How large should the grill be for two hot water boilers and two water heaters firing at the specified BTUH in a contained room?

The correct answer indicates a grill size of 250 square inches for the room containing two hot water boilers and two water heaters. This size is determined by the total BTUH (British Thermal Units per Hour) output of the equipment, as adequate ventilation is essential for safe operation.

In spaces where appliances like water heaters and boilers are installed, proper ventilation is necessary to ensure that combustion gases can dissipate and to provide enough fresh air for combustion. The general rule of thumb is that the upfront square inches of the grill should be proportional to the BTUH rating of the gas-fired appliances. Calculating this helps to maintain a safe and efficient operation, preventing the buildup of carbon monoxide and ensuring adequate oxygen for combustion.

In many cases, local codes or manufacturer specifications may provide specific ventilation requirements based on the type of fuel used and the configuration of the room. A grill size of 250 square inches is a standard that generally meets the necessary airflow requirements for the scenario posed in this question, reflecting both safety compliance and operational efficiency for the specific appliances mentioned.