For short trips, you do not need to do anything with a tankless water heater because they only heat water on demand. For extended vacations, turn off the power, shut off the gas, and consider activating the unit’s built-in Vacation or Eco-mode to protect it against freezing temperatures.
Shut Off The Water Heater
If you have a gas water heater, you can turn the heater off at the source and shut off the gas valve. If you have an electric heater, it can be turned off at the breaker. Once off, you can open the valve or spigot on the water heater to drain the water into a pail or bucket.
No. Unlike traditional tank heaters, tankless water heaters heat water on demand. Because they do not store water, they technically never run out of hot water.
Whether you should use an indoor or outdoor tankless will also depend on the the home itself. Existing houses may benefit from an outdoor model, as there are not as many adjustments needed for the plumbing, and you likely will not need to make changes to your house for venting.
Will It Work Without Electricity? Electrical power is the only power that a gas tankless water heater cannot run without to provide hot water in your home. Even though the heating source needs gas, it requires electricity to power up all electrical parts to allow ignition, monitoring, and exhaust.
To keep your house warm without electricity, focus on shrinking the heated space by camping in one room, sealing drafts with rolled towels or blankets, and using safe indoor heating alternatives like portable propane heaters or hot water bottles.
A typical tankless water heater's lifespan often ranges from 15 to 20 years or more with proper care. In many cases, well-maintained systems can reach 25 to 30 years of service. That extended lifespan is one of the strongest considerations for homeowners researching how to choose a tankless water heater.
The primary drawbacks of tankless water heaters are their significantly higher upfront purchase and installation costs, restricted flow rates that can struggle to supply multiple high-demand fixtures simultaneously, and mandatory annual maintenance to prevent scaling.
In freezing temperatures, condensate produced by a condensing tankless hot water heater can freeze inside the drain line, which can cause leakage, operation issues or shutoff. To help keep your indoor tankless water heater from freezing, use a direct vent exhaust & intake system.
For larger households, multiple showers, laundry, and dishwashing may run at the same time. Hot water demand could reach 10–12+ GPM. A high-capacity tankless water heater—or even two units installed in parallel—may be the best solution.
If a standard showerhead is fitted, it will use around an extra half a gallon each minute, accounting for a 25-gallon emittance every 10 minutes, or 50 gallons throughout a 20-minute shower. *1 gallon = 4.54 litres.
For a 3-bathroom home, you generally need a tankless water heater with a flow rate of 7 to 9 GPM (Gallons Per Minute). This size can effectively run 2 to 3 major hot water fixtures (such as a shower and a washing machine) simultaneously.
Simply turn off the water supply to your home. It is easy to do and only takes a few minutes. Just locate the main shutoff in your home. If you are having trouble finding it, you can ask a professional plumber to help you locate it.
To compensate for heat loss, you may need to slightly increase the water heater's thermostat setting during winter. The recommended temperature is between 120–140°F for most households.
To put your water heater in vacation mode, simply locate the thermostat dial on the unit and turn it to the "Vacation" (or "VAC") setting. This lowers the temperature to around 50°F (10°C), saving energy while preventing the tank from freezing or growing harmful bacteria while you are away.
Tankless Water Heaters
When a cold snap hovers around or below 32 degrees Fahrenheit for a couple days in a row it's time to let at least one faucet drip. Pay close attention to water pipes that are in attics, garages, basements or crawl spaces because temperatures in these unheated interior spaces usually mimic outdoor temperatures.
Winterizing a tankless water heater (whether in an RV or a home) prevents trapped water from freezing and cracking the heat exchanger. The process requires isolating the unit, completely draining all internal water, and flushing the lines with non-toxic, food-grade RV antifreeze.
Plumbers often hesitate to recommend tankless water heaters because they act like high-performance sports cars. Unlike traditional tank models that are "workhorses" and can function while mostly ignored, tankless units require precise installation, regular maintenance, and are highly sensitive to mineral buildup.
Here are some common reasons why your tankless water heater might not be working and how you can troubleshoot these problems.
Yes, tankless water heaters are generally considered safer than traditional tank-style water heaters. Their design eliminates the risk of massive, catastrophic tank ruptures and lowers the risk of bacterial growth. Because they heat water on demand rather than storing it, they also reduce risks associated with overheating or pressure buildup.
Tankless water heaters actually use less electricity overall than traditional storage tanks. The U.S. Department of Energy (DOE) estimates they are 24% to 34% more energy efficient for typical households, because they only heat water on-demand and eliminate standby heat loss.
No, tankless water heaters do not use more gas overall. While they use intense bursts of energy to rapidly heat water on demand (often burning up to 200,000 BTU/hour), they are generally 22% to 34% more energy-efficient than traditional storage tanks.
A whole-home tankless water heater costs an average of $2,400, but costs can range anywhere from $1,600 to $3,800.