On 11 Jan 2004 08:00:03 -0800, (RJ) wrote:

IMM & Andy

That isn't what I wanted to hear - but my head tells me you are both
correct.

IF I could get a plumber to even consider coming around I'd be keen to
wash my hands. I can't yet get one to even quote within a month!
I'll try again on Monday. Thank god the gaffer tape is holding!

So as far as the pressurised tank goes - I'll leave it to the pros to
fix/replace - unless I go for a heat exchanger unit. I'm happier with
wiring than plumbing and have just read up on these - and think I
could cope with them.

Andy - you are correct about the red central-heating pressure vessel.
Though not sure I understand what you mean by "In this case you have a
sealed system and you would use an indirect heat bank with its own
header tank built in."

Your heating primary circuit is sealed and the red vessel is there to
absorb the expansion of the water in that circuit as the boiler heats
it. Inside it there is a diaphragm with air or nitrogen behind it.
The alternative would have been an open vented system which has a
small header tank open to the air typically in the loft.

With a heatbank, the water in the bulk of the tank is not maintained
under pressure, it is fed from some kind of header tank open to the
air. If your heating system had been open vented, you could have
connected the heatbank directly to the primary circuit and have the
bulk water inside part of that circuit. The expansion of that water
would be taken care of by the header tank. This would be called a
direct heatbank since the bulk water in the heatbank cylinder also
runs through the boiler.

However, when you have a sealed primary system as you have, the
pressure can be anything up to 3 bar and the heatbank cylinder is not
designed to take that. To get around this, the heatbank can have an
indirect coil (rather like your existing cylinder) and the bulk water
inside is heated indirectly - the water in the coil remains part of
the primary circuit and is sealed and under pressure from ther red
expansion vessel.

You still have to have provision for the heatbank water to expand and
this is done with a header tank. You could do this by having a
separate header tank in the loft, or some manufacturers (e.g. DPS)
offer packaged heatbanks with the header in the top of the package
immediately over the heatbank cylinder itself.

With the indirect arrangement, you end up with three lots of water:

- the primary circuit, under pressure as it is today and feeding an
indirect coil in the heatbank.

- the heatbank water, open vented and heated via the coil to 75-80
degrees rather than the 60 of the existing cylinder.

- the mains water which is heated as required using the heatbank water
via a heat exchanger with a separate pump to the heating pump to
circulate it between heatbank and heat exchanger,





Without taking the pi$$ too much - do you have any make/models of
tanks you think may suffice that I could research more to see if its
in my capabilities? My research suggests its doable if a little
complex...

If you buy a packaged heatbank it's not that bad. You should be able
to hook it up to the existing plumbing quite easily.



(Note 8/10 for DIY is my rating for other bits I've done - not
directed specifically at plumbing where I'd say its a bit lower - so
point taken over saftey)

ALL of your help is much appreciated so far.

Regards

RJ (near Heathrow)

Andy Hall wrote in message . ..
On 11 Jan 2004 01:54:00 -0800, (RJ) wrote:

Semi tempted by this thought - but for 2 things - 1 getting the right
seal - I can't find any mention of this particular setup on the web
anywhere! and 2 - the top of the cylinder looks so rusted, that if all
the rust is removed and cleaned away, it'll be impossible to reseal as
the cylinder is so pitted and rusted...

My neighbours had theirs replaced (by their landlord) - So I'll call
them and see if they can take a look - whilst on DIY issues I'd say
I'm 8/10 er, I'm not at all ofay with this type of setup....


Then don't do it. This is a cylinder of hot water at 60 degrees,
stored under mains pressure - up to about about 4 bar. Really,
according to Building Regulations they are supposed to be (legally
speaking) installed and maintained by a plumber specifically trained
on pressurised cylinders.

Normally, I will tackle anything with respect to plumbing, and I am
far from being a fan of government regulation but looking at your
photos, I wouldn't entertain the idea of trying to fix this cylinder.
Even if you can clean it up, and it looks doubtful to me, then you
would have to be very sure that it all goes back together properly.
What you don't know is whether the cylinder has in other respects
corroded and deteriorated. I would say that this really isn't worth
the risk.

If you want to DIY this, then IMM's idea of a heatbank does make
sense. It would be quite easy to plumb this in, although a bit of
wiring would be needed, and it has the advantage that the contents of
the cylinder are not under pressure. The heat is stored in the
cylinder in the form of water at low pressure and then this is pumped
through an efficient heat exchanger to heat the mains water. With a
vented primary system you can connect directly. I notice on yours
what looks to be a small pressure vessel for the heating (red) at the
corner of the picture. In this case you have a sealed system and you
would use an indirect heat bank with its own header tank built in.

Alternatively, you could just get the cylinder replaced with a new
pressurised one. However this really is a job that is supposed to be
done by a trained professional. If you were a 10/10 person on
plumbing then I'd suggest that you make your own value judgment on
whether to DIY, but since you say 8/10, then I would think carefully.
If you get it wrong then you can create a dangerous situation.







"BigWallop" wrote in message ...
"The Natural Philosopher" wrote in message
...
BigWallop wrote:


Now go out and buy a big wire brush and some scouring pads and clean the
whole up. Once youve done that, then more than likely you'l be able to
reseal the plate and tank back together no problem with some proper
neoprene
sealing rings. But it all has to be shiny clean.



Do you really think it can be resealed to 5 bar tested?
Safely?


Not disagreeing, just curious.


Depends on how competent the OP is, although the banding does a lot of the
work in pulling the two bits back together again, and as long as the correct
seals are used, then it is a job that can be done by someone who's good with
their hands and head (as in a bit of brain power). :-))


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