Is this an insert into a previous wood burning fireplace? Direct vent or vent free? BTUs?
Too broad a question. Need BTUs of heater + how many hours running per day to answer.
ABOUT 875 BTUs a month, or 6.4 CCF per month
One measure does not directly translate to another. A BTU is the amount of heat that it takes to raise the temp of one pound of water by one degree F. A burning match, and a burning fireplace may both be at 650 degrees, but the fireplace gives off more heat (more BTUs)
4800 BTUs will 150 square feet.
A small room is about 5,000 BTUs. Most people don't have a room that would require more than 10,000 BTUs.
90,000 BTUs - the 090 is what tells you the BTUs of the unit.
5,000
A 100 pound propane tank has a capacity of 2,160,509 BTUs
6,520 Btus
The answer depends on the city. Somewhere like Colombo (Sri Lanka) will probably require 0 btus.
A romm 20x9 is 180 square feet. You will need 5000 to 6000 BTUs for this.