From the FAQ

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Doctor Drivel

The MOD irresponsibly remove this post. It identifies overt errors in safety and just general operation. He then locked the FAQ thread to keep unsafe advice being there.

An Unvented cylinder is a pressure vessel and as such carries the danger that all pressure vessels carry so they are fitted with safety devices. The system is designed to FAIL SAFE.

This is wrong. Understand what failsafe means.

To prevent expansion vessel failure there are other safety valves fitted.

If the water overheated and turned to steam, the vessel could rupture, and the rapid expansion would cause an explosion. To avoid this happening a pressure reducing valve (pic below) is fitted to the inlet water to limit the pressure to about 3 bar. If the vessel fails the valve opens and the pressure is released to outside.

A pressure reducing valve will stop a rubber bladder rupturing? New to me.

Does he mean an expansion relief valve? I don't think he knows about these things at all, as he says unvented cylinders are failsafe when they are not. Failsafe is when all controls fail, it is safe. When all unvented cylinder controls fails it takes off like a rocket and takes down walls - it explodes.

No mention of an expansion relief valve and a pressure reducing valve does something magical.

Below: clearly shows the expansion relief valve on the cold feed.

3.jpg



"2. The Expansion Relief Valve is set to relieve the pressure in the system if it exceeds the 6 bar (approx 90 p.s.i) that it is set at. Normally this will only occur if the expansion vessel develops a fault or looses some of its charge, or if all 3 of the temperature-operated safety devices fail at the same time.

3. The Expansion Relief Valve can be directly connected to the Combined P.R.V/L.S./C.V or it can be installed independently, but it must always be sited between the Combined Valve and the Cylinder. A drain is connected to the Expansion Relief Valve to take away any water that does exit the valve should it operate. The drain discharges to an outside position via the Tundish.

4. The Expansion Vessel is designed to take up any expansion water that is created by the heating of the water. Water expands when heated. The expansion of the water when heated in this ‘sealed’ system causes the air in the expansion vessel to compress creating a space for the increased volume of water. The volume of water in the system will vary from 100% of its volume when cold to approximately 104% when heated to 65 degrees Celsius. The main purpose of the expansion vessel is to ensure that the Expansion Relief Valve doesn’t operate every time the water goes through a heating cycle, as this would contravene the Water Regs by ‘wasting water knowingly’. The Expansion Vessel can be screwed into the Expansion Relief Valve, although it is more normal to ‘T’-in a piece of 15mm pipe to the cold water side of the system, between the Expansion Relief Valve and the Cylinder, and run it up to a position above the cylinder and locate the Expansion Vessel at high level.

5. The Temperature and Pressure Relief Valve is designed to be both a back-up in case of failure of the Expansion Relief Valve and/or a back-up in case of a failure of the High-Limit Thermostat. The T&P Valve is located on the top of the Cylinder (and in Atlantic’s case, combined with the hot outlet connection pipe) as this is where the temperature of the water will be at its hottest. A drain is connected to the T&P Valve to take away any water should this valve operate. The drain discharges to an outside position via the Tundish "


This FAQ entry needs changing ASAP, as it is misleading to people who want good factual advice on safety aspects of appliances.
 
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=drivel again. Does he mean an expansion relief valve? I don't think he knows about these things at all, as he says unvented cylinders are failsafe when they are not. Failsafe is when all controls fail, it is safe. When all unvented cylinder controls fails it takes off like a rocket and takes down walls - it explodes.

They do not explode and they never have drivel, There has not been a single incident where an unvented cylinder has exploded or killed anyone in this Country.

Now go and quote the HSE bits to suit your argument.

The expansion vessel on the boiler (heat source) has been designed as a weak link, and that will go before anything else, instantly relieving the pressure. Even in the event of you being really really unlucky and all the other 9 safety features fail the expansion vessel cannot, it will separate.

And where does the energy come from to take the wall down Drivel, certainly not from a few gallons of water as it goes through the roof.
 
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Doctor Drivel

=drivel again. Does he mean an expansion relief valve? I don't think he knows about these things at all, as he says unvented cylinders are failsafe when they are not. Failsafe is when all controls fail, it is safe. When all unvented cylinder controls fails it takes off like a rocket and takes down walls - it explodes.

They do not explode and they never have drivel,

The expansion vessel on the boiler (heat source) has been designed as a weak link, and that will go before anything else, instantly relieving the pressure. Even in the event of you being really really unlucky and all the other 9 safety features fail the expansion vessel cannot, it will separate.


<I had to snip some drivel>
 
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Video evidence Drivel :LOL: :LOL: :LOL: :LOL: :LOL: :LOL: :LOL:

The cylinder was launched drivel it did not explode.

Where is the energy that chop the wood up.

Look at it again driver/balski
 
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Doctor Drivel

The cylinder was launched drivel it did not explode.

There was a few videos. Look at them all. The TV prog where they put one in hut and it demolished the lot. Appalling sight. Imagine children being in that! Appalling!
 
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Gentlemen. Could we please bring back some order to this otherwise excellent and informative forum and STOP arguing. Everyone is entitled to their point of view, but scaremongering and name calling does nothing for the professional image of the industry.
 
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Gentlemen. Could we please bring back some order to this otherwise excellent and informative forum and STOP arguing. Everyone is entitled to their point of view, but scaremongering and name calling does nothing for the professional image of the industry.

That is the whole point Hugh.

If unvented cylinders have exploded and killed several people a year, them drivel/balski hast to show the member the proof, not some stunt in America.
 
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Doctor Drivel

Gentlemen. Could we please bring back some order to this otherwise excellent and informative forum and STOP arguing. Everyone is entitled to their point of view, but scaremongering and name calling does nothing for the professional image of the industry.

That is the whole point Hugh.

The point of this thread is an incorrect FAQ entry. Gwaaaad!!!!

.
 
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Facts Drivel/balski black and white facts.

How many according the HSE have been killed or injured by an unvented cylinder in this Country.

I say none prove me wrong
 
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Cue the HSE quote again.... Could the good Dr give me an explanation as to why he is so keen to promote the dangers of "exploding cylinders" yet is happy to promote possibly unsafe gas installations?

Whilst Mr Keen Diy'er may be capable of installing some pipes or a new radiator does that make him ok to alter his gas installation? He may THINK he is competant, but without full and accurate knowledge of the subject he could very easily cause a fatality.

I have seen many cases of potentially dangerous gas installations, yet not one of an unvented cylinder in a domestic setting that has caused injury.
 
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Doctor Drivel

Facts Drivel/balski black and white facts.

How many according the HSE have been killed or injured by an unvented cylinder in this Country.

I say none prove me wrong

Do you mean you can't figure out the lines of failure? Gwaaard!

Wurzle, who is balski?
 
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The question was "How many"

Are you unwilling to answer this question?

Was it the same number as people stung by ladybirds?
 
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The question was "How many"

Are you unwilling to answer this question?

Was it the same number as people stung by ladybirds?



Problem to humans -
Harlequin ladybirds have a tendency to aggregate in buildings in large numbers during autumn and winter.

Many people find harlequin ladybirds a nuisance in the house, and do not wish to share their home with a few tens of thousands of harlequins

As a defence mechanism many ladybird species exude a yellow fluid (called reflex blood) which has an unpleasant acrid smell, and which can stain soft furnishings

When hungry, harlequin ladybirds will bite humans in their search for something edible. Ladybirds in houses, woken from dormancy by central heating, may bite people as there is no food available. The bites usually produce a small bump and sting slightly. There are a few documented cases of people having a severe allergic reaction to harlequin ladybirds.


Looks like its quite a few. ;)
 
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JohnD asked "Was it the same number as people stung by ladybirds?"

Balenza replies with a quote "The bites usually produce a small bump and sting slightly."

So how many sting? None. They all bite.
 

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