The entry in brief
A tank is simpler and cheaper to install. A tankless unit saves space, never runs out mid-shower and uses less energy when idle, but costs more up front and needs regular descaling.
How each works
A tank keeps a set amount of water hot all the time, usually 40 or 50 gallons in a family home. A tankless unit holds no store at all; a strong burner lights as soon as a hot tap opens and warms water on its way through.
Side by side
- Up-front cost: tank lower; tankless higher, especially if the gas line needs upsizing.
- Space: tank takes floor space; tankless hangs on a wall.
- Hot water supply: tank can run out; tankless continues but has a flow limit.
- Maintenance: tank needs occasional flushing; tankless needs regular descaling.
- Lifespan: tanks often ten to fifteen years; tankless often longer with care.
Who tends to choose which
Households with many people showering in a row often like tankless. Smaller households, or owners planning to sell in a few years, often find a good tank the sensible choice. Rental agreements also matter: many Ontario homes rent their heaters, and switching may involve buyout terms.
Questions to bring to a plumber
Ask about gas line size, vent routing, condensate drainage and the flow rate you need. Our pages on tankless installation and gas tank replacement explain what each job involves.
What callers want to know
Will a tankless unit always cost less to run?
It usually uses less energy, but savings depend on how much hot water you use and the unit's efficiency.
Can a tankless heater serve a basement apartment too?
A large unit can, if sized for both households' peak use.