Expansion Vessel losing all pressure in hours?

[Harvest Fields]

No idea. But I have drained a few and topped them back up and never been back to change one even though I have serviced them.

 

[ShaunCorbs]

@dan_the_plumber @Harvest Fields

Seeps through the rubber, as rubber is permeable

 

[Harvest Fields]

@dan_the_plumber @Harvest Fields

Seeps through the rubber, as rubber is permeable

As previously stated. Learn something new everyday.

 

[dan_the_plumber]

condensation is water vapour suspended in air until it is cooled below it's due point. At which time it becomes water. Granted this may happen if your expansion vessel is in an unheated area, but not in any great quantity.
Membrane or to give it its full name 'Impermeable Membrane' is not permeable. If it were it wouldn't be very good at its job.
A far more plausible cause of water on air side of membrane would be a small hole in membrane or compromised seal.
Also not ever being called back to an address is not evidence that your original repair was successful, in fact you may find it to be quite the opposite.

 

[ShaunCorbs]

condensation is water vapour suspended in air until it is cooled below it's due point. At which time it becomes water. Granted this may happen if your expansion vessel is in an unheated area, but not in any great quantity.
Membrane or to give it its full name 'Impermeable Membrane' is not permeable. If it were it wouldn't be very good at its job.
A far more plausible cause of water on air side of membrane would be a small hole in membrane or compromised seal.
Also not ever being called back to an address is not evidence that your original repair was successful, in fact you may find it to be quite the opposite.

Have a read of the process of diffusion of water through solid substances

 

[dan_the_plumber]

I've looked that up. An interesting concept. Although in my opinion wouldn't lead to much water being on air side. Maybe a bit but, generally if you've got more than a squirt coming out the Shraeder then your vessels knackered.

 

[Harvest Fields]

Also not ever being called back to an address is not evidence that your original repair was successful, in fact you may find it to be quite the opposite.[/QUOTE]
It is when I have been back to the same property on consecutive years after the repair to service the boiler.

 

[oilmark]

Never heard of that before. How does the moisture get into the air side of the vessel to begin with?

When they are recharged with a foot pump water goes in with the air depending on humidity. Think they're filled with nitrogen from new and I have read that if nitrogen leaks out then replace vessel?!?
I have always pumped them back up and not had problems.