Quick Answer: A tankless water heater heats water only when you open a tap, so it never runs out within its flow limit, takes less space, and uses less energy. The trade-offs are a higher upfront cost, gas line, venting and electrical requirements, a flow-rate limit, and yearly descaling in Calgary’s hard water.
If your hot water tank is aging, or you are planning a renovation, a tankless water heater is probably on your shortlist. The headline promises are endless hot water, lower energy bills, and a unit about the size of a suitcase. Some of that is true, and some of it depends on your house.
This guide covers what a tankless water heater is, the real benefits of tankless water heaters and their drawbacks, and what changes in Calgary specifically: cold winter incoming water, hard water, and older gas lines. By the end you will know whether tankless suits your home or whether a tank is the better call.
What Is a Tankless Water Heater?
A tankless water heater, also called an on-demand or instantaneous water heater, has no storage tank. When you open a hot tap, cold water flows through the unit, where a gas burner or an electric element heats it as it passes through. When you close the tap, the unit shuts off.
A traditional tank heater does the opposite: it keeps 150 to 270 litres of water hot around the clock, whether you use it or not. That difference explains almost every advantage and disadvantage below.
Advantages of Tankless Water Heaters
Hot Water That Doesn’t Run Out
Because the water is heated as it flows, you will not drain a tank of hot water during a long shower or a laundry day. The limit is flow rate, not storage. A properly sized unit delivers a steady supply to the fixtures you run at once, which is a real relief in a busy household.
Lower Energy Use
Natural Resources Canada says an ENERGY STAR certified tankless water heater uses about 30% less energy on average than a storage tank type. The savings come from eliminating standby heat loss, the energy a tank spends keeping water hot while you sleep or are away. Savings vary: households that use less hot water generally see a bigger percentage saving than very high-use households.
A Longer Service Life
Tankless units are commonly quoted at 15 to 20 years or more with regular maintenance, compared with roughly 10 to 15 years for a tank. Lifespan depends heavily on the model and on how well scale is controlled, which matters in Calgary (more on that below).
A Smaller Footprint
A wall-mounted unit frees up floor space in a utility room, closet, or basement. If you are finishing a basement or tight on mechanical room space, that can be a deciding factor.
No Storage Tank to Fail
An old tank that corrodes can release dozens of litres of water onto your floor. With no tank, that failure mode disappears. Tankless units can still leak at connections or from a scaled heat exchanger, but the risk of a sudden tank rupture is gone. If your current tank is already leaking, see our guide to hot water tank leaking causes and fixes.
Disadvantages of Tankless Water Heaters
Higher Upfront Cost
A tankless water heater costs more to buy and more to install than a like-for-like tank. ProStar’s installation page puts a typical installed cost at $3,500 to $6,500, depending on unit capacity, brand, and any gas, venting, or electrical work. Lower energy bills and a longer lifespan can narrow the gap over time, but they rarely erase it in the first few years.
Installation Requirements
This is where most surprises happen. A tankless unit needs more of everything at once:
- Gas capacity. A tankless unit burns a lot of gas in a short burst. If your gas line or meter capacity is too small, it may need upgrading. Learn about gas line concerns on our gas line detection and repair page.
- Venting. Tankless units need properly sized, approved vent materials and a clear route to the outside.
- A condensate drain. High-efficiency condensing models produce acidic condensate that needs a proper drain.
- Power. Most gas models still need an electrical outlet for controls and the fan, so a power outage can mean no hot water. Electric models need far more electrical capacity, sometimes a service upgrade.
Gas fitting and venting are licensed work that needs a permit, so this is not a DIY job.
A Flow-Rate Limit
“Endless” has an asterisk. Every unit has a maximum flow rate. Run two showers, a dishwasher, and a washing machine together and an undersized unit will give you lukewarm water. The fix is correct sizing, or in some homes a second unit.
A Wait for Hot Water and Temperature Swings
Water still has to travel from the unit to your tap, so the wait depends on pipe distance. Some units also deliver a brief cold burst or temperature swing when you use hot water in short bursts. Recirculation options can help, but they add cost.
Hard Water and Scale
Calgary’s water comes from the Bow and Elbow rivers, and the City of Calgary describes it as hard, with hardness varying by season and location. Heating hard water leaves mineral scale inside a heat exchanger, which cuts efficiency and shortens life if it is ignored. Plan on yearly flushing. Our tankless water heater maintenance guide walks through descaling, and a water softener or filtration system can reduce the problem at its source.
Pros and Cons of Tankless Water Heaters at a Glance
| Pros | Cons |
| Hot water as long as you stay within the flow rate | Higher purchase and installation cost |
| About 30% less energy on average (ENERGY STAR certified, per NRCan) | May need a larger gas line, new venting, a condensate drain |
| 15 to 20+ year life with maintenance | Flow-rate limit with several fixtures running |
| Compact, wall-mounted | Brief delays and temperature swings |
| No large tank to rupture | Yearly descaling in hard water; no hot water in an outage for most models |
Are Tankless Water Heaters Worth It in Calgary?
Is a tankless water heater better than a tank? It depends on your house and how you use hot water. Tankless tends to be a good fit if:
- You have natural gas and a reasonably accessible venting route.
- Your household uses a lot of hot water, or you keep running out with a tank.
- Space is tight, or you are renovating the mechanical room anyway.
- You plan to stay in the home long enough to benefit from the longer lifespan.
It may not be worth it if:
- Your gas line, venting, or electrical service would need major upgrades.
- Your hot water use is very low, so there is little standby loss to eliminate.
- You are moving soon and will not see the payback.
- You are not willing to commit to yearly maintenance.
If you are weighing both types head to head, our tank vs. tankless water heater comparison covers the side-by-side details, and our guide to energy-efficient hot water heater replacements explains how efficiency ratings work.
Which Fuel? Natural Gas, Electric or Propane
Natural gas is the usual choice in Calgary and delivers higher flow rates than electric. Electric tankless units are simpler to vent but draw heavy electrical loads, which can be a major hurdle in older homes. Propane suits some acreage properties without natural gas, but Natural Resources Canada notes propane is a more expensive fuel and needs a storage tank and scheduled deliveries. If you live in Bearspaw, Springbank, Balzac, or a similar area, check which fuel your property has before choosing a model.
Calgary Considerations Before You Switch
- Cold incoming water. In winter, incoming water is colder, so the unit has to raise the temperature further. That reduces the flow a given unit can deliver, which is why sizing for winter conditions matters.
- Hard water. Plan for yearly descaling, and consider treatment.
- Older gas lines. Many tankless installs need a gas capacity check first.
- Permits and licensing. Gas work requires a licensed gas fitter and a permit.
What to Check Before You Buy
- Count your peak hot water use. How many fixtures run at once?
- Confirm your fuel and line size. Natural gas, electric, or propane, and the capacity of the line.
- Check the venting route and a condensate drain.
- Test your water hardness.
- Compare total installed cost, not just the unit.
- Get a licensed professional to size it for winter.
A free in-home assessment covers all six. See our tankless water heater installation service for what it includes, and ask about financing if the upfront cost is the sticking point.
Frequently Asked Questions
Are tankless water heaters worth it?
They can be, especially for households that use a lot of hot water, have natural gas, and plan to stay for years. Savings and payback depend on your usage, your install costs, and maintenance. A home needing major gas or venting upgrades may see a longer payback.
What is the downside of a tankless water heater?
The main downsides are higher upfront cost, installation requirements such as gas line, venting and drain changes, a flow-rate limit when several fixtures run together, and yearly descaling in hard water like Calgary’s.
Do tankless water heaters save money?
Usually, on energy. Natural Resources Canada says ENERGY STAR certified models use about 30% less energy on average than storage tanks. Whether that offsets the higher purchase price depends on how much hot water you use and what installation costs.
How long do tankless water heaters last?
Commonly 15 to 20 years or more with regular maintenance, versus roughly 10 to 15 for a tank. Scale from hard water is the biggest threat to lifespan, so yearly flushing matters.
Do tankless water heaters work in Calgary’s winters?
Yes, when sized for winter conditions. Incoming water is colder, so an undersized unit may struggle to deliver enough hot water at the temperature you want. Proper sizing is the key.
Do tankless water heaters need maintenance?
Yes. Yearly flushing and descaling is the standard recommendation, especially in hard water. If your unit is struggling, see our tankless water heater repair service.
Can a tankless water heater run out of hot water?
It will not run out the way a tank does, but it can fall short if demand exceeds its flow rate. Running several showers and appliances at once on an undersized unit gives lukewarm water.
Thinking About Switching to Tankless?
ProStar Plumbing & Heating has served Calgary homeowners since 1996. If a tank is failing and you are choosing between a new tank and tankless, we will give you an honest recommendation for your home. Check out our signs you need water heater service guide if you are unsure whether to repair or replace.
We install and service water heaters across Calgary, Airdrie, Chestermere, Cochrane, Okotoks, Springbank, Bearspaw, Crowfoot, Balzac, De Winton, Conrich, Delacour, and West Hills.
For a free assessment, contact us or call (403) 250-7232.