If a cast-iron boiler is significantly oversized and experiences long off-times between firing cycles, much of the heat stored in the boiler's thermal mass can be carried up the flue by air currents passing through the combustion chamber.

Question

Quizplus · Accepted Answer

This is true because the oversized boiler will have a larger thermal mass than necessary, resulting in longer cycles and extended periods of no firing. As a result, the heat stored in the thermal mass will have more time to dissipate into the combustion chamber and eventually up the flue.

If a Cast-Iron Boiler Is Significantly Oversized and Experiences Long