Which type of heaters should NOT be installed in or attached to combustible walls unless they are listed for such installation?

Wall-type room heaters should not be installed in or attached to combustible walls unless they are specifically listed for such installation due to the potential fire hazard they can pose. These heaters generate significant heat, and if they are placed against or near combustible materials without proper listing for this type of installation, it could lead to these materials igniting.

When it comes to safe installation practices, equipment that is designed to be attached to walls must adhere to codes and standards which take into account the heat output and the clearance required from combustible materials. This ensures that any heat generated does not compromise the integrity of surrounding materials. Only heaters specifically rated for installation against combustible surfaces have undergone testing to confirm that they can maintain safe operating temperatures under those conditions.

In contrast, portable heaters, ceiling-mounted heaters, and baseboard heaters each have different installation requirements and may be designed for more versatile placement, which often includes being installed in proximity to combustible materials under certain conditions. It is crucial to always adhere to manufacturer specifications and local codes to ensure safety during installation.