# How Long Can a Propane Tank Run a Heater?

A 20-pound propane tank, which contains approximately 430,000 BTUs of liquid propane, can heat a 1,000 square-foot space for more than 10 hours when used in a heater with a heat output of around 42,500 BTUs per hour. However, the actual runtime can vary depending on factors such as the outside temperature, the size and setting of the heater, and the insulation of the space.

## Understanding Propane Tank Capacity and Heater BTU Output

Propane tanks come in various sizes, with the most common being 1-pound, 5-pound, 10-pound, and 20-pound tanks. The amount of propane in a tank is measured in pounds, and each pound of propane contains approximately 21,500 BTUs of energy.

• A 1-pound propane tank contains approximately 21,500 BTUs of propane.
• A 5-pound propane tank contains approximately 107,500 BTUs of propane.
• A 10-pound propane tank contains approximately 215,000 BTUs of propane.
• A 20-pound propane tank contains approximately 430,000 BTUs of propane.

The BTU output of a heater is the measure of the amount of heat it can produce per hour. Typical heater BTU outputs range from 15,000 BTUs to 60,000 BTUs per hour. The higher the BTU output, the more heat the heater can produce, but the faster it will consume the propane in the tank.

## Calculating Heater Runtime on a Propane Tank

To calculate the runtime of a heater on a propane tank, you need to know the following:

1. The size of the propane tank (in pounds)
2. The BTU output of the heater (in BTUs per hour)

The formula to calculate the runtime is:

``````Runtime (in hours) = Propane Tank Capacity (in BTUs) / Heater BTU Output (in BTUs per hour)
``````

For example, let’s say you have a 20-pound propane tank and a heater with a 42,500 BTU output per hour. The runtime would be:

``````Runtime = 430,000 BTUs / 42,500 BTUs per hour = 10.12 hours
``````

This means that the 20-pound propane tank can run the 42,500 BTU heater for over 10 hours.

## Factors Affecting Heater Runtime

While the formula above provides a general estimate, the actual runtime of a heater on a propane tank can vary based on several factors:

1. Outside Temperature: Colder outside temperatures will require the heater to work harder, consuming more propane per hour.
2. Heater Size and Setting: Larger heaters with higher BTU outputs will consume propane faster than smaller heaters. Additionally, running the heater on a higher setting will also increase propane consumption.
3. Space Insulation: Well-insulated spaces will require less heat to maintain the desired temperature, allowing the propane to last longer.
4. Heater Efficiency: Some heaters are more efficient than others, meaning they can produce more heat per unit of propane consumed.

## Heating Outdoor Spaces with Propane

Heating outdoor spaces, such as patios or decks, presents additional challenges due to the open nature of the space. Outdoor heaters typically have higher BTU outputs, ranging from 30,000 BTUs to 60,000 BTUs per hour.

A 20-pound propane tank can provide upwards of 10 hours of heat on the highest setting for a 40,000 BTU patio heater. However, the runtime may be shorter in windy or cold conditions, as the heater will need to work harder to maintain the desired temperature.

## Conclusion

In summary, a 20-pound propane tank can heat a 1,000 square-foot space for more than 10 hours when used with a 42,500 BTU heater. However, the actual runtime can vary significantly based on factors such as outside temperature, heater size and setting, space insulation, and heater efficiency. By understanding these factors, you can better estimate the runtime of your propane heater and ensure you have enough fuel to keep your space warm.