Vented / unvented cylinders, pros and cons

[bernardgreen]

it takes out the gable end of their house who gives a feck!!

Neighbours whose houses are damaged and the emergency services who have to deal with the injuries and damage.

Is that saying that an unvented cylinder in the wrong hands can be hazardous ? Would they be more or less hazardous than a vented cylinder ?

 

[JohnD]

Eh no!! If the punter don't bother their arze getting it serviced & it takes out the gable end of their house who gives a feck!!

That's interesting.

How many times a year has that happened?

 

[flameport]

What process is used to ensure that this annual service occurs.

The same as anything else. It's the responsibility of the property owner to arrange such things. If they don't bother, then problems may occur.

While there is a small chance that an unvented cylinder could explode, they are not alone in having the potential to cause damage and destruction.
Defective gas appliances leaking carbon monoxide, gas leaks resulting in an explosion, defective electrical installations causing a fire, water leaks undermining foundations until the side of the building falls off, poorly maintained brickwork resulting in the chimney falling into someone's bedroom, rotted roof timbers causing the roof to collapse.

Dozens of possible deathtraps in every home.

 

[Dan Robinson]

Looks like I was right. Bernard wants to have a pointless argument based on ill conceived thoughts after a brief bit of googling.

 

[Dan Robinson]

This is a reasonably good explanantion of the differences that was quoted.

http://www.gasapplianceguide.co.uk/Mains_Pressure_Hot_Water_Systems.htm

When describing the safety requirements of the unvented system it doesn't give much information as to what can happen if the pressure limiting valve becomes defective and allows the water pressure to rise above the setting of the cylinder's pressure relief valve setting.

It was a terribly written piece if you ask me.

 

[PullerGas]

it takes out the gable end of their house who gives a feck!!

Neighbours whose houses are damaged and the emergency services who have to deal with the injuries and damage.

Is that saying that an unvented cylinder in the wrong hands can be hazardous ? Would they be more or less hazardous than a vented cylinder ?

Hold on, you expect all G3 Plumbers to feel responsible for every moron not willing to spend money on unvented cylinder servicing??!! There's safety devices on these units that need servicing & checking.
Don't tell me BG, you're a retired 'engineer', with too much Google time & too big a pension?

 

[shambolic]

Looks like I was right. Bernard wants to have a pointless argument based on ill conceived thoughts after a brief bit of googling.

And if we humour this fannybaws it will be another 8/9 pages and adding it all up about 30 minutes of my life I will not get back.

 

[shambolic]

I'm off to bed. Rehab in the gym at 730am tomorrow before a day of callbacks on the Tech line.

 

[Dan Robinson]

Good luck long John.

 

[muggles]

it takes out the gable end of their house who gives a feck!!

Neighbours whose houses are damaged and the emergency services who have to deal with the injuries and damage.

Is that saying that an unvented cylinder in the wrong hands can be hazardous ? Would they be more or less hazardous than a vented cylinder ?

About the same - a vented cylinder in the wrong hands can also be hazardous, as can a gas boiler, or a wet fish

 

[bernardgreen]

Don't tell me BG, you're a retired 'engineer', with too much Google time & too big a pension?

Trying to retire, but people won't let me.
Google is good but I also have access to other data sources that google does not have access to
A pension can never be too big.....

When a pressure relief valve opens, what generally happens is that excess pressure is relieved, thereby protecting the appliance.

Obviously that is the immediate safety requirement but opening a pressure relief valve can have consequences

A pressure regulating valve did fail to control pressure and the results of that failure were the reason for the discussion starting on the other forum.

Maybe I should have asked for comments about the consequences of the pressure regulator failing leading to the opening of the safety pressure relief valve.

It is these consequential things that are being discussed politely and constructively elsewhere.

 

[Dean744PiN5]

Is that saying that an unvented cylinder in the wrong hands can be hazardous ? Would they be more or less hazardous than a vented cylinder ?

http://www.dailymail.co.uk/news/art...scalded-baby-girl-death-known-unreliable.html

a very unfortunate situation that happened due to a faulty VENTED set up.

 

[Dan Robinson]

consequences of the pressure regulator failing leading to the opening of the safety pressure relief valve.

Water runs through the discharge pipe warning the user there is a problem.

What are you driving at?

 

[bernardgreen]

a vented cylinder in the wrong hands can also be hazardous, as can a gas boiler,

Yes, every piece of equipment has hazards.

When electrically heated the water in a vented cylinder might be heated above boiling point. Steam will escape via the expansion pipe so cylinder explosion is most unlikely. Heating of the water in the cold feed tank is likely and subsequent softening and collapse of that tank is possible and has in the past resulted in a fatality. This lead to the mandatory addition of a safety cut out in electric immersion heaters.

In a vented cylinder the over heated water will not be higher than 100°C so can not "explode" into water vapour. ( that is at sea level, at higher altitudes where air pressure is lower the boiling point is lower than 100°C )

Water under pressure can be heated much higher that 100°C . If a pressurised ( un-vented ) cylinder containing water above 100°C ruptures the escaping water, no longer under pressure will instantly become water vapour. This is explosive expansion.

EDIT The water temperature of a un-vented cylinder heated indirectly by gas is unlikely to reach temperatures above 90°C due to boiler controls, boiler safety devices and the limitations of the circulating water. Hence an "explosion" due to water above 100°C is almost impossible.

 

[bernardgreen]

Water runs through the discharge pipe warning the user there is a problem.

What if the user does not see the water running out of the discharge pipe. ( for example they are not at home during the day and do not think it necessary to take a torch and check the discharge pipe ).

Also add into the equation fluctuating pressures in the water supply mains.