforementioned cloth or container with you as you go, just in case the water spills slightly.

Step Five – Check on the Hosepipe

Nearly there! The last step is to check on the hosepipe outside to make sure that there’s water coming out of it. If there is, leave it for around 10 minutes and then carry out the same procedure on the radiator’s downstairs.

If you notice that after 10 minutes water is still coming out of the air vents downstairs, it might be because the radiators in your home are individually piped from upstairs. In this case, all you’ll need to do is drain down the radiators individually.

After a little while, you should begin to notice that the water coming out of the hose has slowed down significantly – when this happens, you’ve successfully drained your central heating!

When you’re finished, all that’s left to do is fill the system back up, which simply means that you can repeat the above in reverse order.

So, there we have it! A task that many people don’t trust themselves to do is actually relatively easy – if you follow along with these instructions step-by-step, we have no doubt that you’ll be able to do it too.

How We Can Help

If you still feel a bit unsure about how to drain your central heating system – don’t worry! That’s what we’re here for. If you have any questions you can get in touch with us by phone or email. An experienced member of the Haven® team will be happy to help.