expansion vessel replacement

[rotherman]

I Need the expansion vessel replacing on my Baxi 105E, the easiest option appears to have an external version fitted, Altecnic do an extensive range, but how do you calculate what size is needed,4, 8, 12ltr ???.
Would it need its own filling loop, pressure release valve and pressure gauge or would the boilers own work with it.
ANY ADVICE WELCOMED
Rotherman

 

[baxpoti]

The easiest option is to replace the one in there.

If you do fit an external vessel fit it as close to the boiler retun isolator as possible.

You cannot oversize a vessel, premature failure of yours maybe, because it was too small from the start.

Fit at least a 12L

 

[Prof.plumb]

Size depends on size of system, how many rads are there? You do not require additional prv or filling loop.

 

[Biggles..]

Vessels are normally sized at 10litres per KW of boiler divided by vessel manufacturers constant.

Normally equates to 1litre/KW.

 

[rotherman]

The easiest option is to replace the one in there.

If you do fit an external vessel fit it as close to the boiler retun isolator as possible.

You cannot oversize a vessel, premature failure of yours maybe, because it was too small from the start.

Fit at least a 12L

Thanks for the advice and it was the expansion vessel in the boiler thats failed.

 

[bengasman]

If, for whatever reason, you fit one that is too small, you are back to the same problem. If you fit one that is far too big, you have overspent by a tenner, but you will have very little pressure variation.
That should make the choice rather simple.

 

[rotherman]

Size depends on size of system, how many rads are there? You do not require additional prv or filling loop.

Thanks for your response, there are currently seven radiators and the boilers in the loft.

 

[Biggles..]

is it deffinately a 105e and not the 105einstant as this would also make a differnce.

 

[rotherman]

is it deffinately a 105e and not the 105einstant as this would also make a differnce.

SORRY, its the 105e INSTANT !!!!!!. Why ??.

 

[kevplumb]

cos it uses the ex vess as a water store

 

[rotherman]

cos it uses the ex vess as a water store

Cheers, I origonally tried repressurising the onboard expasion vessel, it lasted about a week before I was back where I started, the valve wasn't leaking water and the pre heat appears ok, so I thought an external expansion sounded the best option, would it still work.

 

[baxpoti]

is it deffinately a 105e and not the 105einstant as this would also make a differnce.

For what reason?

Fitting an external vessel is an approved repair on both models.

 

[Biggles..]

i didnt think you should fit an external one to an instant if it failed cos of the preheat, But you'll know best so guess i now know for the future.

 

[rotherman]

i didnt think you should fit an external one to an instant if it failed cos of the preheat, But you'll know best so guess i now know for the future.

INTERESTING, if the onboard expansion vessel has failed, will the preheat store still work, is there any way of checking it, should I turn off the preheat function ???.

 

[baxpoti]

The preheat will still work, it just heats a larger amount of water.