boiler leaking when CH is on only

[androvsky]

Hi,

I wonder if anyone can advise what can be causing that. In short - I've got an old Minimiser boiler (I know - it's old and should be replaced) which started leaking last year. I called BT engineer who replaced small tank inside and the problem seemed to be gone. Turns out it was not, it simply became too warm for central heating to be triggered. I just diagnosed that it leaks only when central heating is on. It does not leak when hot water is on. It's also fine when boiler is off. I can see the leak only when boiler is working in central heating mode, a lot of water located of the top of the tank I mentioned. It's flowing down the pipe (i.e. outside the pipe of course) from big metal box, combustion chamber, I guess.

As I don't want to be charged again for parts I need and work which is not necessary - could anyone advise what can be not right?

Regards,

Mark

 

[dcawkwell]

Heat exchanger leaking. New boiler time.
Unless there is a pipe in the boiler leaking somewhere but from your
description sounds like the heat exchanger.

 

[45yearsagasman]

There was a problem with the seals on the flue on these and this may be the problem. Bit of dismantling required for a RGI. Don't spend too much money on this lemon.

 

[androvsky]

Why is it not leaking when hot water is on? Are heat exchangers separate for CH and HW? I should also add that combustion chamber is not cracked - water flows down the pipe thread. It simply appears outside the pipe going down from combustion chamber rather than than inside.

 

[androvsky]

I think is is a flue problem - water leaking seems slightly mild. These are good news - my problem seems minor, the only problem is that a lot of time (taking to pieces the whole boiler) is required to fix it. Thank you very much for your answer, at leask I know where I stand.