Finally, hoped Karel Belčamin, the C5s had a boiler that provided them with enough steam. And so it was. In the event, the boiler used on the C5A was not a success, although the in the days before superheating, the twin domes worked quite well in keeping the steam as dry as possible and preventing priming. The C5B had a single dome and thus lent itself admirably to superheating, which was applied from 1907 onwards, the only change in the engines' appearance being the removal of the Crampton steam pipe. At the same time as fitting a new boiler, Belčamin carried out various experiments with the balancing, a perennial difficulty with tandem compounds. None of this work brought much benefit and the problem remained unsolved. In later years, the engines were relegated to secondary duties, where speeds were lower and the reciprocating masses less troublesome. Nonetheless, a few were rebuilt again in 1912 as class C5C. The last C5B was withdrawn in 1937.