Best Leak Sealer on the Market?

[AndyT68]

I've got a small crack in my Ideal Classic FF250 heater exchanger which leaks (1 or 2 drips per minute) when cold.
Before I go for a heat exchange replacement, I thought I would give a leak sealer a go. Question is, which is the best? Fernox F4?
P.S. Boiler is 12 years old, heat exchanger 8 years old.

 

[muggles]

Not sure whether leak sealer will fix something dripping at that speed, but worth a go I suppose. F4 should be as good as anything

 

[oph]

Id be asking myself why on earth your on the second main HX for an ideal classic in such a short space of time.

The only good boiler ideal ever made except the mexico

 

[muggles]

I hadn't spotted that, there's some wicked corrosion going on there, these things are pretty solid. There's something wrong with your system