If your home uses a central heating system with water-filled radiators, it can be concerning to turn on the heating and have the radiators stay cold. However, most of the underlying causes of this problem are relatively easy to fix. Use these five tips to figure out what the issue is and resolve it.

1. Check the Radiator Valves

Water-filled radiators have valves that allow you to turn off radiators individually. If you have accidentally closed these valves on your radiators, they won't heat up when the central heating system is turned on. Open the valves fully on both sides of each radiator to see if the radiator gets hot.

To open a valve, you need to turn it anti-clockwise. If the valve has seized up, you can try applying a lubricant to see if you can persuade it to move. If it still won't move, you might need to contact a heating engineer who can replace the valve.

2. Bleed the Radiators

Radiators sometimes fail to heat up because there is air trapped inside them. Usually, when trapped air is the problem, the radiators are hot at the bottom but stone cold at the top.

You can release the trapped air by bleeding the radiators. Use a radiator key to unscrew the valve at the top of each radiator. You should hear a hissing noise followed by a trickle of water. Once you see this water, you can close the valve again.

3. Power Flush the Central Heating System

Another problem that can occur with water-based central heating systems is a build up of sludge inside the radiators. Power flushing is a process that removes this sludge to allow radiators to heat up properly. A sign that your system needs power flushing is that your radiators are hot at the top but cold at the bottom.

Contact a central heating repair service to schedule a power flush of your system. Plumbers generally recommend power flushing a central heating system once every few years to keep it clear of debris and sludge.

4. Look for Problems With the Boiler

In addition to your radiators being cold, do you also have no hot water? If the answer is yes, then there is likely a problem with your boiler. It could be as simple as the pilot light having gone out, in which case relighting the boiler should resolve the problem.

If you cannot work out what is wrong with your boiler, then you need to contact a heating repair service. A malfunctioning boiler can be dangerous, so you should not try to repair it yourself.