Fitting an expansion vessel?

[xd400]

Hi, I hope someone can help.

I'm going to be fitting an external expansion vessel as the one inside the combi boiler is shot.

I've been doing a fair amount of googling and there is various advice given. A few things I'd like to work your brains on.

- I gather it is recommended to install the vessel close to the boiler on the return pipe. Though others state it's not essential. Can anyone explain why closeness to the boiler is beneficial?

- Is there an issue with installing the vessel on it's side?

- How is air prevented from being trapped on the water side of the diaphragm? Especially since there is no flow through, let alone an air vent.

- I've seen vessel kits which also have a filling loop with them. Are these to allow easy connection to the filling loop section of the return pipe?

 

[Dan Robinson]

• Depends on the boiler - but close as possible fro neutral point.
• No
• It isn't. Doesn't matter anyway - air will eventually be absorbed by the water anyway.
• No.

 

[Agile]

The EXV is filled with air first either at manufacture or at installation.

The pressure of that air forces the diaphragm against the opposite side of the EXV thus leaving no space for any air there.

When filled with water the diaphragm moves across as the air is compressed until the volume of air is reduced to about 2/3.

Then as the system water expands the increase in pressure compresses the air further and the diaphragm is pushed further over.

Tony