How to clean Worcester boiler condensate trap

How to Clean Worcester Boiler Condensate Trap Easily!

Last updated on April 12th, 2024

Worcester boiler condensate traps can get very dirty and eventually blocked if they are not cleaned out which means your boiler will not fire up.

They get full of all sorts of weird gunk and sometimes bees and other insects that get in through the flue terminal outside.

I have been servicing boilers for over a decade and I have cleaned my fair share of condensate traps.

Here I’ll explain how to clean and give my best advice based on my on-the-job experiences.

Worcester hot water temperature dial

How to Clean Worcester Boiler Condensate Trap

If you have your boiler serviced regularly then your condensate trap should be cleaned out then.

If not, then cleaning it every year or so could stop it from getting blocked and causing your boiler to lock out.

To clean a condensate trap you need to remove it from the boiler, run it under a tap and keep shaking it vigorously while filling it with cold water and emptying it.

How to remove a condensate trap:

  1. Turn the boiler off and isolate the electric supply at the spur if possible
  2. Remove the casing
  3. Remove the black rubber tube on the side of the condensate trap
  4. Push the clip up on top of the trap with a small screwdriver
  5. Twist the trap anti-clockwise
  6. Pull it forward to remove it from the boiler
Worcester Condensate Trap Removal Video

Make sure to have a bucket underneath to catch any condensate water that comes out.

How to clean and refit the trap:

  1. Pour out the dirty condensate wastewater from the trap into a sink and fill it with fresh water
  2. Shake the trap vigorously and empty
  3. Repeat until all the gunk inside the trap is removed
  4. Fill with water and hold straight above the sink, let the water come out of the bottom
  5. Fit the trap on the connection at the top and click into place
  6. Refit the black rubber tube

Condensate Trap Full of Water

A condensate trap should always be full of condensate wastewater. This is completely normal.

When it fills with water from the flue it will partially empty out of the bottom and into the condensate pipe and then to the drain.

Having the condensate trap full of water stops the poisonous flue fumes from coming through the trap.

This is what traps are made for. Just like traps on sinks are always full of water to stop smells and creepy crawlies coming through.

If your trap is not emptying, it must be blocked.

Worcester boiler condensate trap
Worcester condensate trap

Condensate Trap Blocked

If your condensate trap is blocked then you need to clean it out. 

If it’s blocked with solid substances that can’t be removed then you will need to replace the condensate trap.

Cleaning or replacing the trap will unblock it but if it’s still not working then it’s probably your boiler condensate pipe blocked.

You will need to find and fix the blockage in the condensate pipe.

If your condensate pipe is frozen then this will need to be thawed out before resetting the boiler.

You should also learn how to stop a condensate pipe from freezing in a cold winter.


Cleaning a Worcester boiler condensate trap is easy but it is recommended to get your boiler serviced every year and the trap will be cleaned during the service.

If you’re starting out as a heating engineer then this will be one of the easiest jobs to learn and a very common one to do.

Feel free to ask me any questions in the comment section below and I’ll try my best to help.

Please share this post if you find it helpful.


Should a Worcester boiler condensate trap be full of water?

Yes, a condensate trap should always be full of water. When the trap is full to the brim it will partially drain but they are designed to be full of water.

Where is the condensate trap on my Worcester boiler?

The condensate trap on a Worcester boiler is inside the boiler at the bottom and slightly to the left. You can’t miss the trap once the casing is removed.

How do you stop a Worcester boiler condensate pipe freezing?

To stop a boiler condensate pipe from freezing in the winter you can insulate the pipe outside and fit a trace heating cable.


  • Steven Reid

    I am a full-time plumber and Gas Safe registered engineer. I incorporated Housewarm Ltd. in 2011 to provide heating and plumbing services to homes in Newcastle upon Tyne, England. I now blog about what I've learned over the years to help DIYers and plumbers.

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3 thoughts on “How to Clean Worcester Boiler Condensate Trap Easily!”

  1. I have cleared out my condensate trap and refit it, however now the condensate appears to leak out of the top where it connects to the slump… is the lug at the back supposed to lock into the groove or just align? I feel as though it has not been connected correctly but I can’t seem to get it to ‘click’ into place when connecting to the slump… is this normal?

  2. Charlie

    I’m having problems with my bosh boiler! It loses pressure which I refill water into the system and boost my heating/water….. though then the pressure jumps up to 3 bar…….. do you know what could be the issue here?

    1. Steven Reid

      The expansion vessel doesn’t have any air in so needs to be recharged, or possibly replaced.

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