Using a vented hot water cylinder on an invented system

[CarlJa]

Hi,

Can you use a vented hot water cylinder on an unvented system?

Many Thanks,

Carl

 

[SJB060685]

Apart from possibly not able to withstand the higher pressures, they also won't have tappings for crucial safety devices.
If you're thinking of doing a DIY job, think again and get a professional in. If you want stored mains pressure hot water then you need a purpose built unvented cylinder.

 

[Ric2013]

If on the other hand, you just mean that a vented cylinder, with the secondary plumbed in conventionally to an open vent and cylinder feed cistern, is to have its primary coil connected to a sealed primary boiler circuit, then there is nothing wrong with that.

 

[CarlJa]

If on the other hand, you just mean that a vented cylinder, with the secondary plumbed in conventionally to an open vent and cylinder feed cistern, is to have its primary coil connected to a sealed primary boiler circuit, then there is nothing wrong with that.

A vented cylinder replacing an unvented cylinder, I assume this is a no go as mentioned above, a vented cylinder will not be able to withstand the pressure of mains water. Is this correct?

 

[ShaunCorbs]

No you can’t as there only rated to 1 bar maximum

 

[king of pipes]

That's a no no I'm afraid , a sealed system on the primary side is sometimes ok but the coil needs to be able to withstand the high pressure this information is normally on the cylinder itself , a vented cylinder cannot be directly fed from the mains water supply it's not designed for that, you need a unvented cylinder which has safety devices fitted should there be a failure on your system. Kop

 

[John.g]

Just read on bords.ie where someone has just noticed that there is vented written on his "steel" HW cylinder which has been running unvented for the last 10 years, no details yet of any other requested info. It has a mains PRV and cylinder EV & a TPV.
Had a quick look at vented SS cylinders but don't see any info like you see for copper cylinders to reflect Grades 1,2&3 copper. My own copper vented cylinder conforms to Grade 3.

Grade 3 test pressure is 1.45 bar and is suitable for 10m working head

Grade 2 test pressure is 2.2 bar and is suitable for 15m working head

Grade 1 test pressure is 3.65 bar and is suitable for 25m working head

 

[ShaunCorbs]

T and p on the cylinder ? If so it’s not vented

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

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