Just collected my new combi expansion vessel and it's the wrong one!!
I ordered it over the phone from my (reasonably) local supplier using the
manufacturer's part number taken from the short parts list in the boiler's
Manual/Handbook. All this without physically double-checking the part number
stamped on the existing vessel's green label, partly because it's a bitch to
access without removing a load of gubbins from the boiler first. The new one
is rectangular in shape and of 12 litres capacity, and the manual even
obligingly shows a diagram of it as being a rectangular part too. However,
upon (much) closer inspection, the existing and faulty unit is a ROUND one
of only 8 litres capacity, instead!

More confusingly still, the new one has the air/tyre valve located on the
top of the vessel, instead of at the bottom on the same side as the CH water
union. Nor does this tally with the diagram in the handbook, which although
of the same shape (rectangular) as the new one, shows the valve to be in the
same position as my existing round vessel, i.e. easily accessible from
beneath the boiler. This means that, assuming it will physically fit my
boiler, the valve will no longer be accessible from the top (unless you
possess octopus tentacles) for pressure checking and topping up. :-(

I have already sent an email to to Vaillant tech support asking them to
advise if I can substitute this new one for the old round one, without
altering any of the existing pipework connections etc., but in the meantime
I thought I would ask here if anyone should know why the air valve has been
relocated?

Also, as I mentioned earlier, the existing round unit is stamped as having
an 8 litre capacity, whereas the new rectangular one is stamped as being 12
litres capacity. If this (unannounced) specification change from a
rectangular to a round one is bona fide, then why would they also reduce the
capacity of the expansion vessel? I would have thought more was better?

Pah!
Nigel

In article ,
"nrh" writes:
Also, as I mentioned earlier, the existing round unit is stamped as having
an 8 litre capacity, whereas the new rectangular one is stamped as being 12
litres capacity. If this (unannounced) specification change from a
rectangular to a round one is bona fide, then why would they also reduce the
capacity of the expansion vessel? I would have thought more was better?

As far as I an tell from reading your article again, they increased
the size. Yes, a bigger one reduces the cases where an extra vessel
will be required in the installation.

--
Andrew Gabriel

In ,
Andrew Gabriel scribed:
In article ,
"nrh" writes:
Also, as I mentioned earlier, the existing round unit is stamped as
having an 8 litre capacity, whereas the new rectangular one is stamped
as being 12 litres capacity. If this (unannounced) specification change
from a rectangular to a round one is bona fide, then why would they also
reduce the capacity of the expansion vessel? I would have thought more
was better?

As far as I an tell from reading your article again, they increased
the size. Yes, a bigger one reduces the cases where an extra vessel
will be required in the installation.

No, the original round one (and fitted since new) has only 8 litres
capacity, whereas the replacement I ordered holds 12 litres.

To be more precise, the Vaillant Spares Part Number as listed in the manual
is 18-1022 (G.C. 255 346), and shows it as a rectangular unit in the
corresponding diagram. The new part I now have correctly shows that part
number and is rectangular in shape (albeit with a repositioned air valve).

However, the existing faulty part fitted to the boiler since new has the
part number 18-1030 (G.C. 283 674) stamped on it, and which needless to say
does not tally with that shown in the manual.

Nigel
p.s. The boiler is a Vaillant VCW GB 282 EH.

In an earlier contribution to this discussion,
nrh wrote:

In ,
Andrew Gabriel scribed:
In article ,
"nrh" writes:
Also, as I mentioned earlier, the existing round unit is stamped as
having an 8 litre capacity, whereas the new rectangular one is
stamped as being 12 litres capacity. If this (unannounced)
specification change from a rectangular to a round one is bona
fide, then why would they also reduce the capacity of the expansion
vessel? I would have thought more was better?

As far as I an tell from reading your article again, they increased
the size. Yes, a bigger one reduces the cases where an extra vessel
will be required in the installation.

No, the original round one (and fitted since new) has only 8 litres
capacity, whereas the replacement I ordered holds 12 litres.

To be more precise, the Vaillant Spares Part Number as listed in the
manual is 18-1022 (G.C. 255 346), and shows it as a rectangular unit
in the corresponding diagram. The new part I now have correctly shows
that part number and is rectangular in shape (albeit with a
repositioned air valve).

However, the existing faulty part fitted to the boiler since new has
the part number 18-1030 (G.C. 283 674) stamped on it, and which
needless to say does not tally with that shown in the manual.

Nigel
p.s. The boiler is a Vaillant VCW GB 282 EH.

Did the manual to which you refer come with the boiler when it was new - or
is it a later version, downloaded from the internet or whatever?

It is quite possible that there has been a design change since your boiler
was made - and that the specified replacement part is the later, larger one.
Unless it doesn't fit at all - in which case the manual's wrong!

It's *even* possible that your boiler wasn't latest spec when you bought
it - but the manual was!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In ,
Set Square scribed:


Did the manual to which you refer come with the boiler when it was new -
or is it a later version, downloaded from the internet or whatever?

Came with boiler when I bought it new about 8 years ago.
I replaced the secondary heat exchanger, which I came to understand was an
extensively modified version of the original unit, and the manual diagram
also shows the modification. So, I assumed that the manual was correct for
this part too.

It is quite possible that there has been a design change since your boiler
was made - and that the specified replacement part is the later, larger
one.

Tell me about it!

Unless it doesn't fit at all - in which case the manual's wrong!

I wasn't going to fit it just yet, as I wanted to ensure it kept pressure
after several weeks standing. Also, it being Winter, I don't want to run the
risk of being without heat/hot water should I encounter problems.
As I stated in an earlier post, I have emailed Vaillant asking them if I can
use this 'new' part, and still await their reply. However, as the current
unit is both smaller and round, I suspect the various bits of pipework
connecting it to the CH water circuit may have been especially designed to
fit that one and will not suit the new, larger unit. Unfortunately, as it is
located right at the back of the boiler, I cannot get to it to take
measurements for comparison purposes.

It's *even* possible that your boiler wasn't latest spec when you bought
it - but the manual was!

I hope to establish this when I hear from Vaillant. I would ring them, but
their Tech Support line costs 50p/min, and would rather avoid that extra
expense unless absolutely necessary!

Cheers for you interest.
Nigel

I wasn't going to fit it just yet, as I wanted to ensure it kept pressure
after several weeks standing. Also, it being Winter, I don't want to run the
risk of being without heat/hot water should I encounter problems.
As I stated in an earlier post, I have emailed Vaillant asking them if I can
use this 'new' part, and still await their reply. However, as the current
unit is both smaller and round, I suspect the various bits of pipework
connecting it to the CH water circuit may have been especially designed to
fit that one and will not suit the new, larger unit. Unfortunately, as it is
located right at the back of the boiler, I cannot get to it to take
measurements for comparison purposes.



one idea might be to return the new expansion vessel and fit an
external pressure vessel
you can then size it yourself, its far easier to maintain and will
probably work out cheaper.Depending on how much of a strip down fitting
an internal vessel is, it will be a far easier job as well

In ups.com,
scribed:



one idea might be to return the new expansion vessel and fit an
external pressure vessel
you can then size it yourself, its far easier to maintain and will
probably work out cheaper.Depending on how much of a strip down fitting
an internal vessel is, it will be a far easier job as well

Thanks for your input. However, there is not really any available space to
accomodate an external vessel within reasonable proximity to the boiler.
Besides, I don't really know how I am going to be able to completely bypass
the existing one without capping it off somehow.

By way of an update, I have just this minute received a reply from Vaillant
Tech Support, who state the following:

"Thank you for your email.

You will need to replace the expansion vessel with the same type as the one
already fitted, ie the 8 litre 181030.

Before ordering parts based on the original installation manual it is always
best to check with our technical department (01634 292392
) as the numbers are subject to change from the time
when the manuals were originally produced.

Regards

Technical dept"

So there ya go. Just as well I didn't order it online, I guess. CBA with all
that postage malarky, even though I paid a smidgen more for it from my local
shed.

Kind regards to all
Nigel