Expansion vesel blowout

[hypersonic]

Titan Flomaster Unvented DIRECT Cylinders
Etills > Plumbing > Hot Water Cylinders > Titan Pressure Hot Water Cylinders > Titan Flomaster Unvented DIRECT Cylinders
150L Titan Flomaster Indirect

The expansion vesel fitted to the above lasts abot 3 - 6 months and then devlops a blowout or leak around the seam.
I have just fitted a new expansion tank for the 4th time.
This can't be right does anyone know what can be causing this?

Thanks

Wayne

 

[david williams]

what new expansion vessels have you put on it [ make/type etc]

 

[hypersonic]

what new expansion vessels have you put on it [ make/type etc]

I have fitted a Watts 12L Vesel as below:
Toolstation > Heating > Tanks & Vessels > Expansion Vessel

 

[bobpape]

I have not actually done an unvented course, but being an ancient plumber things like
how much pressure is on the vessle prior to heating.
the fact that the more pressure the higher the temprature needed boil the water

Take the fact that at sea level water boils at 100c
The water in a vessle pressurised at 50psi boils at 150c. (ball park)
So long as the pressure and temperature is maintained nothing much can happen
But as soon as you reduce the pressure by opening a tap the water changes to
steam and in the process expands thousands of times, and causes an explosion,

There is a demonstration on utube,

I would suggest that in hypersonics case the water is being heated a little too much, not quite boiling at sea level but enough so that when a tap is opened the resulting
expantion is more than the pressure vessle can take,

I repeat I have not done an unvented course and I have not got the foggyist idea how the manufacturers overcome the inherent problems,

 

[david williams]

is vessel exploding or just developing a leak as i do not know this cylinder i assume this vessel is fitted on incoming main,have you asked cylinder manufactor

 

[hypersonic]

is vessel exploding or just developing a leak as i do not know this cylinder i assume this vessel is fitted on incoming main,have you asked cylinder manufactor

Just developing a leak. Not actually exploding.

 

[Beeline]

Have you checked pressure at outlet (to see the PRV is working as it should) also check stats as overheating of the cylinder could stay below blowoff level but create extra pressure. Also check your safety devices, i would expect one of them to vent to the discharge pipe if pressures are reaching enough to blow a seam.
Good luck, and let us know what it was when you suss it!

 

[Plouasne]

Suggest that you try these people, link below, they do have on page 2 the formula for working out the expansion vessel size, and they make the vessel so that you can just change the bladder instead of the whole unit, and I would suggest that you use a proper potable water expansion vessel rather than one suitable only for central heating



[DLMURL="http://www.rwc.co.uk/prod-CAT6.html"]EXPANSION VESSELS - Reliance Water Controls[/DLMURL]