What must a fireplace door comply with if it's not specifically tested for factory-built fireplaces?

A fireplace door that is not specifically tested for factory-built fireplaces must adhere to the requirement that it cannot be gasketed. This is crucial because gasketed doors can create a sealed environment that may lead to the buildup of dangerous gases and fumes, which can create unsafe conditions during operation. Non-gasketed doors allow for some ventilation, reducing the risk of harmful gas accumulation and adhering to safety standards.

In the context of fireplace performance and safety, it is essential that any modifications or additions, like doors, do not interfere with the intended function of the fireplace. Ensuring that the door is not gasketed helps maintain proper airflow, which is vital for combustion and exhaust purposes, making the fireplace safer to use.