Recently noticed a gas smell coming from my ideal classic RS50 boiler. Cadent have been out and confirmed a small leak and capped off the gas. The question I have though is that the gas smell only appears when the boiler fires up not when the pilot is burning normally. Gas smell continues as boiler burns higher. Any advice on what it could be? I thought it may be a faulty gas valve. Engineer is coming out tomorrow but I’m just curious as to what people think.