CH Expansion Vessel Location

[andy.hide]

I am in the process of converting my open vented CH to a sealed system. I have read Ed's very helpful FAQ but have a question which I am not sure about.

I plan to take a tee off the boiler return and fix the expansion vessel, pressure gauge, check valve kit and pressure relief there. The expansion vessel will actually be mounted at a high point in the system meaning it will trap air rather than water in the wet side of the vessel.

Does this matter or do I need to fit an air vent in the pipe run slightly higher than the vessel so that I can remove the air when the system is filled ?

My thinking is that it should not matter but correct me if I'm wrong.

TIA for any help.

Andy.

[PeTe33]

I think you'll find they come with a 3 bar relief valve as part of the kit. so you plumb the safety outlet to the outside world and just turn the knob to open the valve to bleed.

or.... to prevent the requirement of bleeding through the valve why not just T off the vertical run to the vessel and stick an auto-vent right on the top which will make it a bleeding doddle to re-fill etc for the sake of an extra £10.

or something.

:¬)

[PeTe33]

Should have pointed out the wet-side of the vessel is at the top, the air is at the bottom so addition of a vent is easy if you feel the need.

[Ed Sirett]

You should be fine.

Note: There must be no isolation valves between the boiler and the relief valve. The boiler's manual may also give some hints about the layout.

[fred]

While that makes sense, the instructions for my expansion vessel said wet side down, valve at top. I bought a kit from BES noticing that it was more expensive than the individual parts but thinking that some mythical parts might be found in the kit. There was a manifold in the kit but that was promptly junked when the boiler installation instructions showed the expansion vessel on the return side and the pressure relief valve (& gauge) on the flow side. That made more sense to me so I just used threaded to compression adaptors to connect the vessel and relief valve to the system at their most convenient positions, it just made the system fit together better.