Enough already. I want to get on with my life...
So, let's look at the issue you posted where your water pressure was dropping so you had the repair for £500 carried out.
It is obvious that the 'control block' (the new part consisting of a pressure reducing valve and pressure relief valve) is new. Based on the fact that you've not had any maintenance carried out on your unvented cylinder to that point, it is quite likely that the filter inside the pressure reducing valve had become blocked leaving you with a much lower flow rate - which you would describe as a loss of 'pressure'. As it would be completely calcified (bunged up) the correct resolution was applied. That is, to fit a new control block.
Herein lies a problem. A non manufacturers part would cost no more than £50. Adding 25% is reasonable so a parts bill of £70.
IF it were a 'genuine' part (read further stitch up) from the manufacturer then it could well be double that. All in all tho, nowhere near £200.
As you are in London, the most expensive plumbers are Pimlico Heating. They charge £157 per hour. So, your maximum labour charge should have been approx £150. Again nowhere near the £300 you were charged.
Moving on. Your system is a mess. It needs urgently resolving in order to be both compliant and safe.
As a landlord, you have a legal obligation to have it appropriately serviced, but you also have a duty of care.
What you need, is an experienced G3 engineer to look at your system and to set it right. You will need a full service on it to make sure it is fit for purpose and working most efficiently. This
will involve some pipework modifications to make it comply with regulations and to remove
your neck from the noose should anything go wrong and it harm someone, or do damage to your home.
Insurers look for things like this in order to escape their moral responsibilities. If you had a water leak on the hot side, insurers
may well ask to see the cylinders maintenance history. If you cannot provide it then they can, and do in my experience, simply walk away from the claim due to YOU not carrying out required maintenance.
The fact you simply did not know means nothing. It's entirely
your responsibility to find out what you don't even
know to ask about
I strongly suspect that the engineer who turned up was NOT G3 qualified. Obviously I cannot know, so IMHO, it should form a line of enquiry from you to them as to the person attending's appropriateness of qualifications. The reason you have a right to know, is the poor state of the cylinder installation and its lack of servicing. Every G3 engineer I have ever met would have pointed out all of these things when there or reported post event simply to cover their backsides
Further, the engineer should
NOT have worked on it if unqualified.
It is NOT dangerous in the short term so do not panic.
It does however need fixing urgently and appropriate resolutions applied. Please make sure he/she checks the rating of the control block components even though they are new. They MUST be rated the same as original to comply with safety accreditations.
Overall, it's a bit of a bugger's muddle really. The good news is that you are now placed to both understand what was and to move forward with some considerable confidence.
You have now learned that as a landlord your head is in a noose continually. You really must both investigate and take seriously those various responsibilities but, unfortunately, agents also try to BS you by wittering on about aspects of things just to scare you - e.g. annual legionella assessments and deep cleans.
Anyway, I hope we have been able to help. When you return, as I know you'll not be able to keep away for our combined charms, you'll be a little wiser. Please update us.
Sorry it was so long
