How To Plumb In A Water Heater With Return

Have you ever stood in the shower, shivering while waiting for the water to turn hot? It’s a frustrating daily ritual for millions of American homeowners. Installing a recirculating pump system is the ultimate solution, but many DIYers hesitate because they don’t know how to plumb in a water heater with return. This guide will walk you through the process safely and efficiently, turning your cold wait into instant comfort.

Why Install a Hot Water Recirculation System?

Before we dive into the wrenches and pipes, let’s understand why this upgrade is worth your time. A standard plumbing setup sends hot water from the heater to your fixtures. When you turn off the tap, that hot water sits in the pipes and eventually cools down. The next time you need hot water, you must push all that cooled water out before fresh hot water arrives.

A recirculation system solves this by creating a loop. It continuously or intermittently circulates hot water back to the heater, keeping the pipes warm. According to the U.S. Department of Energy, water heating accounts for about 18% of home energy use. While a pump uses electricity, it significantly reduces water waste. The average family wastes over 12,000 gallons of water annually just waiting for it to heat up. By learning how to plumb in a water heater with return, you are investing in both convenience and conservation.

Understanding the Two Main Types of Return Systems

Not all recirculation systems are created equal. Choosing the right one depends on your home’s existing infrastructure.

1. Dedicated Return Line System

This is the “gold standard” for new construction or major renovations. It involves installing a separate pipe that runs from the furthest fixture back to the water heater.

• Pros: Most efficient, balanced pressure, no cross-contamination between hot and cold lines.
• Cons: Requires running new piping through walls, which can be invasive and expensive in existing homes.

2. Comfort System (Under-Sink Crossover Valve)

This method is ideal for retrofits. It uses your existing cold water line as the return path. A special valve is installed under the sink furthest from the heater.

• Pros: Easy installation, no new pipes needed, cost-effective.
• Cons: Cold water lines may feel lukewarm initially; slightly less efficient than a dedicated line.

For this guide, we will focus on the Dedicated Return Line method, as it represents the true definition of plumbing a “return.” However, the principles apply broadly to understanding flow dynamics.

Tools and Materials You Will Need

Preparation is key to a successful plumbing project. Gather these items before shutting off your water supply:

• Pipe Cutter or Hacksaw: For clean cuts on copper or PEX.
• Propane Torch and Solder: If working with copper pipes.
• PEX Crimping Tool: If using PEX tubing (recommended for DIYers).
• Adjustable Wrenches (2): For tightening fittings.
• Teflon Tape and Pipe Dope: For sealing threaded connections.
• Recirculation Pump Kit: Ensure it includes check valves and union connections.
• Safety Gear: Gloves and safety glasses.

Pro Tip: Always check local building codes. Some jurisdictions require a licensed plumber for water heater modifications. For more information on residential plumbing standards, you can refer to general guidelines on Wikipedia’s Plumbing page.

Step-by-Step: How To Plumb In A Water Heater With Return

Follow these steps carefully. If you are unsure at any point, consult a professional.

Step 1: Shut Off Power and Water

Safety first. Turn off the electricity to your electric water heater at the breaker box, or set the gas valve to “Pilot” for gas units. Close the cold water inlet valve on top of the water heater. Open a hot water faucet elsewhere in the house to relieve pressure and drain residual water.

Step 2: Identify the Return Connection Point

Locate the cold water inlet on your water heater. Most modern recirculation pumps are designed to connect here. You will need to create a “T” connection.

• Cut the cold water inlet pipe about 6–8 inches above the heater.
• Install a tee fitting. One end goes to the heater, one to the main cold supply, and the third will connect to your return line.

Step 3: Install the Check Valve

This is a critical component. A check valve ensures water only flows in one direction—into the heater, not back into the main supply.

• Install the check valve on the cold water inlet side, ensuring the arrow points toward the water heater.
• Use Teflon tape on threaded connections to prevent leaks.

Step 4: Connect the Recirculation Pump

Mount the pump according to the manufacturer’s instructions. Most pumps come with union connections, making them easy to install and remove for maintenance.

• Connect the pump’s outlet to the tee fitting on the cold water inlet.
• Ensure the pump is oriented correctly (usually marked with an arrow for flow direction).

Step 5: Run the Return Line

If you have a dedicated return line:

• Connect the return pipe from your furthest fixture back to the suction side of the pump.
• If you are retrofitting without a dedicated line, install the crossover valve under the furthest sink. Connect the hot and cold lines at that sink using the provided kit. The “return” path is now the cold water pipe.

Step 6: Prime and Test

Open the cold water inlet valve slowly. Allow the tank to fill completely. Open hot water faucets throughout the house to bleed out air bubbles. Once water flows steadily, close the faucets.

• Turn the power back on to the water heater.
• Plug in the recirculation pump.
• Set the timer or thermostat on the pump. For energy efficiency, set it to run only during peak usage times (e.g., 6 AM–9 AM and 5 PM–9 PM).

Common Mistakes to Avoid

Even experienced DIYers can stumble. Here are pitfalls to watch out for:

Frequently Asked Questions (FAQ)

1. Does a recirculation pump increase my electric bill?

Yes, but marginally. A typical pump uses between 50–100 watts. However, you save money on water bills and reduce the workload on your water heater by maintaining temperature. Using a timer or smart control minimizes energy usage.

2. Can I install a return system on a tankless water heater?

Absolutely. In fact, tankless heaters benefit greatly from recirculation because they can suffer from “cold water sandwiches” (a burst of cold water between hot bursts). Ensure your tankless model is compatible with external pumps.

3. How long does it take to install a recirculation system?

For a professional, it takes 2–4 hours. For a DIYer with moderate skills, expect to spend a full day, especially if running new PEX lines through walls. Using an under-sink crossover kit can reduce this to 1–2 hours.

4. Is a dedicated return line better than a crossover valve?

Yes, a dedicated return line is superior for performance and longevity. It prevents lukewarm water in your cold taps and reduces wear on the pump. However, crossover valves are a practical compromise for existing homes where running new pipes is impossible.

5. What size pump do I need?

Most residential homes require a pump with a flow rate of 10–15 gallons per minute (GPM) and a head pressure of 10–15 feet. Check your home’s square footage and pipe diameter. When in doubt, consult the pump manufacturer’s sizing chart.

Conclusion

Learning how to plumb in a water heater with return is a transformative home improvement project. It eliminates the daily frustration of waiting for hot water and contributes to a more sustainable household by reducing water waste. Whether you choose a dedicated return line for maximum efficiency or a crossover valve for ease of installation, the result is immediate comfort.

Remember, proper planning and adherence to safety protocols are crucial. Take your time, double-check your connections, and enjoy the luxury of instant hot water. If you found this guide helpful, please share it with friends or family who are tired of cold showers!