On 29 Aug, 23:28, Percy Picacity wrote:
"Dave Plowman (News)" wrote :

In article ,
* *Percy Picacity wrote:
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.

Then they need to be bent to fit. Use a bending spring and perhaps
some heat.

That's not easy as they are very short pipes, and one has a side branch
brazed on near the end, which branch is too near a bend to use a tee, I
presume. *But I may get better results if I loosen the joints at the
other ends of the pipes (ordinary compression), before refixing the
heat exchanger. *I want to redo the whole thing when I have firm ideas
as to whether to use washers and what type.

--
Percy Picacity

You can buy a Regin fibre washer pack with a couple of 1/2" 3/4" and
1" flat washers for a couple of quid. Clean the metal joint surfaces
thoroughly and if the threads are scaled wire brush them and put some
silicon grease on the threads and the inside of the union nuts so they
will tighten without overstressing the things.
The pipe ends should lie flat on the protruding threaded part of the
heat exchanger. If they don't you should loosen the other ends of the
sections so they will. When the Heat exchanger is tightened then
retighten the other ends and all should be fine. It is wise to keep an
eye on these joints and nip up if required before any weep develops
into a leak. The Firebird Combi is a decent unit but the heat
exchanger requires monitoring. In hard water areas it sometimes
pinholes between the domestic and the sealed system side, however this
is not a regular event by any means.

John