Can You Put a Timer on a Tankless Water Heater? The Surprising Answer

You invested in a tankless water heater for its promise of endless hot water and energy savings. Yet, you find yourself staring at the faucet, waiting. And waiting. That delay for hot water to arrive feels like wasted water and time, chipping away at the efficiency you were promised.

This common frustration leads many to ask: can you put a timer on a tankless water heater to fix this? The answer is more complex than a simple yes or no, but the solution could revolutionize your home’s hot water experience.

While putting a timer directly on the tankless unit itself is generally not recommended and often unnecessary, combining a timer with a specific piece of equipment is the key. This article will demystify the process, exploring why a direct timer is a bad idea and how the right system can deliver instant hot water, maximize your savings, and end the waiting game for good.

The Core Problem: Why You’re Waiting for Hot Water

Tankless water heaters are marvels of on-demand technology. Unlike traditional tank heaters that constantly store and heat a large volume of water, tankless units heat water instantaneously as it flows through the device. This is the source of their high energy efficiency; they only use significant power when you turn on a hot water tap. However, this is also the root of the “time-to-faucet” problem.

The delay you experience isn’t the heater failing to work. It’s the time it takes for the newly heated water to travel from the heater, through your home’s plumbing, to the specific faucet or showerhead you’ve turned on.

The cold water sitting in the pipes has to be pushed out first. This can be especially noticeable in larger homes where the distance between the heater and the point of use is substantial.

Why a Standard Timer Isn’t the Solution

A common misconception is that you can wire a standard electrical timer to a tankless water heater, much like you would with a conventional tank model, to schedule its operation. However, this approach is fundamentally flawed for on-demand systems.

Tankless heaters are designed to be “always on” in a standby state, ready to heat water the moment you need it. Cutting power to the unit completely with a timer would mean you’d have no hot water at all during the “off” periods, defeating the purpose of an on-demand system.

Furthermore, frequently cutting and restoring power can put undue stress on the sophisticated electronic components within modern tankless heaters.

This could potentially shorten the unit’s lifespan and void the manufacturer’s warranty. The real issue isn’t about scheduling when the heater *can* work, but about eliminating the wait for the water it produces.

The Real Solution: Timers and Recirculation Pumps

The most effective way to get instant hot water from a tankless system and incorporate a timer for efficiency is by installing a hot water recirculation pump. This system creates a dedicated loop that circulates hot water through your pipes, keeping it readily available at the fixtures. This means the moment you turn on the tap, warm water is already there.

Here’s where the timer comes in. A recirculation pump doesn’t need to run 24/7. That would be inefficient and could negate the energy savings of having a tankless heater in the first place. By connecting the recirculation pump to a timer, you gain precise control over when the system operates.

How a Timer-Controlled Recirculation System Works

The setup is elegantly simple. The recirculation pump is installed on your hot water line. The timer, which can be a simple mechanical one or a more advanced smart, programmable model, controls the power to the pump. You can program the timer to run the pump only during periods of high hot water demand.

For example, you can set the timer to activate the pump for an hour in the morning as your family gets ready for work and school, and then again in the evening during dinner and bedtime routines.

During the middle of the day or overnight when no one is using hot water, the pump remains off, saving electricity and preventing unnecessary cycling of your tankless heater.

This combination provides the best of both worlds: the instant gratification of hot water at the tap and the intelligent energy savings of a scheduled system.

Many modern tankless water heaters even come with built-in recirculation pumps or are designed to easily integrate with an external one. Some high-end models feature “smart” recirculation that learns your household’s usage patterns and automatically adjusts the schedule.

Types of Recirculation Systems

When considering this solution, it’s important to know there are a couple of primary types of recirculation systems:

• Dedicated Return Line Systems: This is the most efficient setup. It uses a separate, dedicated pipe to return the cooled-off water from the furthest fixture back to the water heater. This creates a true loop and is ideal for new construction or major remodels.
• Crossover or Under-Sink Systems: For existing homes where adding a new return line is impractical, these systems use the existing cold water line as the return path. A special valve is installed under the sink furthest from the heater, which allows the cooled hot water to be pushed into the cold water line and sent back to be reheated. While slightly less efficient, it’s a very effective retrofitting solution.

Benefits of a Timed Recirculation System

Pairing a timer with a recirculation pump for your tankless water heater offers a cascade of advantages that go beyond just convenience.

1. Instant Hot Water & Ultimate Convenience

This is the most immediate and noticeable benefit. No more waiting. No more turning on the shower and letting it run for minutes before stepping in. Hot water is available the moment you need it, provided the pump is scheduled to run.

2. Significant Water Conservation

The U.S. Department of Energy estimates that the average household can waste thousands of gallons of water per year just waiting for it to heat up. A recirculation system virtually eliminates this waste, which is not only good for the environment but also for your water bill.

3. Enhanced Energy Efficiency

While the pump itself uses some electricity, a timer ensures it only runs when necessary. This targeted operation prevents the energy waste of a continuously running pump and avoids the frequent, short cycling of the tankless heater that can occur with poorly managed recirculation. You maintain the core energy-saving benefits of your on-demand system.

4. Reduced Wear and Tear

By scheduling the recirculation, you reduce the overall runtime of both the pump and the water heater. This can lead to a longer lifespan for both components compared to a system that runs continuously.

Choosing the Right Equipment

When implementing this solution, selecting the right components is crucial for optimal performance and safety. Your choice of pump and timer should be guided by your specific needs and plumbing setup.

Selecting a Recirculation Pump

Look for a pump specifically designed for use with tankless water heaters. These pumps are built to handle the unique flow and temperature characteristics of on-demand systems. Brands like Grundfos, Taco, and Rheem offer popular and reliable models. Some kits even come bundled with a timer and the necessary valves for an under-sink installation.

Choosing a Timer

Your options for timers range from basic to high-tech:

• Mechanical Timers: Simple, affordable, and reliable. These use pins on a dial to set the on/off schedule.
• Digital Timers: Offer more precise programming, with options for different schedules on different days of the week.
• Smart Timers/Plugs: These Wi-Fi-enabled devices allow you to control the pump from your smartphone. You can adjust schedules on the fly, and many integrate with smart home systems like Alexa or Google Assistant for voice control.

For electrical connections, it’s important to understand the requirements. For instance, knowing if your setup does a tankless water heater need a GFCI breaker is a key safety consideration that a professional can help clarify.

Installation Considerations

While a seasoned DIYer might tackle this project, installing a recirculation pump involves both plumbing and electrical work. For safety and to ensure the system works correctly, hiring a licensed plumber or electrician is highly recommended.

A professional will ensure that the pump is installed correctly, that check valves are in place to prevent backflow, and that the electrical connections are secure and up to code. They can also advise on the proper wiring, such as the correct gauge of 8/2 or 8/3 wire for a tankless water heater connection, and ensure everything is properly housed within the appropriate water heater conduit wiring.

A Comparative Look: Timed Recirculation vs. Other Options

To put it all in perspective, here’s how a timed recirculation system stacks up against other scenarios.

Feature	No Recirculation	Continuous Recirculation (No Timer)	Timed Recirculation
Hot Water Wait Time	Long (depends on distance)	Instant	Instant (during scheduled times)
Water Waste	High	Low	Low
Energy Consumption	Low (heater only)	High (heater + constant pump use)	Optimized (heater + scheduled pump use)
System Wear & Tear	Standard	High	Low to Moderate
Upfront Cost	None	Moderate (pump cost)	Moderate (pump + timer cost)

The Final Verdict: A Smart Upgrade for Your Tankless System

So, can you put a timer on a tankless water heater? While you shouldn’t put a timer directly on the heater itself, you absolutely should use a timer to control a hot water recirculation pump. This combination is the definitive solution to the most common complaint about tankless systems—the wait for hot water.

By implementing a timed recirculation system, you transform your efficient, on-demand water heater into a high-performance machine that also delivers instant convenience.

You’ll save water, optimize your energy use, and finally enjoy the full spectrum of benefits that your tankless water heater was designed to provide. It’s a relatively small investment that pays huge dividends in comfort, conservation, and satisfaction every single day.