what would cause a copper hot water storage cylinder to collapse?

[Marty32]

Evening all

Just looking for some scenarios so I don't ending up making any mistakes out in the field?

Cheers

Mar

 

[marvoni]

I remember my Grandmother use to buy me the Look and Learn magazine every week, I've still got many hundreds of them in a box somewhere. I suppose nowadays Google has made this kinda publication redundant.

Just out of interest, what would you call the type of hot water cylinder in the photo above, is it just known as an immersion heater in the UK or does if have another name?

 

[tamz]

Finally got it to work :smile:

 

[tamz]

Just out of interest, what would you call the type of hot water cylinder in the photo above, is it just known as an immersion heater in the UK or does if have another name?

An unvented cylinder by the looks of it.

 

[Bernie2]

Hmm! Way back in the Winter of 63 there were loads of collapsed cylinders mostly due to frozen vents and cold feeds. Seen then so flat they where more like wheels than cylinders. There are a few things that can cause it though, but I would have to rummage around in my memory to find them. Before they brought out the water regulation that every cylinder was required to have a free flowing vent pipe you got all kinds of things happening like that.

 

[SimonG]

Never seen it but seems a bit of a throwback to physics at school and the boiling water in the old gallon metal can, screw the cap on and watch it implode. Those where the days, complete with the old vinegar, bicarb and red food due volcano and diy fire extinguisher. I'm sure I'd enjoy redoing my school physics lessons now.

 

[WHPES]

I remember at school - bicarb in the loo and vinegar and washing up liquid in the cistern, and .......woosh!

 

[Bernie2]

A variation we sometimes saw, was the top dome of the cylinder parting from the seam. It was quite spectacular on one house the dome was about 25mm away from the rest of the cylinder held up on a column of water. It had exploded instead of imploding. But in those days a hot water tapping could be taken from the circulating pipes (Primaries) or virtually anywhere else on a cylinder beside the usual place at the top. It was very common in those days with coal fires to run the water off if it got too hot.

The problem was if the vent and cold feed where blocked in the roof space, you could still draw the expanded hot water off. Then when it stopped coming out the tap, if you turned the tap off the remaining hot water cooled and contracted sucking in the sides of the cylinder because it could not get air or water to fill the void when the water shrank from hot to cold. You could also get other problems as well. The cylinder cold feed often fed the cold sanitary ware in the bathroom before the same pipe went to feed the cylinder. The vent or expansion pipe often fed the bathroom and back Kitchen before venting over the tank or out onto the roof. The pipe work could run all over the place up and down in and out and all kinds. It was great fun but looking back highly dangerous.

 

[WHPES]

It doesn't take a lot of suction to collapse one - they are only wafer thin, not a lot thicker than a paint can and we all know how easy it is to dent those.

They collapse pretty well when I bash them up with a sledgehammer before I take them for scrap.

 

[stevetheplumber]

we collapsed a huge cylinder back in the early 80s it was a townhouse in the west end that had a early form of sealed system that had been designed by the architech as the council wouldnt let them put tank housings on the roof cylinder was on top floor we only went there to change some taps turned of cold feed ,didnt know there was no vent and opened the taps 3 floors down gravity did the rest luckily it was a subbed job and they stood the costit doesnt need much preasure to collapse a cylinder as they are not designed to withstand negative preasure

 

[Mickyplumb]

Evening all

Just looking for some scenarios so I don't ending up making any mistakes out in the field?

Cheers

Mar

Was called out one of these years ago. A DIYer had fitted a pump to his 36x18. He took the hot supply straight off the vent about 10 inches from the top of the cylinder. It was an old gravity hot water system, no cylinder stat so with looking at why the boiler stat was set at, he probably had 80 degree stored DHW! When he switched his shower on, obviously the pump was coughing and spluttering and in his infinite wisdom he fitted a non return on the vent thinking that the pump was sucking down the vent ! He'd never heard of cavitation and obviously at some point the pump sucked harder that the tank down service to deliver.....hey presto .......a collapsed cylinder. His 36 x 18 became a 24 x 14 !!!!!!!!

 

[TTB]

Finally got it to work :smile:

These are Dublo tanks and real early ones , i have also known cylinders collapse when the water level has been too high in the F&E tank were the water level has been above the vent. Water is drawn off and as the vent is under water this creates a vacuum in the cylinder.

 

[tamz]

1950's vintage

 

[TTB]

1950's vintage

Could very well be the bottom dished ends are brazed into the side wall of the cylinder body
and still being made by IMI , well Kingspan now.
Dublo Indirect

 

[tamz]

The newer ones sit on steel rings

 

[Bernie2]

In the 70's we often got cylinders that seemed paper thin and they got dented as Plumbers struggled to fit them in. They looked beyond repair. But once filled with water and banged with your arm on both sides at the same time they often went back into shape. If that never worked cap all bosses and pump with air.