The size tank needed to fill a propane fireplace depends on usage and how many times a year you are willing to have it filled. Determine usage by taking into account your surroundings and your own preferences. In addition, determine if you are going to use the propane tank for your fireplace alone or other appliances as well. It is also important to consider that you can only fill a propane tank to 80% capacity in order to leave room for vapors. This is necessary because it relieves pressure in the tank.
Warm and Cold
The more you use the fireplace, such as in colder areas, the bigger the better. On the contrary, the less you use the propane fireplace, such as in warmer climates, a smaller version will work.
Number of Appliances
A 100 gallon tank is average for heating only one appliance. The more appliances you are heating, the bigger the tank should be. For multiple appliances in a warmer area, a 500 gallon tank that is filled once a year is normal. For multiple appliances in colder areas, 1000 gallon tanks filling it three times or less per year is also typical.
Filling the Tank
With a tank that is not big enough, you will be filling it more often than not. Filling a tank should only happen one to four times a year. Again, this number is also substantially affected by how much you use your tank.