Hot water expansion

[Johnyc86]

Hi
Just wondering in a vented hot water cylinder,when hot
Does the water expand back up the cold feed into tank or via the vent pipe

 

[king of pipes]

No it expands up the vent pipe off the top of the cylinder the pipework may feel hot a meter or so above but it shouldn't heat the water in the cold water storage tank , if this is happening then your system needs attention.

 

[Shower Engineer]

Hi
Just wondering in a vented hot water cylinder,when hot
Does the water expand back up the cold feed into tank or via the vent pipe

Water heated in the cylinder will push cold water from the bottom of the cylinder back up the cold feed pipe, the level of the water in the cold feed cistern and vent will always be equal/level. As KoP says the vent can get warm, this is especially true if the vent runs vertically off the cylinder due to a phenomenon known as sacrificial circulation where hot water flows up the centre of the vent and water that has had a chance to cool on the outside flows back down into the cylinder.

 

[Johnyc86]

Water heated in the cylinder will push cold water from the bottom of the cylinder back up the cold feed pipe, the level of the water in the cold feed cistern and vent will always be equal/level. As KoP says the vent can get warm, this is especially true if the vent runs vertically off the cylinder due to a phenomenon known as sacrificial circulation where hot water flows up the centre of the vent and water that has had a chance to cool on the outside flows back down into the cylinder.

But does this apply to unvented aswell??

 

[ShaunCorbs]

But does this apply to unvented aswell??

no unvented is a different kettle of fish and why you need to be qualified to work on them