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In the world of tankless water heaters, there is often confusion surrounding the term on demand. Although many of us first encountered this term as it pertained to streaming television, it has found a common (and often misleading) place as a tankless water heater feature.
The truth of the matter is "hot water on demand” implies that hot water is being delivered to the faucet instantly. This can seem accurate, but "instantly" technically means zero delay, which is not true. No water heater delivers hot water instantly.
Why does it take time to get hot water from a tankless water heater?
Although Navien tankless water heaters do provide an endless supply of hot water, the arrival of hot water is not instant.
This is because the average time it takes a Navien tankless water heater to heat water and send it on its way to the faucet is approximately 5-10 seconds.
Tank water heaters can be slightly faster because they have a preheated supply of hot water ready and waiting — although maintaining this supply is a constant waste of energy.
How does hot water on demand work?
The length of time it takes a tankless water heater to raise the water temperature and deliver it to the faucet at a heated level depends on two main factors.
- Temperature rise – This is the difference between inlet ground water temperature and the temperature setting the water heater is set at. In other words, if the water drawn into the house arrives at 40 degrees Fahrenheit compared to 50 degrees Fahrenheit, there will be a variance in the time it takes to heat it to the desired temperature.
- Length of piping - The distance between the on-demand water heater and the hot water fixture (such as a shower) affects the time it takes the hot water to travel from the water heater, through the pipes and reach the faucet.
How can you get faster hot water from an on-demand water heater?
Most Navien tankless water heater models can have an optional recirculation system installed which delivers hot water at a faster rate.
This recirculation system can be activated anywhere in the home by the Navien HotButton switch. True to its name, when hot water is needed, you merely press a button which activates a recirculation pump and gas-fired burner to heat water in supply lines. This gives you hot water when you need it. The Navien recirculation system is both cost effective and energy efficient.
A Navien tankless water heater with a recirculation system can also deliver faster hot water based on your lifestyle and daily/weekly routine. Your Navien tankless water heater can be scheduled to preheat the water in your supply lines through the control panel. The EZNav control panel has intuitive scheduling settings for Always On, Weekly and Intelligent Recirculation which learns the user's hot water usage pattern.
Do on-demand tankless water heaters require special pipes?
On-demand condensing tankless water heaters can use standard PVC (plastic) vent pipes because the exhaust gas is cooler. But on-demand non-condensing tankless water heaters have much hotter exhaust gas and typically require metal venting material.
Are there rebates for on-demand water heaters?
Depending on where you live, you may qualify for a rebate or tax credit for a new Energy Star certified on-demand tankless water heater. Learn more in our rebate center.