Central Heating Expansion Vessel Orientation

[Martin]

Hi Group, Could anyone tell me if there is a correct orientation to install an expansion vessel on a sealed heating system. If not is there a preferred / recommended orientation.

Thanks in Advance, Martin.

[Martin]

Been looking at past postings and found a post stating that a plumber had installed an expansion vessel upside down. I therefore conclude that there is a correct orientation but still do not know which way up is the correct way. I think the air valve should be on the bottom because then you can read the label on the vessel without having to turn your head.

Regards, Martin

[John]

Having found them in a variety of orientations without relevance to their performance since the diaphragm keeps the compressed gas/air and water seperate it doesn't really have any critical aspect. On the one hand labels are often placed so as to suggest outlet upwards (schrader valve down) but in the event of a system with a bit of sediment floating round having the outlet down serves to keep it from accumulating within the water chamber AND forms an airbell in the event of diaphragm failure. Certainly I've come across them outlet down on commercial pressure control units straight from the factory. In short whatever suits your pipework location best

[Ed Sirett]

The only issue I've encountered was that if it is being used on an unvented cylinder then the pipework should be long enough so that the normal pressure variations say 2-4 bar don't introduce fresh oxygenated water into the vessel into the steel vessel.