"Dave Plowman (News)" wrote in
:

In article ,
Percy Picacity wrote:
he pipes to the heat exchanger in this Firebird Olympic combi
boiler have joints of a type I am not used to. The pipe ends
have a flat flange which fits against a male threaded brass tube
like the tail of a tap[1], but unlike a tap connector they have
no continuation of the pipe into the tail. They have been made
with various versions of fibre washer and jointing compound, but
invariably start leaking. I suspect they may be designed to be
used without any washer, but the flanges do not lie flat because
the copper pipes are not accurately made to lie in the plane of
the joints on the heat exchanger. I feel the copper flanges
might bend or break if tightened with no washer.

Does anyone know how these joints should be made, and how to stop
them leaking? Many thanks for any comments.

That's similar to brake pipe unions on cars. Called flared. On
brake pipes it has no washer or jointing compound. And has to
withstand far higher temperature and pressure. Of course like all
such things has to be made correctly.

I'd be inclined to just clean everything and use some Fernox LS-X
jointing silicone.

Might also be worth running a fine file across the heat exchanger
mating face to make sure it's true and flat.

That was my immediate idea, but the fact the pipes don't lie in the
same plane, and would be significantly twisted to lie flat on the
joints is a bit worrying. this could be because some of them have
been bent, or perhaps imprecise manufacture. Perhaps I'll give this
a go next time one fails. The last (15mm) one I used a rubber
washer with filter from a washing machine hose, will be interesting
to see if this works for a long time. If it does, I need a source
of similarly rigidified (by the filter) 22mm ones.


--
Percy Picacity