How do I fix low water pressure on my Vaillant boiler?

Low boiler pressure can be fixed by repressurising the boiler via the filling loop. High boiler pressure can be fixed by bleeding a radiator until enough water has left the system to reduce the pressure to operating levels.

How do I put the pressure back in my Vaillant boiler?

Repressuring a boiler without a filling loop

  1. Turn off the boiler.
  2. Insert the filling key into the keyhole and unlock it.
  3. Turn the valve next to the key until water flows through it.
  4. Monitor the valve until it reaches the recommended level for your boiler model.
  5. Close the valve and turn the boiler back on.

How do you fix a low pressure boiler?

4. Can I fix low boiler pressure myself?

  1. Switch off and allow your boiler to cool.
  2. Double-check that both ends of the filling loop are securely attached.
  3. Open both valves, to allow cold mains water into the system (you should hear it)
  4. Wait for the pressure gauge to read 1.5 bar.
  5. Close both valves, one after the other.

How do I increase the pressure on my Vaillant boiler?

As a general guide, follow these steps:

  1. Turn off the boiler.
  2. Inspect the boiler filling loop.
  3. Turn the isolation valve anti-clockwise until the line on the valve is directly in line with the pipe.
  4. Turn the handle valve anti-clockwise.
  5. Watch the pressure gauge as you do this.

Does bleeding radiators affect boiler pressure?

Yes. During the process of bleeding radiators, air is released from within them, which in turn reduces the pressure in your boiler system.

What happens if the pressure in boiler is too low?

If the pressure on your boiler is too low, then your central heating may not work, and if it’s too high, then it will be under too much strain and could also be prevented from working.