What is a tankless hot water heater?
A tankless hot water heater, also called an on-demand heater, does not store hot water. Instead, it heats water instantly as it flows through. When you turn on a hot water tap, cold water passes through a heat exchanger that is rapidly warmed by an electric element or a gas burner. The result: no waiting for a storage tank to refill, and effectively endless hot water.
Practically speaking, water heats in seconds. Depending on how far the heater is from the fixture, you will feel hot water flowing within 5 to 15 seconds. A traditional tank that has run out of hot water can take 30 minutes or more to recover. A tankless unit does not run out the same way.
The efficiency advantage is real. Because the unit only heats water as needed, you are not paying to keep 40 or 50 gallons of water hot all day. That is why tankless heaters often save money over time.
Electric versus gas
Both types heat on demand, just with different energy sources.
Electric tankless units. Use heating elements to warm water. Easier and cheaper to install. Compact, ideal for smaller homes or point-of-use installs. No venting required.
Gas tankless units. Use a gas burner. Higher upfront install cost. Require proper venting and gas lines. Typically deliver higher flow rates, which suits larger households.
The right choice depends on hot water demand and your existing setup. Both are effective, but they have different install requirements and operating costs.
Sizing a tankless unit
Tankless heaters are rated by flow rate (litres per minute, or LPM), not storage capacity. Some typical demands:
- A shower: 6 to 9 LPM
- A dishwasher: 4 to 6 LPM
- A washing machine: 6 to 8 LPM
If multiple fixtures run at once, you need a unit that handles the combined flow. As a starting point:
- Small home or condo: 5 to 7 LPM
- Average home, 2 to 3 occupants: 7 to 10 LPM
- Large home with high simultaneous usage: 10+ LPM
Proper sizing ensures you never run out, especially when groundwater is at its coldest in winter.
Installation considerations
Install depends on the model and your home's current setup:
- Electric models may need upgraded wiring or a new breaker
- Gas models require venting and sufficient gas flow
- Most are wall-mounted to save space
Our team handles the full process: consultation, sizing, and code-compliant install.
Is a tankless heater right for you?
A few practical questions to think through:
Are tankless heaters worth it? For many households, yes. Long-term energy savings, longer lifespans, and endless hot water make them a smart investment if you plan to stay in your home.
Is an electric tankless heater worth it? For smaller homes or point-of-use needs, yes. Energy-efficient and easier to install. May struggle with high simultaneous demand in larger households.
Do tankless heaters work in Ottawa winters? Yes, when properly sized and installed. Modern units are designed for cold Canadian groundwater. Gas models tend to perform better than electric in high-demand, cold-weather situations.
If space savings, efficiency, and modern convenience matter, switching from a traditional tank is a smart move. If you are still weighing the options, our team is happy to walk through the trade-offs for your specific household.
