Tank-less or On Demand Hot Water Heaters are becoming more and more popular in North America on a daily basis. They are a relatively new product here, but in other parts of the world, they have been in use for decades. Like any technology that differs from the norm, On Demand units pose both advantages and disadvantages. Here are a few considerations:
On the “Good” side of the ledger, tank-less water heaters heat cold water with electricity or natural gas only as it is “demanded”, that means that there is no hot water being stored at any time. Heating water and storing it for future use is by definition wasteful.
They are considerably more efficient than conventional hot water tanks – at least 20-30 percent in fact.
Unlike a hot water tank which needs to re-heat the water once it’s been used up, the hot water from a tankless unit is virtually endless. Want to take a 5-hour hot shower, go ahead.
They are reasonably compact, allowing for far greater flexibility on installation. As they can be wall mounted, only a small space in an existing room is required.
On the “Bad” side, On Demand hot water heaters have limitations as to the amount of water flow allowed. Depending on the size of the unit, one may find that they can only operate two hot water outlets at a time, for example. In some cases, people install more than one unit as per their needs.
The amount of energy input required, be it natural gas or electricity may be greater than that currently available to the home. This is something that should always be determined before deciding on this technology.
Not as common a problem with newer models, but there are some natural gas-fired tankless systems which employ a constant burning pilot light, which can be wasteful.
The initial price is considerably higher than a conventional hot water heater (tank). It’s an excellent idea to calculate the energy savings over the long term to be able to determine the overall “payoff” from using a tankless system.