Aquatherm piping systems do not produce toxic by-products during combustion. In a fully developed fire, Fusiolen® PP-R will only produce CO2 and H2Ogas. In an under-developed fire trace amounts of CO can be produced, but this is common in all combustible materials such as wood and paper.

Many building codes do not consider the toxicity of the smoke produced but focus only on the volume and opacity of the smoke. Therefore, it is important to install only pipe that meets local code requirements. These codes generally reference ASTM E84 in the United States and CAN/ULC S-102.2 in Canada and require that the installed pipe have a Flame Spread Index of 25 or less and Smoke Development Index of 50 or less.

Bare Aquatherm pipes have the following ratings:
Flame Spread Index: 30
Smoke Development Index: 100

A compatible insulation material can be used to meet flame spread and smoke development requirements.