Does Leak Sealer Work In A Cracked Heat Exchanger?

[AndyT68]

I have an Ideal Classic ff250 with a small crack in the heat exchanger which is causing a small leak - 1 or 2 drips per minute - when the system is cold.
Question is, is it worth trying Fernox F4 as a first fix?

 

[45yearsagasman]

I suppose it's worth a try as a temp fix, but the temps at the heat exchanger surfaces and inside the combustion chamber are high and there is little chance of the sealer working IMO.

 

[Agile]

I would also say that whilst it might work for a short time I doubt that it will be for very long.

I would actually use Radweld or similar product designed for use on cars.

The CH ones seem to be designed on a different principle and I would expect they would be less effective.

But the boiler is quite old and not very efficient and a replacement is the normal solution as that will save about 25% on the gas bill.

Tony