Gas Boiler Losing Pressure Increasingly Often

[Nsar1]

Hi all, I have a student house where over the last 12 months the boiler (Vokera) has been losing pressure more and more often. A plumber has said it might be the heat exchanger but he would need the boiler to go cold to check, which is tricky with 6 students coming and going. It strikes me that if the water was leaking there and evaporating from inside the cabinet, it might be obvious as the boiler is in a tiny understairs cupboard?
We thought we might have uncovered the problem when taking a stud wall down revealed a nail through a rad pipe but still problem persists.
Have treated system with pipe sealant but still problem persists. I'm dreading it being a leak under the ground floor, but the drop in pressure seems random but it is definitely getting worse bit by bit. Thoughts welcome, thanks.

 

[SimonG]

Need to isolate boiler from system first to see if its boiler or system that's causing the issue.

Then go from there.

 

[Nsar1]

Understood, thanks for the reply.

 

[oilman]

Hi another reason why systems lose pressure is corrosion.
there are steel radiators and copper pipes and brass valves each element if refer back to the periodic table has a different configuration of electrons so voltages occur inside the heating system between metals. This electrical imbalance drags metal from the iron in the radiators to form iron oxide using the oxygen of the circulating water (H2O) releasing the gas hydrogen ( referred to as "air" in the radiators. The gas can be compressed so allowing a reduction in pressure. As the corrosion continues the pressure continues to fall. First shot get a can of Fernox injectable and add it to your filing loop. Fernox bridges the corrosive borders and thus reduces corrosion. You may also have noticed you have to keep bleeding the radiators.

 

[Nsar1]

Thanks for your reply. Forgive my ignorance but would the pipe sealant (don't know what the brand was or exact product) that has been used do the same job as the Fernox?