On Sat, 18 Feb 2006 19:04:17 GMT, "Pete C."
wrote:

Grant Erwin wrote:

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 think you're actually referring to an indirect fired domestic hot
water system.

The "boiler" normally feeds your hydronic baseboards directly with a
circulator pump and zone valves if needed. You DHW normally is provided
one of three different ways, in-boiler tankless DHW coil, separate
standalone water heater with it's own burner, of indirect fired DHW from
a separate heat exchanger tank.

The indirect fired DHW normally has a separate heavily insulated storage
tank with a heat exchanger coil in it. This heat exchanger coil is
normally plumbed to the boiler as an additional zone and there is a
separate thermostat for the DHW tank. It's rather the opposite of the
in-boiler tankless DHW setup where the DHW is in a heat exchanger coil
in the boiler tank.

If this is the case, the tank itself holds the potable DHW water so
anything you use to patch it must be potable water safe. The actual DHW
tank temperature normally should not exceed 130 degrees and your normal
domestic water pressure. The problem is that if the cause of the leak is
general corrosion as opposed to one defective spot, you could have the
heat exchanger coil ready to go as well and the potential for cross
contamination. If you have antifreeze in the boiler side of the system
this would be particularly bad.

I think you need to lookup the exact brand / model tank and determine
exactly what you are dealing with before proceeding.

Pete C.

I would agree - but if I was fixing it I'd braze it with the O/A torch
and the "blue" brazing rod. I'd drain the tank down and open it to
atmospheric pressure, sand the area around the pinhole perfectly
clean, and flow brass on in an area about the size of a quarter or
half-dollar.
*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***