Bizarre boiler leak problem

[markinyo76]

Hi All,

I wonder if you can help me with a problem with my boiler that is driving me mad...

I have an Alpha CD32C combi boiler that is *periodically* leaking from the bottom of the boiler (onto the floor).

What is odd about this is that it happens irregularly - I had it happen twice in a week then nothing for 2 weeks and then again today.

What happens is that about a pint of dirtyish water leaks from the bottom of the boiler and then it just stops.

It's not a constant leak and I cannot find any source - there are no visible leaks from any of the joints etc.

I've noticed the system pressure has decreased slightly on each leak.

Here's what I don't understand:

- The pressure gauge says it is at 1 bar cold. When heating it gets to about 1.4 bar. Both valves on the filling loop are closed and the pressure is not increasing when cold.
- Most of the time when it's heating there is no leak.
- The condensate pipe isn't blocked, I checked it.
- There is a pressure relief pipe that goes out of the side of the house, but there is no water coming out of that, it just leaks out of the bottom of the boiler!!

This only started happening when I repressurised the boiler about 3 weeks ago - it was at originally 0.7 bar and I repressurised it to about 1.2, well within the 'green' zone on the gauge.

Because it's only intermittent I don't know what I can do... anyone any ideas what might be causing this?

Thanks.

 

[gigz]

Is the nut on the pressure relief valve tight ? (where the copper pipe joins to the valve) If its not, its possibly dripping from there if the valve opens.

 

[dcawkwell]

Pressure relief valve may be faulty or not even connected.

Similar the condensate pipe may not be connected or leaking.

Auto air vent is also another possibility.