Underneath boiler I have a towel radiator that really needs bleeding however I'm concerned that my boiler is going to need repressurising after bleeding. Most tutorials I have seen have had 2 blue taps that you need to open in order to increase pressure, however mine has 4 black taps and a yellow tap. I can see that it also has a notice about a pressure relief valve? Sorry I'm a novice at these things but don't really want to have to call someone out. The boiler is a baxi duo tec 2 28 ga combi. Any help appreciated.

  • 1
    Suggest you to get the manual (it should be available online) and look for the section 'system filling': baxi.co.uk/-/media/websites/baxiuk/files/discontinued-products/…
    – DDS
    Apr 1, 2018 at 22:23
  • What pressure does the system operate at?
    – Paul Logan
    Apr 2, 2018 at 2:44
  • @PaulLogan The boiler operates between 1 and 2, right now it's in the middle of 1 but I'd imagine that it will drop once bleeding the radiator. Apr 2, 2018 at 8:08
  • @DDS I have looked at the manual but am a bit confused as to how my system is set up, from looking at it, I'd imagine the valves I'm looking for are the second to last ones as seen here. imgur.com/a/nbe7B Apr 2, 2018 at 8:14

1 Answer 1


I really think you have to open 2 valves as in UK systems,there's an odd use of not having a 'load' valve integrated with combi. In your case I think you have to open the valves on the 'by-pass' pipe connecting the fresh water inlet to system return.

Open the circled ones:combi valves circled

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    Thanks @DDS I have just successfully repressurised the boiler by opening the 2 valves at the front like you suggested. Thanks a lot for the help. Apr 5, 2018 at 20:37

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