Combi Losing Pressure Cant Find a Leak!

[sharpshooter]

I have a ferroli boiler, less than 8 months old and it constantly loses pressure after use. It loses approximatley 0.5 bar everyday, so I have to keep repressurising the system by refilling lost water. I discovered a small leak from a drain point in the system and put the loss of pressure down to this. However, I fixed this last week and still the loss of pressure remains constant.
I can find no other evidence of a leak and have ran the system at 30 degrees in hope to stop water evaporation so I could find it, yet no avail.
Is there some other reason my pressure could be escaping?
Also, if there is a leak in a wall or some space I cannot see, can I add "rad weld" or anything as in car cooling systems to seal it?
Thanks, all ideas welcome.

 

[oilman]

.... if there is a leak in a wall or some space I cannot see, can I add "rad weld".....

Yes. Not sure how it will cope if the leak is in a wall or concrete though.

 

[ChrisR]

Don't use Rad Weld - there are solutions made for heating systems! Ask about the different ways of getting them in the system, at a plumbers merchant.

 

[oilman]

What's the problem with Radweld?

 

[bradleybear]

check your safety valve and expansion vessel. The safety valve will be connected to a pipe, which should go to outside and should be visible, normally straight behind the boiler. Check to see if this has been dripping. If the system wasn't commissioned correctly, a bit of muck can stop the safety valve from shutting properly.