Tankless vs. Tank Water Heaters

Tankless vs. Tank Water Heaters

One of the common questions I get during an inspection is: "what exactly is a tankless water heater?"

After I give my answer, another question inevitably follows: "should I get one?"

It isn't my position to tell people whether or not to make such a purchase, but I am always happy to explain the differencess:

We are all pretty familiar with the traditional tank or storage water heater. The water heating system is installed in a special insulated tank. Cold water is supplied to the tank through an inlet pipe and is heated according to the set temperature. The heated water is stored in the same tank until it is withdrawn. In case of a tankless water heater, there is no storage of hot water. The cold water is heated directly after passing heating coils installed in the unit.

As hot water is heated and stored constantly in the tank water heater, energy consumption is high. In tank water heater, cold water is supplied in the tank as soon as hot water is drawn off. Thus, the reservoir is always full with hot water, even if it is not required. This wasted energy is called standby heat loss.

As the amount of hot water availability in a tank water heater depends on the size of the reservoir, there are chances of insufficient or excess hot water.

Tank water heaters are available with fuel types - electric, natural gas and liquid propane.

Tankless Heaters

A tankless water heater doesn't store water, but produces hot water on-demand. They come in  electricity and gas (including propane and kerosene) models.

The conventional tank water heater heats the water, stores it... and after a while, repeats the cycle as the water cools down.

This means you are using (and paying for) a lot of wasted energy.

So the main advantage of a tankless water heater is that it has no storage tank. It isn't on until water flows through it. But the moment water flows through it, the water triggers off a mechanism that turns on either the electricity or flow of gas which is ignited automatically. Water runs through a series of specially designed tubes (mostly high grade copper) that heat the water to very high temperatures instantly.

Water goes into the unit cold and in a matter of seconds begins flowing out hot.