Which of the following mechanical installations do not require a permit?

The correct choice indicates that portable heating appliances, portable ventilation appliances, and portable cooling units do not require a permit for installation. This is based on the understanding of the International Residential Code (IRC), which often considers these types of equipment as temporary or easily movable, thus reducing the need for permits that are typically required for more permanent mechanical installations.

Portable appliances are generally defined as those that are not fixed or attached to the structure, allowing for easier relocation. This classification helps to alleviate some of the regulatory burden on homeowners and renters, as these installations pose fewer concerns related to building safety, structural integrity, and long-term utility connections.

In the case of heating, ventilation, and cooling (HVAC) systems, more complex installations, such as central heating or air conditioning systems, typically require permits because they involve extensive modifications to plumbing, electrical, and structural components of the building. However, portable units offer flexibility and mobility, which makes them exempt from such requirements.

Therefore, understanding that portable appliances are designed for quick and simple use, and that they do not necessitate structural changes to the property, culminates in the conclusion that no permit is needed for their installation.