Thermal Numeracy

Thermal numeracy refers to understanding the quantities of heat produced, emitted, and transferred in various physical phenomena.

• BTU - 1 lb water raise by 1 degree F
• BTU of wood is 8k-9k per lb -[1]
• U value of insulation is BTU/(hr*sq ft*deg F). It is the inverse of R value - [2]
• Fireplace heat loss from chimney can be 80-90% - [3]
• At high temperatures, temperature in degrees F is about 2x that of degrees C. Specifically, ~9/5 times.
• Glenwood 5000 stove is rated for 100k BTU, with 11 sf of heat exchange area - about 10k BTU/SF
• 1 kW ~ 3000 BTU/hr
• Black pipe is only $12/square foot (10k BTU) of heat exchange area using 1" pipe! - [4]
• 1/2" PEX power production - 22 BTU/hr for 1 foot of length - [5]. 500 feet per trough = 11k BTU
• Cord of wood is $235, and 4000 lb - [6]
• Thermal expansion coefficient of water is 1/10000 for F - [7]