Tankless vs Tank Water Heater in Calgary: Which Fits Your Home?

How do tankless and tank water heaters differ?

A storage tank heater keeps a tank of heated water ready. Natural Resources Canada describes it as the most commonly installed type in Canadian homes: a thermostat turns on the burner or element to keep the stored water at temperature, and cold water flows in to replace what you use.

A tankless (or on-demand) heater has no storage tank. It heats flowing water with either an electric element or a gas burner. NRCan notes it heats water only when needed, which removes the constant standby heat loss a tank has.

Tank types in Calgary homes. Our hot water tank page lists traditional, power vent, direct vent and tankless units. NRCan explains the venting differences:

• Conventional gas tanks use house air for combustion and vent through a chimney or vent.
• Power-vented tanks use a fan to push exhaust out a side wall and need electricity, so they cannot produce hot water in a power outage.
• Direct-vent (sealed combustion) tanks draw combustion air from outside and vent through the wall, and are more resistant to combustion spillage than conventional tanks.

Tankless vs tank: how do they compare?

We are not quoting installed prices for either type here. Our hot water tank page gives a range of $900 to $2,000+ for tank installation in Calgary, depending on size, type and complexity, and says a clear quote comes before work starts. We do not have a sourced Calgary price for tankless, so get a written quote that spells out gas and venting work. Our guide on what a hot water tank costs in Calgary goes through the price drivers.

Is tankless more efficient?

On average, yes. Natural Resources Canada’s ENERGY STAR page says certified tankless heaters use 30% less energy, on average, than a storage tank type. Its older Water Heater Guide (a 2012 revision) puts numbers on the efficiency rating (the energy factor, or EF): gas-fired tankless heaters rated from 0.64 to 0.98, averaging 0.85, against 0.53 to 0.70, averaging 0.62, for gas-fired storage tanks, based on September 2011 listings.

Two caveats. First, those are averages from a guide that is over a decade old, so check current ratings for any model you consider. Second, efficiency is not the same as savings in your house. NRCan makes the point that every appliance has two price tags: the purchase price and the operating cost. Its example is an electric tank where energy costs over 10 years run about seven times the equipment cost. The lesson is to compare operating cost along with price, using your own household’s hot water use.

Does a tankless heater really give endless hot water?

Not unlimited. NRCan’s ENERGY STAR page says a tankless unit can provide essentially endless hot water, because it heats as it flows. But the Water Heater Guide is clear about the limit: output is a flow rate, not a volume.

• Peak demand. If more than one shower or an appliance such as a dishwasher runs at once, those demands must be added and the unit must meet the peak.
• Cold incoming water. NRCan’s example: a unit that can deliver 15 litres per minute at an 18 degrees C inlet in summer delivers only about 11 litres per minute with a 5 degrees C inlet. The guide says winter intake water may be as cold as 5 degrees C, so choose with that in mind.
• Electric limits. Most electric on-demand heaters cannot supply an entire house, so they are rarely used that way in Canada.

For tank-based sizing, see our walk-through on what size hot water tank you need. NRCan’s own advice for tankless is to consult an experienced plumber to estimate your home’s hot water demands.

What does a tankless swap involve in an existing Calgary home?

This is where tankless decisions are usually won or lost. The heater is only part of the job.

Gas supply. NRCan’s guide says replacing a conventional tank with a gas tankless heater may require the gas supply to be increased, and gives a typical example of a 3/4-inch supply for a tankless unit compared with a 1/2-inch supply for a standard water heater. Sizing a gas line is licensed work, and we are not suggesting a size for your house.

Venting. The guide says gas-fired on-demand heaters are usually mounted on an outside wall so that flue gases can be vented through a side wall, and that building and combustion safety codes restrict where sidewall vents can go. It also says an evaluation by qualified service personnel is required when adding, removing or replacing any gas-fired equipment.

Permits. The City of Calgary says that in some cases replacing a hot water tank may require a permit, for example when changes involve upstream gas lines, the venting system or the type of water heater. Switching from tank to tankless can be all three. Our page on the topic is does Calgary require a permit to replace a hot water tank.

Hard water. The City describes Calgary’s water as hard because of calcium and magnesium, with 2025 hardness of 141 to 274 mg/L depending on supply and season. Rheem says mineral scale can build up inside a tankless unit’s heat exchanger, reducing heating efficiency and increasing wear, and that in hard-water areas you should plan to flush or descale about every six months. Natural Resources Canada more generally recommends servicing a tankless unit once every year or two by a qualified professional. Plan for descaling as a standing maintenance cost.

What are the honest drawbacks of tankless?

• Higher upfront cost. Our page says tankless costs more upfront.
• More installation work. A bigger gas line, side-wall venting and permits can add to the job.
• Electricity dependence. NRCan notes gas models that need electricity to operate cannot provide hot water in a power outage. Ask about your model.
• Maintenance. Descaling is more than a nice-to-have in a hard-water city.
• Capacity limits. Peak demand and cold winter inlet water can cut delivery below the number on the box.

What are the honest drawbacks of a tank?

• Standby heat loss. A tank keeps stored water hot all day, which NRCan identifies as the cost tankless eliminates.
• Shorter life. Rheem’s tank range is shorter than its tankless range.
• Running out. A tank holds a finite amount. NRCan advises judging capacity by first hour rating rather than tank size alone.
• Corrosion. The anode rod wears, and the tank rusts once it is gone. The details are in how long a hot water tank lasts.
• Floor space. The unit stands in your utility room.

Which one should you choose?

There is no universal winner, and the most useful framing is a set of situations, which are our own reasoning from the sources above rather than advice for your house.

• A tank tends to fit when your budget is the priority, your gas supply and venting suit it, and your household’s hot water use is moderate and predictable. Our page describes traditional tanks as lower cost and simpler to maintain.
• Tankless tends to fit when you value continuous hot water and lower energy use, have or can add the gas supply and venting, and will keep up with descaling. Our page describes tankless units as providing endless hot water and being more energy efficient.
• Neither is a good answer if nobody has checked your existing gas line, venting and permit requirements. Get that assessed first.

As our hot water tank page puts it, “We’ll help you choose based on your household size and budget.”

What three questions should you ask any installer?

1. What will the gas line and venting work involve, and is it in the quote? A tankless swap can change both.
2. What permits does this need, and who pulls them? Gas permits must be pulled by a licensed contractor unless the owner is a first- or second-class gasfitter, and the City says some replacements need a plumbing permit.
3. What maintenance will this need in Calgary’s hard water, and what does it cost? Ask for descaling frequency, or anode and flushing needs for a tank, in writing.

Next step

If you are weighing the two, ask a licensed plumber to look at your gas line, venting and hot water habits before you pick a unit. H2O Expert Plumbing installs traditional, power vent, direct vent and tankless units through our hot water tank installation and repair in Calgary service, and gas line hook-ups are listed among our plumbing, gas and heating services. We are available 7 days a week. Get a free quote or call +1 (403) 700-4443. You can also read about our licensed Calgary plumbers.