Many times when a customer wants us to change a water heater out, they install a new water heater that uses the same fuel and exhaust system as the prior unit. Occasionally though, the customer is curious whether they should move to a new water heater system. Their primary concern is usually which one will last longer.
Typically when people ask me how long water heaters last, I usually tell them that 15 years is about my benchmark for being par for the course. We certainly change some out that are 30 to 35 years old, which is very commendable, but also a bit of an abnormality. I typically tell folks that atmospheric gas water heaters last the longest, and they are the style that we most frequently get to those 30 year age ranges. After that, Power vent gas water heaters and instant tankless water heaters probably tied for second at around the 15 year range, and electric water heaters are generally somewhere in between the 15 year and 10 year range. Here are some of the reasons why:
Gas atmospheric water heater (Approx 20 years): this style water of heater is very simplistic. There is a gas control module that regulates the gas going to a burner, which heats the bottom of the water heater tank. Very similar to a boiling pot of water on the stove. Exhaust gases travel up a corridor within the water heater and go out the top. The reason that atmospheric water heaters are called atmospheric water heaters is because they use atmospheric pressure to remove the exhaust gases. The exhaust piping always must travel with some vertical slope, and eventually exhaust out the top of the house. This allows the hot exhaust to rise because it is warmer than the cold air surrounding it. The beauty of this system, and the reason it allows for higher ages, is because it’s very simplistic. There’s very few working parts, which means less can go wrong. This style of water heater is also fairly resilient to poor water quality. Sediment settles at the bottom of the tank, which should be flushed, but does not generally impair function.
Power vent water heaters (Approx 15 years): Power vent water heaters work similarly to the atmospheric water heater, except they have a blower fan on the top of them that forces the exhaust outwards. This allows for horizontal exhaust travel, and we often see the exhaust on a power vent water heater ran in solid core PVC pipe. The reason I dock Power Vent water heaters on the longevity scale, is because of the power vent itself. It has a motor in it that runs fairly frequently and gets subjected to hot exhaust gases and is usually the failure point on a power vent water heater. Typically you can order a new power vent system for your power vent water heater, but they are not very well stocked locally for parts, and cost prohibitive.
On-Demand, a.k.a. Tankless, Water Heaters (approx. 15 years w/ maintenance): These units have been getting increasingly more popular these days with the latest energy conservation movements, and have their own pros/cons. That said, on the topic of longevity, These units require a decent amount of maintenance to extend their life period out into the 15 year range. Tankless units have a heat exchanger inside them that has a knack for building up scale from the impurities in the water, and should be flushed out yearly with vinegar, or a more potent acid. If you're simply hoping to set it and forget it, Tankless water heaters often throw codes and stop working within the first 10 years of their lives.
Electric Water Heater (approx 10 years): These are the cheapest units to install, but generally start to need elements changed out within 10 years of initial installation. These elements are not very expensive, so you can often do this multiple times and get 20+ years out of the water heater, but people need to be aware that issues will come up. The best way to prevent issues with the heating elements, is to flush the unit out. Which we will discuss in a how-to video in the upcoming weeks.
In summary, in the case of lifespan and longevity, I generally recommend the system with the fewest working parts (Atmospheric water heater). However, there are other factors that should go in to the picking of the water heater as well, which were not covered in this article. To discuss which system would be best for your family and application, give us a call!
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