How Does Altitude Affect the Performance of Propane Water Heaters?

Altitude and Atmospheric Pressure

At higher altitudes, atmospheric pressure decreases, resulting in lower water flow rates in propane water heaters. This is because the pressure drop across the flow control valve increases with altitude, reducing the flow rate. For every 1,000-foot increase in altitude, the atmospheric pressure decreases by approximately 0.55 psi, which can lead to a 5-10% decrease in water flow rate.

Sizing and Venting Considerations

When sizing a propane tankless water heater for high-altitude applications, it’s essential to consider the reduced water flow rates and increased pressure drop. This may require a larger water heater or a more powerful burner to maintain adequate flow rates. Additionally, venting systems may need to be designed to accommodate the increased pressure drop, which can be achieved by using larger vent pipes or more powerful blowers.

Freeze Protection and Demand Sizing

In high-altitude areas, freeze protection and demand sizing become critical considerations for propane water heaters. To prevent freezing, it’s essential to install freeze-protected piping and to ensure that the water heater is sized to meet the peak demand of the household. For example, in areas with frequent temperature fluctuations, a propane tankless water heater with a built-in freeze protection system or a separate freeze protection device may be necessary to prevent damage to the unit.