Leakage will probably occur at connections with piping or at places where an instrument is (like Pt100...) fixed into a boiler.Buy a large chocolate, give it to children and keep the thin aluminium foil. Bend it around the connector (flange...) to form a small chamber and put your leak detector in it. The chamber will increase local concentration of the leak and it is easily removable. Your charm and your technicall skills will be appreciated.
m777182