Combi Boiler Install.

Hello,  I previously posted this thread in the consumer rights category but was told I may have more luck posting here.  me and my partner are looking for some advice after having a Combi boiler installed. 

We have gone through BOXT and the whole installation has been something out of a nightmare.  The first engineer who came out damaged the property, cracking our hallway walls and caused a leak due to not removing the old water tank correctly.  The leak caused water damage to our hall ceiling.  They sent a new engineer out to fix the other issues left by the original installer and BOXT paid for the damages and even admitted the work was rushed and sloppy.  

We thought this would be the end of our problems but 4 weeks on we have another leak that has caused the ceiling in our kitchen to bow and needs to be removed and repaired.  The shower has been ripped out by an emergency plumber to find the source of the leak being the pipes feeding the shower.  To back track… when we first enquired about the boiler install, the engineer on the phone warned us that our shower may not be compatible with the boiler, as it was a gravity fed shower.  He urged us to check with our installer before going ahead, which we did.  The first engineer installing the boiler said it would be fine, and obviously his work was not of a good standard or one we trusted, so when the second engineer came to fix the problems, we asked for his opinion.  He said that if the shower was going to blow, it would have done it straight away and we would have already known about it.   

The plumber not connected to BOXT said that the issue was that the shower was not compatible with the boiler and the engineer that BOXT sent out today have said it’s an issue with our pipes and the change in water pressure that has caused it, which “they see all the time” and not an issue with the shower.  If this is the issue… my question is why is it just the shower pipes that have begun leaking and why were we not warned of this before installation?! Surely we should have been told that this was a possible issue that could arise and be asked if we wished to go ahead with the install?  

We are not money grabbing people, we got a new boiler to make our lives easier and now our house that we are trying to make a home is falling apart.  We’re upset and frustrated and feel we have not been properly informed and just want to know who is correct in this instance as BOXT are unlikely to cover the cost of repairs as they don’t see it as their issue.  

The shower we have is a Aqualisa aquavalve 609 and the boiler we have had installed is a Worcester Bosch Greenstar 4000 30kw. 

Any help or guidance with this would be greatly appreciated


  • Ayr_Rage
    Ayr_Rage Forumite Posts: 499
    100 Posts Photogenic Name Dropper
    edited 25 August at 1:29PM
    According to the Aqualisa website your valve is suitable for a combi boiler and the installer was correct in saying it would be fine.

    Unfortunately it seems that your existing pipework has been the latest issue and ascertaining whether that was capable of handling the increased pressure over the gravity system would not have been part of the survey.

    You've just been unlucky. 
  • ThisIsWeird
    ThisIsWeird Forumite Posts: 2,863
    1,000 Posts Name Dropper
    Almost certainly as Ayr_rage says.
    The actual shower mixer itself should be capable of handling water pressures waaaay over that found in domestic situations - I suspect it'll be 'warranted' to 10bar, as most other taps, radiators, and other watery things are.
    What does sadly happen, is that weak pipes joints - which have coped easily with the fraction-of-one-bar pressure from a tank - simply fail when subjected to the typical 2-3bar from pressurised systems. Ie, it was a situation waiting to happen. 
    Yes, they probably do see it 'all the time', but actually only in - what? - one in a few hundred cases?
    Since it likely wasn't their fault, and not something you could have foreseen, it does sound like a 'simple' insurance job.
    One day you will look back on this and laugh. :neutral:

  • HanCan
    HanCan Forumite Posts: 6
    First Post
    Thank you!  We just needed to know who was right and who wasn’t in the situation as the work done previously wasn’t great and didn’t want to be getting walked all over!  I also joke that I have the worst luck… guess it checks out!  :s
  • ThisIsWeird
    ThisIsWeird Forumite Posts: 2,863
    1,000 Posts Name Dropper
    HanCan said:
    Thank you!  We just needed to know who was right and who wasn’t in the situation as the work done previously wasn’t great and didn’t want to be getting walked all over!  I also joke that I have the worst luck… guess it checks out!  :s

    I can't blame you for questioning whether BOXT were trying to fob you off, having made such a dog's ear of the first job. But they do seem to be completely separate issues.
    What makes one shower suitable for 'gravity' and another 'combi' or 'unvented' (ie, the latter two powered at mains pressure) is not the strength or fabric of the mixer valve, but simply the size of bores inside it. 'Gravity' showers need to be very free-flowing, as there's little pressure behind the water flow. Mains-driven showers can have more 'crude' internals, as there's enough water pressure to push adequate water through regardless!  But, both types should be designed for the '10 bar' standard.
    That applies to pipework and fittings too - it should all handle in excess of 10 bar; plastic, copper, gravity or mains pressure - all of it. But, sometimes a joint hasn't been made properly, or looseness or corrosion has set in over time, and it 'copes' only because the pressure is so low. It is common, therefore - and they should all do it - for plumbers to advise that there could be existing issues with the original pipework which are brought to light only because the pressure has increased from 'gravity' to 'mains' with such a conversion.
    You've just been unlucky. The increased pressure has simply exposed a pre-existing fault.
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