The beach or the mountains?
Ford, Chevy, or Ram trucks?
Pick a side and prepare for battle! No matter which side of the tank vs. tankless water heater argument you stand on, you will find plenty of company. In this article we will not define which is better – that choice will be up to you. We will provide you with some unbiased information to allow you to make an informed decision.
Tank style water heaters have been around for an exceptionally long time and have proven to be reliable and durable. They can heat water by way of electric elements or gas burners, or be coupled with solar-heat arrays (very popular in some countries) or even connected to ground-sourced heat pumps and make use of residual heat from the air-conditioning process. Any way the water gets heated, the principle is the same – a tank that stores heated water for future use. Most have relatively few moving parts to break or wear out and can be expected to last for years. In the case of a loss of power you have the benefit of hot water for a while (several hours at least). The downside is their size and weight, which must be accommodated with space – and in the case of attic installation – some stout supporting structure. Gas-fired units require ventilation and some sort of vent stack through the roof. Since they store water, the heating process is on-going to maintain hot water at a certain temperature.
In contrast, the tankless water heater is the Ferrari to the tanker truck (that pun was entirely intended). They are much smaller and lighter, so the placement options in your house are much less limited. They can even be installed outside. Tankless water heaters are essentially small boilers that only come on when hot water is demanded. Then they fire up with high intensity burners to get the water hot as fast as it can flow through the coils. They provide the huge advantage of endless hot water, as compared to the tank which will run out at some point. And since they do not need to maintain temperature on a big tank of water, they (theoretically) should provide energy savings. Yes, tankless water heaters have a downside as well. Generally, for a given household capacity, tankless water heaters are more expensive to install. They also require a vent stack through the roof. They depend on electronic controls and ignition, so a power outage shuts down all hot water immediately. They require more maintenance to retain their efficiency, such as periodic flushing to remove scale deposits. And in the real world the energy cost savings may be negated by longer showers (remember endless hot water?).
Finally, do not confuse endless hot water with “on demand” hot water. When you turn on the hot water faucet at the other end of the house the water still has many feet of pipe to go through before it reaches you.