Are you tired of waiting for hot water to reach your faucets? A hot water recirculating pump might be the solution you’re looking for. This device can save time, water, and energy by making hot water readily available at your taps. We recommend professional installation for this project, but it’s helpful for homeowners to understand how these systems function.
In the video above, This Old House plumbing and heating expert Richard Trethewey explains how a recirculating pump works and its benefits. Below, we’ll recap these details and answer some common questions about hot water recirculating pumps.
How Hot Water Recirculating Systems Work
Hot water recirculating systems provide instant hot water at your faucets, eliminating the need to clear the pipes with cold water. This is particularly helpful in larger homes or buildings where the water heater is far from the point of use.
These pumps operate by continuously circulating hot water through your plumbing system. Here’s how:
- A separate water pipe, called a recirculation line, runs from the farthest plumbing fixture back to the water heater.
- A pump at the water heater moves hot water through this line.
- Any cold water in the recirculation line is returned to the heater for reheating.
- When you turn on a hot water tap, hot water is immediately available.
Pro Tip: Richard Trethewey, This Old House plumbing and heating expert, explains the problem recirculating pumps solve: “Think about the issue in most of these bigger houses, we’ve got a water heater somewhere in the basement in the garage, but it’s a long way from that water heater to the furthest plumbing fixture in the house. When you want hot water at that furthest point, you’ve got to empty all the cooler water that’s been sitting in that pipe before you can get any hot water. And all that cool water is literally going down the drain.”
Richard Trethewey warns that an improperly controlled recirculating system can waste energy. Smart controls are essential—options include timers that activate the pump only during peak usage times like mornings and evenings, occupancy sensors triggered by a bathroom door closing, and even self-learning units that monitor your hot water usage patterns and program themselves automatically.
In homes without a dedicated recirculation line, a retrofit-friendly option uses the existing cold water pipe as the return path. As demonstrated on a This Old House project, a small pump installed at the farthest fixture pushes standing cooled water from the hot water pipe across into the cold water line, which carries it back to the water heater. A sensor at the fixture detects when hot water has arrived and automatically shuts the pump off—so hot water never mixes into your cold supply. This approach means you get instant hot water without running a single new pipe.
Components of a Recirculating System
A typical hot water recirculating system consists of the following components.
- Aquastat: A temperature-sensing device that shuts off the pump when hot water returns to the heater
- Check valve: Ensures that water flows only in one direction, preventing backflow
- Recirculation line: The dedicated pipe that carries water back to the heater
- Recirculation pump: The heart of the system, responsible for moving water through the pipes
- Timer: Controls when the system operates, allowing you to turn it off when you’re asleep or away
Modern systems often combine multiple components into a single unit for easier installation and operation.
Pro Tip: Modern all-in-one units simplify installation significantly. As Richard Trethewey showed on This Old House, newer models combine a check valve, timer, and temperature sensor into a single plug-in unit. Some even have built-in intelligence that watches how much water you use and when you use it, programming itself automatically to match your household’s hot water habits—no manual timer setup required.
One key component worth understanding is the crossover valve, which connects between the hot and cold water supply lines at a distant fixture. As Richard Trethewey demonstrated on This Old House, the crossover valve contains a bimetallic element inside that opens and closes based on temperature. In normal mode, hot water flows up to the faucet. But when the water in the line has cooled, the valve opens and the recirculation pump pushes that standing water across into the cold water side—sending it back to the heater to be rewarmed instead of wasting it down the drain.
Benefits of Installing a Hot Water Recirculating Pump
Installing a hot water recirculating pump offers several advantages.
- Convenience: Provides hot water on demand throughout your home
- Energy savings: Properly controlled systems can be more energy-efficient than traditional setups
- Water conservation: Reduces water waste by eliminating the need to run taps while waiting for hot water
Although these systems can be expensive upfront, for some homeowners, the long-term benefits can justify the price.
Types of Recirculating Pump Systems
The recirculating pumps themselves can be included in several different systems that work for different home layouts and hot water needs.
Full Recirculation Systems
Full recirculation systems require a dedicated return line from the farthest fixture back to the water heater. While these systems are effective, they can be challenging to install in existing homes due to the need for additional plumbing. However, they eliminate cold water in the lines, providing the easiest, most efficient path for getting hot water from your fixtures.
Point-of-Use Pumps
Point-of-use pumps are installed at specific fixtures, as Trethewey shows with the system in the bathroom vanity. These are easier to retrofit in existing homes but may not be as efficient as full systems. They’re convenient for homeowners who want instant hot water at particular locations.
Retrofit Systems Using Existing Lines
Some systems can use existing cold water lines as the recirculation line, simplifying installation. These solutions often involve a pump at the water heater and a valve at the farthest fixture to move heated water as needed. This method reduces the need for extensive plumbing modifications, but cold water still recirculates back to the heater instead of being wasted down the drain.
Recirculating Pump Installation Considerations
Installing a hot water recirculating pump requires careful planning and execution. Here are some key factors to consider:
- Electrical requirements: Make sure the pump has the proper electrical connections available to function effectively.
- Local building codes: Always check and comply with local regulations to ensure a safe and legal installation.
- Plumbing layout: The complexity of your home’s plumbing will affect the installation’s difficulty.
- Pump location: These units are typically installed near the water heater for optimal performance.
Choosing the Right System for Your Home
Consider the above factors and your budget to help you determine the best recirculating pump for your home. We recommend consulting a professional to make an informed decision. A consultation can also address any concerns you may have about installation, maintenance, and potential energy savings.
Professional Installation vs. DIY
We recommend having a licensed plumber install a hot water recirculating pump for you. As Trethewey says, “A recirc[ulating] line improperly controlled could be one of the biggest energy wasters in the whole building.” Do-it-yourself (DIY) installers could end up accidentally wasting hot water and overworking the water heater. A professional also knows how to comply with local building codes.
Optimizing Recirculating Pump Performance
To get the most out of your recirculating pump, consider these tips:
- Adjust the aquastat to an appropriate temperature to balance comfort and energy efficiency.
- Insulate hot water pipes to minimize heat loss and maintain water temperature.
- Regularly maintain and clean the pump to ensure efficient operation and longevity.
- Use a timer to operate the pump only during peak usage times, reducing unnecessary energy consumption.
- If possible, invest in smart controls that will automatically optimize the pump for your household’s water usage patterns.
- Check the system regularly for wear, leaks, and proper function according to the manufacturer’s instructions for maintenance.
Environmental Impact of a Recirculating Pump
Installing a hot water recirculating pump benefits the environment by reducing water waste and optimizing your energy use. However, it’s crucial to use timers and aquastats effectively to ensure you’re saving rather than expending extra energy. Also, consider the energy source for your water heater. Homes using renewable energy sources will find even more environmental benefits.
Technological Advances in Recirculating Systems
Technological advancements have made recirculating pumps smarter and more efficient in recent years. Modern systems can learn your household’s hot water usage patterns and adjust operations accordingly. Some of these systems integrate with home automation platforms, allowing homeowners to control and monitor their recirculating pumps via smartphone apps.
Integration with home automation systems allows homeowners to set schedules, monitor energy consumption, and receive maintenance alerts. These features make it easier to manage the system efficiently and ensure continuous optimal performance.
Maintenance Tips to Extend a Recirculating Pump’s Lifespan
Proper maintenance extends your hot water recirculating pump’s lifespan and keeps it operating efficiently. Here are some maintenance tips to keep your system in top condition.
- Inspect the pump regularly for any visible signs of wear or damage.
- Clean the system to remove any sediment or build-up that may hinder performance.
- Test the check valve to make sure it’s functioning correctly and preventing backflow.
- Monitor the aquastat settings to maintain appropriate water temperature.
Common Questions About Hot Water Recirculating Pumps
Should a hot water recirculating pump run all the time?
No, a hot water recirculating pump should not run continuously. Using a timer or smart controls to operate the pump only during peak usage times can significantly reduce energy consumption while still providing the convenience of instant hot water when needed.
Does a hot water recirculating pump use a lot of electricity?
While a hot water recirculating pump does consume some electricity, modern efficient models used properly (with a timer, for example) can minimize energy consumption. The energy savings from reduced water heating needs can often offset the pump’s electricity usage.
How long should it take to get hot water with a recirculating pump?
With a properly functioning recirculating pump, you should have hot water almost instantly when you turn on the tap. The exact time may vary slightly depending on your home’s plumbing layout and the distance from the water heater, but it should be significantly faster than without a pump.
