If you have an 80% furnace in a basement running 60,000 BTU/h, what is the minimum space needed so that it is not considered a confined space?
A. 3000 ft3
B. 3000 ft2
C. 3000 ft
D. 5000 ft3
E. 1000 ft3
Answer (2)
Determine the furnace's BTU/h rating, which is 60,000 BTU/h.
Use the IFGC standard of 50 cubic feet per 1,000 BTU/h to calculate the minimum space.
Calculate the minimum volume: M inim u m V o l u m e = 1 , 000 BT U / h /50 f t 3 60 , 000 BT U / h = 3000 f t 3 .
The minimum space needed is 3000 f t 3 .
Explanation
Understanding the Problem We need to determine the minimum space required for a furnace with an 80% efficiency rating and a 60,000 BTU/h input rate, so it is not considered a confined space. According to the International Fuel Gas Code (IFGC), a confined space is defined as a space whose volume is less than 50 cubic feet per 1,000 BTU/h input rate.
Setting up the Calculation To find the minimum required volume, we use the formula:
Minimum Volume (ft3) = (Furnace BTU/h) / (BTU/h per ft3)
We know the furnace BTU/h is 60,000, and the confined space limit is 1,000 BTU/h per 50 ft3.
Calculating Minimum Volume Now, we calculate the minimum volume:
Minimum Volume (ft3) = (60,000 BTU/h) / (1,000 BTU/h / 50 ft3)
Minimum Volume (ft3) = 60,000 / (1,000/50)
Minimum Volume (ft3) = 60,000 / 20
Minimum Volume (ft3) = 3000 ft3
Final Answer The minimum space needed for the furnace not to be considered a confined space is 3000 ft3.
Examples
Understanding the minimum space requirements for furnaces is crucial in ensuring safe and efficient operation. For instance, in designing a new home or renovating an existing one, architects and HVAC technicians must calculate the appropriate room size to accommodate the furnace. This calculation prevents the accumulation of combustible gases and ensures adequate airflow for combustion, thereby reducing the risk of carbon monoxide poisoning and improving the furnace's energy efficiency. This also applies to other appliances like water heaters and boilers, where similar space and ventilation considerations are necessary to maintain safety and performance.
The minimum space required for an 80% furnace rated at 60,000 BTU/h to avoid being classified as a confined space is 3000 ft³. This calculation is based on the International Fuel Gas Code standards. Proper ventilation space is essential for safety and efficiency.
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