it says on the IQ site that non americans will get a slightly lower result as the questions are USA biased. so technically we could all be geniuses. that should really cheer someone up. 
Where to buy hot water cylinder
- Thread starter North
- Start date
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Correct, they disabled the safety devices.
But, that's why in the UK the regs require that you only fit a complete system comprising the cylinder and all the controls and safety devices supplied as a package by the manufacturer.
There are in fact several safety devices. There is a pressure relief valve at the inlet - normally part of the pressure reducing valve. There is a separate pressure relief valve on the cylinder, which also has an over-termperature function (ie it lets water out (to be replaced with cold) if the cylinder is overheating).
Why the Mythbuster one went off so violently is that the temperature was so high. Once the pressure is released, the water instantly turns into a very high volume of superheated steam - thus propelling the cylinder upwards like a rocket. The superheated steam is in itself highly dangerous and will "cook" the flesh off you if you are in the firing line.
So our safety regs require multiple redundant safety devices. TWO pressure relief valves. And TWO temperature control devices - one is the safety valve, the other is the requirement to not have any uncontrolled heat sources.
With these safety devices correctly fitted, unvented cylinders are fairly safe.
In addition to what Simon listed there are one or two more!
An electric immersion heater has a separate overheat stat.
A boiler heated cylinder has to have a spring return motor valve which is powered through an overheat stat.
Vaillant say that THEIR own cylinder does not need the motor valve when its own temp sensor is correctly connected to their boiler.
There do not seem to be any known cases of UV cylinders exploding in the UK. In other countries they do not have all these safety devices and have been some cases of cylinder exploding.
View media item 66512
Tony
An electric immersion heater has a separate overheat stat.
A boiler heated cylinder has to have a spring return motor valve which is powered through an overheat stat.
Vaillant say that THEIR own cylinder does not need the motor valve when its own temp sensor is correctly connected to their boiler.
There do not seem to be any known cases of UV cylinders exploding in the UK. In other countries they do not have all these safety devices and have been some cases of cylinder exploding.
View media item 66512
Tony
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Sorry T - wrong there. One went up in Ware - Ask MickyG about it (not that it was one of his).
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