How Long Does a 20-Pound Propane Tank Last on a Buddy Heater?

Propane is a widely used fuel especially for off-grid heating needs. Understanding how long a 20-pound propane tank lasts on a buddy heater is important for planning and conservation purposes. Let's dive into the details.

Understanding BTUs and Propane Storage

Propane's heating value is approximately 22,000 British Thermal Units (BTUs) per pound. A 20-pound propane tank, therefore, contains about 440,000 BTUs.

Calculating the Duration at Different Settings

The duration a propane tank lasts can vary based on the heater's setting. For a buddy heater:

Standard Setting

A buddy heater with a low setting of 4,000 BTU/hour can run for about 100 hours (4 days) on a fully charged 20-pound tank. If the tank is only partially filled (15 pounds), the duration will be shorter.

High Setting

A high setting of 9,000 BTU/hour will allow the heater to function for approximately 44 hours (about 2 days) on a full 20-pound tank.

General Propane Consumption Calculations

For a more detailed understanding, we can use the BTU-to-propane-quantity conversion. Each pound of propane contains approximately 21,500 BTUs.

BTUs and Heater Rating

Heaters are rated in BTUs per hour. A 20-pound tank might typically contain around 17-18 pounds or about 380,000-390,000 BTUs, depending on fill.

Example Calculation (30,000 BTU Heater)

Using a 30,000 BTU heater as an example:

Calculate the duration by dividing the total BTUs in the tank (430,000 BTUs) by the heater's burn rate (30,000 BTUs/hour). Total duration 430,000 BTUs / 30,000 BTUs/hour approximately 14.3 hours.

Real-World Factors

The actual duration a 20-pound propane tank lasts can vary based on several factors:

Heating Space: The volume of the space that needs to be heated directly impacts how long the propane will last. Environmental Conditions: Cold temperatures and the need to maintain warmth increase the consumption rate. Insulation Levels: Proper insulation can significantly extend the duration of propane usage.

Cylinder Volume and BTUs

A 20-pound propane cylinder typically holds about 4.5 gallons of propane. Each gallon of propane contains approximately 90,000 BTUs. Thus, a 20-pound steel cylinder converts to these BTUs:

4.5 gallons * 91,500 BTUs/gallon 411,750 BTUs. Total duration at 30,000 BTUs/hour 411,750 BTUs / 30,000 BTUs/hour approximately 13.7 hours.

Summary

To summarize, the duration a 20-pound propane tank lasts on a buddy heater can range from about 8 to 100 hours, depending on various factors including the setting, the condition of the tank, and environmental conditions. Always refer to the specific heater's BTU rating and consult the manufacturer's guidelines for the best estimates.