Is an On-Demand Water Heater Safer Than a Traditional Storage Tank Water Heater?

On-demand water heaters—also known as tankless heaters—provide certain advantages over the traditional storage tank models. Because a tankless unit produces hot water only when it’s actually needed, no water is stored between uses. Heat loss from the tank is therefore not a factor, nor is the extra energy consumption required to repeatedly re-heat water in the tank. This usually means lower operating costs.

But what about their safety? It’s important to note that safety is largely a function of proper installation by a qualified professional and regular maintenance. Neither type of water heater is inherently dangerous; both are engineered and certified for safety and meet building codes. Here are a few comparisons between on-demand water heaters and traditional storage tank heaters.

  • Combustion fumes. Both storage tank and tankless models produce toxic combustion gases that must be properly vented, including carbon monoxide. Because hot gases rise naturally, a traditional storage tank heater passively vents upward through the roof. However, a tankless heater is typically installed horizontally, so the vent pipe often extends through an exterior wall instead of the roof. Therefore, tankless models usually incorporate an electric exhaust fan to safely force fumes outside. With proper installation and recommended preventive maintenance to ensure proper venting, the safety factor between the two units is approximately equal.
  • Water damage potential. The tank utilized in a conventional water heater is subject to corrosion. Most storage tank water heaters begin leaking before they are 10 years old. If the tank ruptures completely—a not uncommon event—severe water damage (as well as resultant toxic mold contamination) may occur as water from the tank and inlet pipe flood the house. Because an on-demand water heater does not utilize a storage tank, damage associated with tank rupture is eliminated.
  • Fire hazard. Older storage tank models typically utilized a pilot light to ignite the main burner. This continuous open flame could present a hazard in certain unusual circumstances. Today, newer tank water heaters incorporate electronic ignition. Similarly, most new tankless heaters also incorporate an electric igniter and do not utilize an open flame pilot light.

Tags: , ,

Return to the Blog Home Page