How each works
A storage heater keeps its whole volume hot day and night, typically 40 to 60 gallons in a home. Drawing from it lets cold water in at the bottom, which the flame or elements then bring back up. An on-demand unit stores nothing; opening a tap trips a flow switch, the burner lights, and water picks up heat while crossing the exchanger.
Side by side
| Factor | Tank | Tankless |
|---|---|---|
| Up-front cost | Lower | Steeper, especially where the gas piping needs enlarging |
| Hot water supply | Limited by tank size and recovery | Continuous, limited by flow rate |
| Standby heat loss | Yes | None |
| Space | Floor space | Wall-mounted |
| Maintenance | Occasional flushing, anode checks | Annual descaling in hard water |
| Lifespan | Often around a decade | Often longer with maintenance |
Who suits a tank
Smaller households, homes where the existing venting and gas line suit a tank, and owners who want the lowest purchase price.
Who suits tankless
Larger families, homes with a soaker tub, and owners planning to stay long enough for efficiency gains to matter. Tankless is also handy where floor space is tight.
Renting versus owning
Many Ontario homes rent their water heater. Renting spreads the cost and includes repairs, but over many years it can cost more than owning. Read the rental agreement carefully, including buyout and removal terms.
See tankless installation, gas tank replacement and electric tank installation.