Boiler losing pressure without any leakage

[ArtemPtushkin]

Hello!

I have a combi boiler (n8 topline compact hrc 30/cw5) required to fill in 1.5 BA, 8 radiators, and heated floors in the same system.

I have a pressure loss problem, I lose ~0.3-0.4 every week without visible leakage. I had 2 plumbers and 1 guy from the boiler gas service company.

The leakage wasn't found. The expansion vessel is okay - excluded by both plumbers. The pressure relief valve is ok, the filling loop is ok.

What I did:
• turned off the floors - same situation
• checked all the visible pipes and thermostats with napkins - no wet
• bleed all the radiators after a topup

Maybe crucial for analysis:
- Once the pressure had dropped to 0.1, I thought it was a significant leakage and drained out all the water through the filling loop, I got 0 BA. Then we found no leakage - we topped up - the pressure started rising immediately from 1.0 and not 0 as was expected.

Please help to analyse, any advice is welcome. I do not know what to do

 

[gmartine]

When you can, over pressurise the system say to 2 bar without turning the system on and see if the condensate is leaking, you may have a cracked/faulty heat exhanger.

 

[ArtemPtushkin]

thank you, good tip, I will try

 

[ArtemPtushkin]

When you can, over pressurise the system say to 2 bar without turning the system on and see if the condensate is leaking, you may have a cracked/faulty heat exhanger.

thank you, good tip, I will try