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Quick Answer
Yes, you can use a circulating pump with a tankless water heater. The circulating pump helps recirculate hot water through the pipes back to the water heater so that hot water is readily available whenever you turn on a faucet. This reduces the time waiting for hot water to reach the faucet.
How Do Tankless Water Heaters Work?
Tankless water heaters, also known as on-demand or instantaneous water heaters, do not store heated water like conventional tank-style heaters. Instead, they use high-powered heating elements that quickly heat water as it flows through the unit. When you turn on a hot water tap, cold water enters the tankless unit where it is rapidly heated before being dispensed via the hot water plumbing lines.
The major advantage of tankless water heaters is that they provide a continuous, unlimited supply of hot water on demand. You never run out of hot water with a tankless heater. They also tend to be more energy efficient than tank heaters because they only heat water when needed rather than maintaining a tank full of hot water ready to go.
However, one downside of tankless heaters is that there can be a slight delay before hot water reaches taps that are far from the heater. This is because the cold water in the pipes first needs to make its way to the heater to be warmed up.
Benefits of Adding a Recirculation Pump
Installing a recirculation pump along with a tankless water heater can help overcome the issue of delayed hot water delivery. A recirculation pump works by continuously circulating hot water from the heater through the hot water plumbing lines and back to the heater. This creates a loop that keeps hot water primed in the pipes.
When you turn on a hot water tap, hot water is then immediately available because it has been circulating through the pipes. There is no cool down period waiting for the cold water to reach the heater. This results in much faster hot water delivery, usually only a few seconds, like what you expect from a tank heater.
Other benefits of adding a recirculation pump include:
- More convenience by reducing wait times for hot water
- Less water wasted waiting for hot water
- May qualify for energy rebates in some areas
How to Add a Recirculation System
Here are the basic steps for adding a recirculation pump to a tankless water heater system:
- Install a small recirculation pump near the tankless unit.
- Run a dedicated return line from the end of the hot water plumbing system back to the heater.
- Connect the return line to the recirc pump inlet.
- Connect a line from the pump outlet to the heater’s cold water inlet.
- Install a thermal valve (aquastat) near the heater to prevent overheating.
- Install a check valve on the return line to prevent backflow.
- Set the pump timer to activate every 2-3 hours for 10-15 minutes.
This creates a complete loop system that circulates hot water throughout the house back to the heater. The pump timer allows the system to turn on periodically to keep hot water circulating.
Key Recirculation Pump System Components
| Component | Purpose |
|---|---|
| Recirculation pump | Pumps hot water through the recirculation lines. |
| Dedicated return line | Provides a loop for hot water to circulate back to the heater. |
| Aquastat | Prevents overheating by shutting off the pump if water gets too hot. |
| Check valve | Prevents backflow of water in the wrong direction. |
| Timer | Turns the pump on periodically to circulate the hot water. |
Considerations Before Installing a Recirculation System
There are a few factors to consider before deciding to install a recirculation pump system:
- Installation costs can range from $500-$2,000 depending on system complexity.
- Operation costs will be higher due to increased water and energy use.
- The pump uses some electricity, usually 35-100 watts.
- More strain is put on the water heater cycling hot water through it.
- Regular pump maintenance will be required.
For larger homes with long pipe runs, the benefits often outweigh the costs. But for smaller living spaces, the extra costs may not make sense.
Conclusion
Yes, it is possible to install a hot water recirculation pump along with a tankless water heater. This will provide instantaneous hot water delivery by keeping hot water circulating through the plumbing system. While it does have higher operating costs, the added convenience can make it worthwhile, especially in larger homes. Proper installation is key to ensure the system runs efficiently and reliably. Considering the pros and cons ahead of time will help determine if adding a recirculation pump is the right choice for your tankless water heater.