EXPLODING UNVENTED CYLINDER

apart from a drain cock (rubber washer?) it hard to tell what the solar side has wrong with it but i always fit a gate valve between pipework and a drain cock
all the expansion, PRV and controls must be fitted elsewhere or aren't fitted at all - Sauna anyone?

Both relief valves were connected into the soil stack so open to atmosphere. In fact all 3 prv's were.

The PRV's didn't blow because the pressure was normal, the expansion vessel failed for whatever reason, but it wasn't pressure related.

look again at the picture as from what i can see the TPRV and the PRV are connected by just a straight piece of pipe and one elbow with both outlets facing each other, can't see an outlet at all between them??

Doctor Drivel said:

So you assume. Nevertheless, a violent explosion occurred, and it was not because of the discharge pipe.

Click to expand...

So even though there was a violent explosion in your opinion doesn't appear to be any damage whatsoever in the immediate surrounding area.

doitall said:

The PRV's didn't blow because the pressure was normal, the expansion vessel failed for whatever reason, but it wasn't pressure related.

Click to expand...

sorry but pressure must be involved, even if a small pressure as no pressure wouldn't do the damage done might only be water pressure but it is still pressure!

kevindgas said:

look again at the picture as from what i can see the TPRV and the PRV are connected by just a straight piece of pipe and one elbow with both outlets facing each other, can't see an outlet at all between them??

Click to expand...

That's what I see too.

Bigstonebolloxwaterburnerdrivelsystemsdoctor is a to55er as we all know, but alas he is not a complete to55er but an incomplete one. Whether an unvented cylinder has blown up in the UK or not a valid point he makes; all be it much too often, is that unvented cylinders can be dangerous in the wrong hands.
Most of us have seen a stat by-passed at some time or other.
Most of us have seen a pressure relief valve that some idiot has stopped from dripping by fitting a stop end on it.
If it hasn't happened already it is a probability as I see it that one day these two types of idiot will get together to make one of these babies blow.

I agree that the safety messages about UV cylinders should be spread far and wide. Everyone should know the dangers of unvented like they do with gas.

What I disagree with is the same as everyone else does. There is a difference between spreading a safety message and scaremongering which is what Bigstonebolloxwaterburnerdrivelsystemsdoctor has done. Unfortunately the bad advice already given by this schizo has probably invoked more expense and danger to unsuspecting OP's than half a dozen exploding UV cylinders.

By posting on here most of us assume a duty of care and offer the best advice we know. At the same time we realise that no one can have a 100% accuracy hit rate. What I'm trying to get across is that most of us act in a responsible manner most of the time.

Bigstonebolloxwaterburnerdrivelsystemsdoctor is an attention seeker whose motives are more self centered and not worthy of this forum.

I dont want to see a ratings system on here on the grounds that sometimes OPs could downrate an adviser simply because they didn't like being told of the bare truth of their situation, like that doyle who trashed his perfectly good fireplace for the sake of a few 'pretty' railway sleepers the other day. Another reason I wouldn't like to see it is that could create competitiveness which I don't think belongs on a forum.

A positive thing is that a ratings system would provide the best opportunity to rid us of to55ers like Bigstonebolloxwaterburnerdrivelsystemsdoctor
Maybe it is now time for DIYnot to consider the introduction of a suitable Ratings facility

ajstoneservices said:

kevindgas said:

look again at the picture as from what i can see the TPRV and the PRV are connected by just a straight piece of pipe and one elbow with both outlets facing each other, can't see an outlet at all between them??

Click to expand...

That's what I see too.

Click to expand...

Look towards the bottom and you can see the tee, the Op confirmed it was piped into the soil pipe. Also picks up the Htg Prv

When I say pressure related, I mean excessive pressure, (Above 2.5-3bar)

Slugbabydotcom said:

maybe it is now time for DIYnot to consider the introduction of a suitable Ratings facility

Click to expand...

more an UNsuitable rating facility

dia

for the life of me i cant see it the t&p is connected to the prv and that aint right

The OP stated on Screwfix that there is a tee in the pipe and it goes to atmosphere.

IT EXPLODED!!! It did.

• If any of these cylinders are played about with they can explode.
• 20 years down the line without a service (few know about servicing), they can explode.
• If they are poorly made they can explode.

The key word is explode

There are no risk alternatives, responsible people should fit those. A house in Hampshire had its roof lifted because of one of these cylinders.



The cylinder on the ground is clearly steel and unvented and this lifted the roof.

Apart from a few on this thread, everyone is attempting say they don't explode. They do explode and when they do it is with devastating effect. Such destruction is not worth it, when a no risk alternative is available.

I would advise anyone with one of these cylinders to install on the hot draw-off pipe near the cylinder a quality make additional pressure relief valve set one bar above the pressure reducer valve. You never know the source of the safety controls on the cylinders and some of them are cheap and nasty.

ajstoneservices said:

Doctor Drivel said:

So you assume. Nevertheless, a violent explosion occurred, and it was not because of the discharge pipe.

Click to expand...

So even though there was a violent explosion in your opinion doesn't appear to be any damage whatsoever in the immediate surrounding area.

Click to expand...

The OP said it was violent. It would be to rip apart that metal. The OP was a only a few minutes behind the bang - it was still steaming.

Stop telling yourself lies. IT EXPLODED This is not something that is flippantly dismissed. Do not pretend it never.

ajstoneservices said:

dia

for the life of me i cant see it the t&p is connected to the prv and that aint right

Click to expand...

The T&P and Prv is quite often connected together before the tun dish, it shows it like that in the book.

In this case the pipe from the Prv runs uphill, which is not good practice, and there's no visible tun dish, maybe one round the corner.

Agree with slug ,

i cannot understand why you all bite at BB or whoever it is and to be honest i think it is someone who posts on here regularly and has an alter ego to wynde people up and it works.
Its simple under certain conditions unvented will explode there is documented evidence and pictures to prove it no matter what country it has happened in or how it happened.

But people have a bee in there bonnets about defending them.

On the other hand if anyone ever asks on here about fitting a flueless fire everyone is up in arms calling them death traps and POTENTIAL KILLERS.
i would imagine europe/world wide they have killed less than exploding cylinders

Doctor Drivel said:

I would advise anyone with one of these cylinders to install on the hot draw-off pipe near the cylinder a quality make additional pressure relief valve set one bar above the pressure reducer valve. You never know the source of the safety controls on the cylinders and some of them are cheap and nasty.

Click to expand...

that is the first sensible thing i have seen you post so far an additional PRV is a good idea
No one is saying they can't explode as you rightly say some are very substandard
glad to see you have finally posted a picture (see it wasn't that hard was it)
but it would be nice to know all the facts on why it exploded was it installed correctly? or had it been tampered with afterwards?

also this is a different cylinder to the other pictures and very small so can't make out what it was!