Tank or tankless: choosing a water heater
A tank water heater keeps a reservoir hot all day, while a tankless unit heats water only when a tap opens. Tankless avoids standby heat loss and never runs out in a single draw, but it costs more to install and has a flow limit that cold Canadian groundwater makes more noticeable.
How do tank and tankless water heaters differ?
A storage tank holds a set volume of heated water and reheats it when the temperature drops. The tank sits there losing a little heat through its walls around the clock, which is called standby loss. A tankless heater, also called on-demand, has no reservoir. A burner or electric element fires up when water flows through and stops when the tap closes.
The practical result is that the tank can run short if the household draws more hot water than it holds, then needs time to recover. A tankless unit does not run short, but it can only heat so much water per minute. For the wider picture of system types, see natural gas versus electric heating in Canada.
Which one costs less to run?
On-demand heating usually saves some energy, because there is no standby loss. The saving is larger in a household that uses little hot water and smaller in a busy one, where the tank would be drawn down often anyway. Savings also depend on the fuel and its price, so a gas unit and an electric unit compare differently from one province to the next.
Buying cost runs the other way. Tankless units and their installation typically cost more, and a gas model may need a larger gas line, new venting and a drain for condensate. A tank swap is often a like-for-like job. Ask for written quotes, and see home heating costs in Alberta for how local energy prices change the maths.
Why does Canadian climate matter for tankless?
A tankless heater must lift incoming water to the set temperature. In winter, groundwater and municipal supply can be very cold, so the temperature rise needed is bigger and the flow it can deliver at that rise drops. A unit that handles two showers in summer may struggle with the same load in January.
That is why sizing for the coldest month matters. Installers use the number of fixtures likely to run at once and the incoming water temperature to choose a unit. The same logic applies to storage, as set out in how to size a hot water tank. Hard water leaves scale in the heat exchanger over time, so many tankless owners flush the unit on a schedule.
How long do they last and what is the upkeep?
Tanks commonly last roughly a decade or a bit more, with the anode rod and water quality playing a large part. Tankless units are often rated for longer, but the figure on a brochure assumes regular maintenance. Check the warranty terms for parts and the heat exchanger. Our look at heating system lifespans in Canada puts these numbers in context, and a service contract may cover yearly checks.
Neither option is the only path. A heat pump water heater uses less electricity than a standard electric tank, as covered in heat pump water heaters in Canada.
Quick answers
Is a tankless water heater worth it?
It can be for households that use modest amounts of hot water and want no standby loss, if the upfront cost and any gas or electrical upgrades are acceptable. A written quote shows the extra cost.
Do tankless water heaters work in cold climates?
Yes, if sized for the coldest incoming water. Winter supply is colder, so the unit delivers less flow at the same temperature.
How often does a tankless heater need maintenance?
Many manufacturers recommend periodic flushing, especially in hard-water areas. Follow the schedule in your unit's manual.