Got a small leak inside the boiler on the loop (pressurised) which heats the water tank.
Do the sealants work? If so, is it better to use a full dose (it’s only a 20l max loop) at once, or do half today and then half in a couple of days. If this doesn’t work, I’m looking at a new boiler, so I’m not too concerned about the gumming up of the system – within reason.

yes they do work, not always but have had success with the Fernox one in the past. Managed to get customer by for a few weeks till I could change the boiler.

I was going to try the sealant stuff on my 30 yr old boiler, but the leak has since sealed itself with rust, which has formed nicely around the tiny hole in the back of the heat exchanger 🙂

Done – lets hope the jizz does the biz!

Fernox works very well.

Edit, if you know where it is, can you not repair it?

It’s an oil condensing boiler – warm flow uhe 120
I *think* the leak is in the condensing unit. When the heat store was put in, the plumber fitted the circulation pump the wrong way around and there was a banging coming from the boiler which turned out to be a pipe moving inside cos the water was flowing in the wrong direction. The leak maybe something to do with that. If the sealant doesn’t work I’m going to take delve a little deeper and see if warm flow do spare condensing units.
Any other common leak areas to also consider?