What is permitted to be installed between a boiler and safety devices?

The correct choice is that nothing is permitted to be installed between a boiler and safety devices. This reflects a critical safety principle in boiler operation. Safety devices, such as pressure relief valves and low water cut-off switches, are designed to operate in real time based on the conditions within the boiler.

If any valves, filters, or pipes are installed between the boiler and these devices, they could potentially hinder the safety devices’ operation. For example, a valve could be accidentally closed, or a filter could become clogged, preventing the safety device from receiving the necessary signals to function properly. Therefore, maintaining a direct connection is essential to ensuring the reliable operation of these safety features, thus enhancing the overall safety of the boiler system.

In this context, the options of valves, pipes, or filters all introduce a risk that could compromise the responsiveness and effectiveness of the safety devices, making it crucial to leave that space clear.