She demonstrated the major drawback of steam-powered fire-floats one day in 1917: a fire was discovered at 7:30 a.m. in a transit shed at Avonmouth Dock, and Salamander was called out.

The cost of installing diesel engines in Salamander was investigated, but proved too expensive to be worthwhile, and instead the Brigade ordered two new fire-floats, one for Avonmouth and one for the City Docks.

He responded to orders transmitted from the wheel by the ship's telegraph, and controlled the speed and direction of each engine and watched over the pumps at the fire.

Surviving records show that in her first two years at work Bristol Phoenix II attended major fires at Robbins Ltd., Imperial Saw Mills, Cumberland Road (now part of the Baltic Wharf housing estate) Charles Hill & Sons Ltd.'s shipyard and William Butler's tar distillation works at Crew's Hole, Bristol.

This limitation meant that the fire-float's air-draught (the hull and superstructure above the waterline) was very low, and the helmsman had to lie flat on the deck when navigating some of the bridges.

Shortly after this, in November 1938, one of the most serious peacetime fires in the City Docks broke out, at Samuel Thompson & Sons' malthouse (later known as the MacArthur warehouse) in Gas Ferry Road.

In the following year, Pyronaut embarked upon her busiest period, as the air raids of the Bristol Blitz damaged and destroyed countless warehouses, factories, shops and homes around the Floating Harbour.

Operating alongside two motor-launches fitted with fire-fighting equipment, Pyronaut was constantly manned and working through the worst raids of the war.

A reporter recorded the scene: ‘I find clusters of men soaked to the skin, their eyes red-rimmed with the smoke and fumes, plying their hoses oblivious to the danger that threatened them every minute from above’.

In 1949, a serious fire in wastepaper stacks at St. Anne's Board Mill required the attendance of Pyronaut and many shore appliances, as well as the company’s own motor-launch fire-float.

When Rowe Bros' lead works warehouses on Canons' Marsh caught fire in 1950, Pyronaut pumped water from the City Docks.

In September 1951, the most serious peacetime oil fire to date broke out at Avonmouth Docks, and Pyronaut made the journey down the River Avon to attend; she pumped water continually for two days.

The work was never completed, and she was sold again to a private owner in 1983, who began to fit out the changing room as a saloon, with the intention of using Pyronaut as a working/living craft in the south of Ireland.

Listed as part of the National Historic Fleet,[5] she performs displays during major harbour events as well as operating for trips on some summer weekends.