It's a bit concerning you think this discussion is some kind of battle. Unless you understand more than the people who made the safety rules, I'm sure they took into consideration the considerable aggregate cost of all the pressure relief valves and pipework which mostly sit around doing nothing, so to overrule them and suggest it can be capped off is pretty reckless.
I can only hope that when this thread comes in Google searches in future it's clear to anyone else how bad an idea that is!
Just in case
http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3770
Equally reckless is the manners in which one conducts this so called " a discussion" that turns it into an ugly and a reckless debate.
So if one was being genuinely helpful and concerned about safety issues, like the issues in one in my picture I posted, where someone noted the flue pipe to him didn't appear to look "right", he either knew what might be wrong with it, but could not say it as he may not be a qualified gas safe engineer to comment or he feared being ridiculed! so he simply left his comments for others to comment on, he simply said "Is the flue in Mike from London's £3500 installation correct apart from being unsightly?"
so someone comes along and says "No" (meaning yes there is a problem) without explaining why. This is not a helpful advice or is it? It left me guessing as to why? I am not an RGI.
and then following on from there, it turns into a nasty sarcasm and insults, where I was called an Idiot and I reported this offence, so this turned into a nasty debate where
another picture I posted was quoted that had some potential problems, again the problems were not pointed out by so called helpful advisors on DIYnot forums, instead what followed was a more sarcasm and abuse, where you also joined in John, without giving any good reasons as to what is the potential problem with that installation, leaving me again to guess what may be the problem. I knew it was not usual for PRV discharge pipe terminating into a washing machine drain pipe, but I thought nothing of it other than this must also be an alternative acceptable method, and I never asked my installer if that was right.
So now, instead of pointing out the exact nature of problem or advising me how to correct that problem, I was called an Idiot, and when I tried to guess the possible breach that could cause a potential problem, you went about water gushing out at 120c at 3 bars, I have yet to see any combi boiler gushing out water at that ferocious rate, and gave you my logical reasons why this is highly unlikely to happen on a combi boiler (due to safety cut out devices such as overheat sensors and switches) and what its consequences may be on my particular installation, not prove me wrong by quoting links to previous hazardous situations where a combi boiler was not involved but a system boiler and hot water storage tank that went wrong.
So this person who insulted me earlier then commented to my comments where i said that my boiler of 24 years age has been into service and has never ever discharged any excess boiling hot water pressure unless I overfilled it to begin with, and when once its EV had an internal leak, it dripped from PRV as there was no room for water to expand, and yes it dripped not gushed out, as the heat builds up slowly, to which he replied "Well in that case let's all ignore the rules and cap off these pointless safety devices? After all.... Yours has never been a problem. So this is not helpful but sarcasm.
So John, where did I even suggest that we can do away with PRVs? Please don't extend this pointless debate. I have never advocated blocking off PRVs. In fact I would go one better and fit another as a back up just in case one seized up.
So please before you accuse me of wrong doing, have a look at the attitude of some advisors on here who not only are useless at offering any sensible advice but also use sarcasm and insulting words that leads to such arguments and meaningless discussions.
1.Why not just offer good, safe and solid advice like in my case one could say that flue is not correctly slopped and should have slopped towards the boiler.
2. That PRV discharge pipe should not have been terminated into a common drain point where condensate drain and washing a machine outlet is also connected and if possible give your reasons to back up the argument and highlight potential problems. This is more helpful to everyone, and a learning curve for many.
(I believe knowledge and experience should be shared )
I am pretty sure this gas safe company installer would have looked into all this and then decided he could take this route safely, he would have considered all the circumstances of a PRV discharging excess pressure into a common point that also drains condensate and washing machine outlet and any issues associated with blocked drains would have surely crossed his mind.
May be he ruled out the coincidence of a boiler going drastically wrong and having to discharge boiling hot water at 120C and jet of steaming hot water whilst the drains may be blocked at the same time, perhaps if you debate further onto this, it may actually unblock the blocked drain (Steaming hot water under pressure! ) ( perhaps I am being a little sarcastic here too, my apologies for that) what other consequences are there???? perhaps steam may start discharging from the washing machine door, and soap drawers? or perhaps I don't know what else, i already mentioned the pressure could enter condensate trap and enter the boiler's combustion chamber, by which time the boiler would have been knackered any way, so please tell me if you know what other reason is there that this arrangement is not acceptable apart from not being normal, how would they discharge PRV on 3 or more story high flats or buildings having own boilers? I will welcome your comments, please no sarcasm.
What I did was just tidy up, I did not carry out the original installation, so fortunately someone pointed a potential problem with the flue slope, but he was not too sure so he asked, and the replies that came were meaningless, unless one also explained why?
So you came into this ugly debate that had nothing to do with the title of this thread, we debated about how often does a PRV discharges its content?
You even admitted in your above post I quote "I'm sure they took into consideration the considerable aggregate cost of all the pressure relief valves and pipework
which mostly sit around doing nothing, so in the debate I argued that my own boiler now 24 years into service has never discharged any content, and let us assume if it did, could you tell me the worst case consequences of that PRV discharging into a common drain?
I have nothing against you and have always respected your views, sarcasm always attracts sarcastic remarks, did i suggest anywhere that you can safely block off PRV, unless said so in a sarcasm to a sarcastic comments.
I know perfectly well the Prime function of a PRV, and that it should never be blocked off. ( not only me, most people do )
And I do appreciate that some good came out of my posting pictures, as it highlighted potential issues, but still no one had the guts to say to me directly what the exact issues were and why and a possible solution. Only that I managed to guess logically what the issues might be, I was offered no real help but plenty of sarcasm, now that I have been made aware though indirectly through sarcasm, with great difficulty, to these potential problems, i will be asking my installer to look into it and suggest a possible safe solution in the name of safety, withholding safety information is a CRIME.
(Sorry for the long rant and having to defend myself against aggression!)