Final answer:
The maximum BTU rating for an unvented room heater varies by local codes. A 40,000 BTU/hr heater outputs approximately 11,720 watts. Heater efficiency and required capacity depend on a building's insulation and the climate.
Step-by-step explanation:
The maximum BTU rating of a room heater allowed in a public building that is not required to be vented is a specific regulation that can vary by region and is based on safety standards. Generally, unvented heaters have lower BTU ratings due to the potential safety risks from combustion byproducts. For an accurate answer, it would be necessary to consult local building codes or a heating specialist.
For the given examples relating to power output, a water heater with a rating of 40,000 BTU/hr is capable of putting out approximately 11,720 watts (W). This is calculated using the conversion that 1 BTU/hr is equal to 0.293 W. Thus, to convert BTUs to watts, we multiply the BTU rating by 0.293. For example, a heater rated at 30,000 BTU/hr is effectively about 8,800 W, which is nearly equivalent to 10 kW.
The ability of a heater to maintain a temperature difference (ΔT) in a house depends on the thermal characteristics of the house and the power of the heater. A 10 kW heater, which is roughly 30,000 BTU/hr, could potentially maintain high ΔT's depending on the house's insulation. Nevertheless, in colder climates, houses either need to have better insulation or larger heaters to maintain comfortable temperatures without incurring excessive heating costs.