British Gas cant seem to fix it?

Discussion in 'Plumbers' Talk' started by arsenalboy, Jun 11, 2021.

  1. arsenalboy

    arsenalboy Member

    I posted a couple of weeks ago about Valliant 831.

    A quick recap, it had broken down in Jan and British Gas replaced 3 parts i.e., Diverter Valve, Expansion Vessel and Water Pressure Switch.

    We have a contract and paid the 50 excess.

    Because of cold spring the CH only went off a few weeks back and we discovered that the radiators still heated up when hot water was run for a few minutes.

    B Gas replaced the Diverter Valve yesterday and said the one that was fitted 4 months ago was sticking, we have obviously not been charged.

    After having showers this morning the radiators are warm.

    What is going on?
     
  2. jonathanc

    jonathanc Screwfix Select

    British Gas haven’t fixed the problem or haven’t diagnosed it correctly. Simple really. You pay an insurance premium for them to fix the problem and they haven’t. Get them back time and time again until they do fix it
     
    pppmacca43 likes this.
  3. diymostthings

    diymostthings Well-Known Member

    And tell them to post a query on here...
     
  4. jonathanc

    jonathanc Screwfix Select

    because they’ll get more of a clue how to fix it!!!
     
  5. Mike83

    Mike83 Screwfix Select

    Are they changing the complete diverter and motor?
     
  6. arsenalboy

    arsenalboy Member

    Thanks for the replies and I dont know whether the diverter motor was replaced, sorry.

    I guess my question is what would cause the hot water to continue to be diverted once the diverter valve is replaced?

    I know this a problem for BG but just curious.
     
    Last edited: Jun 11, 2021
  7. Mike83

    Mike83 Screwfix Select

    When in hot water mode the motor should fully pull back on the pin closing off the heating circuit.
    If this isn’t happening it points to the diverter valve or motor.
    If the motor isn’t connected on to the diverter spindle it could also cause issues.
    When the radiators heat up in hot water mode what actually happens?
    Does the flow pipe only get hot or does the flow and return both heat?
     
    arsenalboy likes this.
  8. arsenalboy

    arsenalboy Member


    thanks for that explanation. The pipe that doesnt have the valve stays cold but the pipe without the valve heats up. Does that identify anything?
     
  9. Mike83

    Mike83 Screwfix Select

    The left hand pipe is the flow and the right is the return.
    If the right hand pipe is heating up then the water must be passing through the diverter valve and down the return pipe. I wouldn’t expect the radiators to get much better then warm as there won’t be a complete circuit for the water to flow.
    So either the motor isn’t pulling the valve fully closed or the valve itself is at fault.
    Sometimes if a plate heat exchanger is restricted then the radiators can heat up. Never had this on these boilers though.
     
    arsenalboy likes this.
  10. arsenalboy

    arsenalboy Member

    Sorry, reading this again I realise I have put in a double negative!

    It should have said the pipe that has the TRV stays cold and the one without the valve heats up.

    I am confused Mike83 by your designations for the right and left pipes being flow and return?

    I have 14 rads in a rambling Victorian house, but circa half the rads have the TRV on one side and the rest have it on the other side.

    But yes you are right, the rads only get warm and not hot and only those nearest the boiler i.e., 2 or 3, whilst the rest around the house stay cold.

    So just to clarify, it is the left hand pipe that is heating up and that is the one without the TRV.
     
  11. Mike83

    Mike83 Screwfix Select

    I’m referring to the 22mm pipes at the boiler.
    Which one heats up?
     
  12. arsenalboy

    arsenalboy Member

    Okay, so I ran the hot water for 5 mins last night and got gentle warmth from rad. The left hand pipe was hot and right hand pipe cold.

    However, and it is a big however, this morning after showers the radiator did not get warm it stayed totally cold.

    Whilst that is good news it is totally confusing? So the Diverter valve was replaced on Thursday and after showers on Friday and Saturday the radiator got warm but not this morning?
     
  13. Mike83

    Mike83 Screwfix Select

    The diverter is on the return pipe.
    There’s a chance there’s nothing wrong with it.
    Some water seems to be flowing down the flow pipe and partially reaching the radiators.
    If the return pipe at the boiler was getting warm/hot this could indicate a passing diverter.
     
  14. arsenalboy

    arsenalboy Member

    Is that a known type of issue and easy to fix.

    Appreciate your comments Mike.
     
  15. Dbosoz

    Dbosoz Member

    Hello Arsenalboy, if the flow (USUALLY the right hand 22mm pipe) is getting warm, then yes, the diverter could be sticking. But if there are new valves on, could it just be a very dirty system which needs a flush to get all of the muck out that may be clogging the valve. Do you have a filter fitted on the return (right hand side 22mm pipe), it should have one. Also, I had one of these boiler fix policies, I had loads of problems with my boiler, then went into garage where the engineer was 'changing' loads of stuff, but caught him putting the old stuff back in, he didn't even change the PCB which was supposed to be done, so mark the valve and make sure it gets changed. Hope this helps.
     
  16. Dbosoz

    Dbosoz Member

    They came out quite a few times, then the last engineer kept sending me up stairs to 'just turn the hot water on', I went back unexpectedly and saw him putting the old expansion tank back in, all he said was 'oops, what am I thinking'. I watched him also 'change' the PCB in less than 10 seconds while he had his back to me, amazing, and it looked like the 'old one' was brand new when I had a look at it, then when he had left, I checked the 'new PCB', which looked like it was a bit dirty and dusty, funny that!!!!!
     
  17. Dbosoz

    Dbosoz Member

    Not sure I understand what you are saying.
     
  18. Dbosoz

    Dbosoz Member

    Hi ArsenalBoy, My apologies, I've just read my post about the flow pipe, my mistake, the flow is usually on the left, sorry for the misunderstanding.
     

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