Well done Sir!!
Re point earlier, why no FGA on an old boiler? I'd have thought that was exactly the type of boiler that had to have a flue gas test.[/
on a new boiler you cant do a visual inspection on flame picture or take burner pressure so you must use FGA to check POC's on an older boiler you can check flame pic and take burner pressure, so the visual inspection and check s that you do confirm if the appliance is safe or not therefore a FGA isnt req'd, some people strip/clean/service an old boiler then use a FGa to confirm everything is ok, to me that means they arent comfortable in doing the checks and interpretating the results, different when you first get a FGA you use it on everything to play with it, same as when you get a new digital gas leak detector, you create a wee leak to test your detector is working