A fully working central heating pump is crucial to sufficiently heating your home.

The pump increases the speed at which hot water leaves your boiler, circulates around your radiator system and then returns to your boiler.

But if your pump has an airlock, then you may seriously reduce the heating capability in your home.

Air locks often occur when air enters the central heating system and gets trapped in the pump. The trapped air will then reduce the rate at which water flows through the pump.

Fortunately, if you are suffering from airlocks, all you need to do is bleed the central heating pump.

Today, you’re going to learn how to fully bleed a boiler pump. Taking you step by step through the process, your pump will be in full working order in no time.

Does my central heating pump need bleeding?

If this is the first time you have had to bleed a central heating pump, then you probably have a few concerns.

“Will this really fix the issue?” “Will I make the issue worse?” “Should I just contact a plumber?”

First, bleeding a central heating pump is not that difficult. It’s unlikely that you will break anything that a plumber can’t easily fix. But, if you don’t feel confident doing it yourself, then you should probably contact a plumber.

Second, identifying if your central heating pump needs bleeding is easy. You will almost definitely have one of the following problems:

  • My pump is making a loud knocking sound
  • My pump is not adding pressure to my central heating system
  • My pump is quite hot

My pump is making a loud knocking sound

Pumps will generally make a slight humming sound with a minor vibration. If the pump starts making an excessive banging noise, then you probably have an airlock.

This is where the air trapped inside the pump stops the water flowing smoothly, causing the water to bang against different components.

My pump is not adding pressure to my central heating system

If the central heating pump suddenly stops adding pressure to your system, then it’s a good sign that something is critically wrong. In this case, it could be an airlock.

This is where the air trapped inside the pump stops water from flowing around your system smoothly. The air inhibits the performance of the pump and stops hot water from reaching your radiators before cooling.

My pump is too hot

Central heating pumps should be a tad warm to touch. If the pump is getting hot to the point of burning, then you clearly have a significant problem.

In this case, it could be that you have an airlock. This is where the air trapped inside the pump stops the pump running correctly. This can potentially damage pump components and can cause the pump to burn out.

Please note: If the airlock has already caused damage to pump components, then bleeding the pump may not fix your issue.

How to bleed a central heating pump

If you have one of the problems identified above, then you can almost guarantee that there is air trapped in the pump. To solve this problem, you will need to bleed the central heating pump.

Warning: Never bleed a central heating pump when hot. Scalding water could be released.

Tools needed:

  • Towels
  • Pliers
  • Bleed key or a flat-head screwdriver

Step 1 - Turn off the power

diagram showing you how to bleed a central heating pump

Make sure that the power to the pump is turned off. Do this at the fuse box and notify everyone in the home or building. Make sure the power cannot be accidentally reconnected when you are working on the pump.

Step 2 - Protect against water damage

graphic showing you how to bleed a central heating pump

First, lay down towels to protect the floor, electrics and the surrounding area. Four or five towels should cover a significant area.

Step 3 - Turn off the water at the shut-off and gat valve

diagram showing you how to bleed a central heating pump

Locate the shut-off valve (usually under the sink) and turn off the water entering your home from the mains supply. Next, use the pliers to shut off the water to your pump at the gat valves. These will be located on either side of your pump. Simply turn clockwise until touch tight.

Step 4 - Slowly remove the pump bleed screw

diagram showing you how to bleed a central heating pump

Now slowly remove the bleed screw on the front of the pump using a bleed key or flat-head screwdriver. You will notice a small amount of water leaking from the bleed valve. Keep turning the screw until it comes off completely. Keep the bleed screw safe.

Step 5 - Mop up all the water that trickles out of the pump

diagram showing you how to bleed a central heating pump

Once all the water has bled out of the pump, you will have successfully bled the air out of the pump.

Step 6 - Screw the bleed screw back into place

diagram showing you how to bleed a central heating pump

Screw the bleed screw back into place and clean up any water.

Step 7 - Turn on the power

diagram showing you how to bleed a central heating pump

You can now turn the power on.