"Grant Erwin" wrote in message
...
I have a 10 year old hydronic heating system in my home. There is a boiler
and it leads to a special tank which holds the heated water, which is
circulated on demand through wall registers. The thing that makes this tank
special is that it also holds potable water, i.e. a hot water tank. The
heating and potable water never mix, ever.

My tank has developed a pinhole leak right up on the domed top. I cannot
imagine that there wasn't a manufacturing defect, but the warranty says
that if the house is sold the warranty ends at 5 years. Before I buy a new
tank at a whopping $1200, I want to at least try to fix the pinhole. My
heating system guy shook his head and said "it would never hold" but I
don't see how I have much to lose. There is almost certainly some kind of
liner which I'd have to worry about, so I'd want to use minimum heat.

Anyone have any idea how something like this might be patched? I was
thinking of trying a soft solder perhaps.

GWE

I would get some JBFix, a small square of metal window screen, and make a 2
x 2" patch.

My experience with these is that they corrode from the inside. If you were
to cut this open, you would see corrosion marks. This was so with several
aluminum hot water heater units people brought me out of motorhomes. They
had a pinhole, and not enough metal that was thick enough to weld to. It
just blew holes. Finally, we did the JBFix thing, and they lasted a little
while longer, but just until the next cancer popped through at another
place.

It's just like freeze plugs. You ever change a freeze plug in a motor
block. I did it once, and replaced only the one that was leaking. After
firing it up, a week later, another started leaking, as they were all the
same age, and all in the same state of corrosion. So, I pulled the engine
AGAIN, and did all the plugs. A lesson.

This is not to say that you might patch this tank, and see another ten years
of problem free use.

I have had some incredible results with JB products when it was the last
best thing to do before replacement. And, for a few bucks, you could do
several patches.

Just drain to make sure it's dry, and clean the surface and sand it a bit.

Let us know what you do and how it works.

STeve