Which type of appliance has a combustion chamber that is sealed from the area it is located in?

A sealed combustion appliance features a combustion chamber that is isolated from the surrounding area, which allows it to draw in combustion air directly from the outside and exhaust the combustion gases outside as well. This setup helps to improve the efficiency of the appliance and enhances safety by preventing the backdraft of harmful gases into the living space. Additionally, because it is not venting air from inside the building, it maintains indoor air quality and reduces the potential for creating negative pressure conditions that can affect other appliances or systems within the home.

In contrast, open combustion appliances rely on indoor air for combustion and can create safety hazards if there are issues with ventilation. Induced draft appliances use mechanical means to expel combustion gases but may still rely on indoor air for combustion, not providing the same level of isolation found in sealed combustion appliances. Class B refers to a type of venting system used but does not specifically describe the combustion chamber's isolation from the interior environment. Sealed combustion is distinct in its design and operational advantages.