Welding a crack in a heat exchanger

[damorad]

Is it possible/advisable to fix leaking heat exchanger by welding.
I think I can see the crack at the back. Its about 2" long. The exchanger does not leak until the system is running, ie heat exchanger warm and under pressure.

The boiler is a Potterton Suprima 60, closed system.

Ta much
Damo

 

[cozzmic]

You could try internal leak sealer or if you are going to weld it you'll need rods for cast iron. Have seen cast welded before but it was on flue pipe.
Or go the whole hog and get a replacement H/exchanger.
You could try scrap merchants or e-bay for a second hand one but you'll have to wait till next week cause of the hols for the merchants.

Ps have a happy, if cold new year.

 

[Slugbabydotcom]

Try the internal leak sealer first. If that doesnt work then bin it. Just search diynot on 'suprima' and you will soon see what a naff boiler they are.

 

[damorad]

How would I deal with using a leak sealer, would it not just travel all around the system and be seriously diluted where its needed. Is the heat exchanged too hostile an environment for this to work in

On the issue of it being a naff boiler. Yes it has given me lots of problems in the past including the PCB needed lots of dry joints re-soldered but it has been working okay until this happened....

 

[Slugbabydotcom]

It works like radweld in your car radiator.
If you can imagine egg white, which is a poor mans tin of radweld, it dissolves in the water but coagulates on contact with air at the point of the leak so long as the water temp is high enough.

I believe there is a topic in the sticky section about getting additives into the system.
Is your system open vented or sealed?

I know of one instance where this stuff lasted a year on a cast iron HE, and when it started leaking again was re-added and is still working now another year on.

This is probably the most popular stuff to use, but there are others if you search the net