Increasing the temperature of a water heater will result in higher energy consumption, which in turn will lead to increased propane usage. This is because the water heater will need to work harder to maintain the higher temperature, using more energy and propane in the process.
Understanding Water Heater Efficiency Ratings
The technical specifications of a water heater can provide insight into how much propane it uses at different temperatures. Two key metrics to consider are the First-Hour Rating (FHR) and the Energy Factor (EF).
First-Hour Rating (FHR)
The First-Hour Rating (FHR) of a water heater indicates the amount of hot water the heater can deliver in the first hour of use. A water heater with a higher FHR will be able to deliver more hot water over a given period of time, but it will also use more propane to do so.
For example, a water heater with an FHR of 50 gallons per hour will use more propane than a water heater with an FHR of 40 gallons per hour, all else being equal. This is because the higher-FHR heater needs to work harder to maintain the higher hot water output.
Energy Factor (EF)
The Energy Factor (EF) of a water heater is a measure of its overall energy efficiency. A higher EF indicates a more efficient water heater, which means it will use less energy (and therefore less propane) to heat the same amount of water.
However, it’s important to note that a higher EF does not necessarily mean the water heater will use less propane overall. If the water heater is set to a higher temperature, it may still use more propane to maintain that temperature, even if it is more energy-efficient.
Calculating Propane Usage
To determine the exact propane usage of a water heater at different temperatures, you can consult the manufacturer’s specifications or work with a professional HVAC technician. They can provide you with the necessary calculations and recommendations for your specific water heater model.
Some key factors that will influence propane usage include:
- Tank size (in gallons)
- Recovery rate (in gallons per hour)
- Inlet water temperature
- Desired output water temperature
- Propane BTU rating of the water heater
For example, let’s say you have a 50-gallon water heater with a recovery rate of 40 gallons per hour and a propane BTU rating of 40,000 BTU/hr. If the inlet water temperature is 55°F and you want to heat the water to 120°F, the propane usage would be:
Propane usage (gallons per hour) = (40,000 BTU/hr) / (91,500 BTU/gallon of propane) = 0.44 gallons per hour
Now, if you increase the desired output temperature to 140°F, the propane usage would increase to:
Propane usage (gallons per hour) = (40,000 BTU/hr) / (91,500 BTU/gallon of propane) = 0.55 gallons per hour
This represents a 25% increase in propane usage by simply raising the water heater temperature by 20°F.
Recommended Temperature Settings
In general, it is recommended to set the water heater temperature to the minimum necessary to meet your hot water needs. This will help to reduce energy consumption and propane usage, while still providing adequate hot water.
The U.S. Department of Energy recommends setting the water heater temperature to 120°F (49°C) to strike a balance between energy efficiency and hot water availability. This temperature is typically sufficient for most household needs, such as bathing, washing dishes, and laundry.
However, if you have specific hot water requirements, such as for a large household or for certain appliances, you may need to adjust the temperature accordingly. Just keep in mind that higher temperatures will result in increased propane usage.
Conclusion
In summary, increasing the temperature of a water heater will result in higher propane usage due to the increased energy required to maintain the higher temperature. By understanding the technical specifications of your water heater, such as the FHR and EF, and by carefully considering your hot water needs, you can optimize the temperature setting to balance energy efficiency and propane usage.
References:
- Energy.gov: Water Heater Energy Factors and Ratings
- Department of Energy: Water Heater Standards
- American Gas Association: Propane Water Heater Efficiency