How to Plumb a Hot Water Recirculation Loop

Plumbing a hot water recirculation loop is relatively easy. However, plumbing the system in a way that saves you energy is the trickier part. A hot water recirculation system is a plumbing system that allows water to move to fixtures faster without waiting for water to get hot. Instead of relying on low water pressure, which is common in water lines, a hot water recirculation loop quickly moves water from your heater to the fixture.

Depending on how big your home is and the length of your plumbing pipes, you may wait for hot water to reach some fixtures for longer from the water heater which is located some distance away. Besides, you may end up wasting hundreds of gallons of water in the process of waiting for your hot water to be delivered which is unacceptable; especially if you are environmentally conscious.

So, if you want to get instant hot water without the need for wasting water, consider plumbing a hot water recirculation loop, or have one installed by a professional plumber. In fact, the principle of a hot water recirculation system is fairly simple.

You only need to install a recirculating pump in your plumbing lines to create a loop that constantly circulates water in hot water lines and the heater for reheating. As such, whenever you open your bathroom hot water faucet or sink faucet, warm water flows out immediately because it is already present in those lines.

Learning how to plumb a hot water recirculating loop will efficiently help you reduce your wait time for hot water as well as the money you could otherwise use in hiring a professional plumber.

Different Types of Hot Water Recirculation Loop

When it comes to the hot water recirculation loop, there are many options to consider. Here are some types you should consider installing.

Traditional Hot Water Recirculating Loop

The traditional hot water recirculating loop is a system where a dedicated return line for the hot water lines exists and they run from the bathroom or fixtures back to the water heater. The traditional hot water recirculating loop is installed near the water heater.

That way, the recirculating pull draws the water for the furthest fixture and delivers it into the water heater, thus creating a loop. The created loop ensures hot water goes throughout the house, therefore, whenever the fixture is used, hot water immediately flows out.

If your plumbing system has a dedicated return pipe, the traditional hot water recirculating system offers the best option. Besides, it allows the installation of pumps with inbuilt timers to enable the circulation pump to run only when hot water is needed, hence saving you energy bills.

On-Demand Hot Water Recirculating Loop


The on-demand hot water recirculating loop is a system that requires the user to activate the pump whenever hot water is needed. The system can be in a traditional style with the pump at the water heater with a dedicated return line. It can also be an under-the-sink pump that is plumbed in the farthest sink to deliver hot water all over the house.

Once you activate the pump, cooling water is pumped into the hot water pipes back into the cold water line for delivery into the electric water heater, thus creating a temporary loop as the water gets heated. So, instead of the cooled water being wasted by letting it flow down the drain as you wait for the heated water, it is sent back to the water heater for reheating.

As the water is delivered through the hot water pipe to attain the desired temperature, the pump will shut off and hot water will be running out of the faucet instead of looping back through the cold water lines.

The on-demand hot water recirculation loop allows you to have control over your hot water in a very convenient way. Although pushing the button to the pump gives you the impression that you will have to wait for the water to get hot, the system allows activation via wireless remote or by installing multiple buttons wherever it is convenient in the house.

Besides, some advanced systems come with motion sensors that will sense the flow of water automatically, turning on and shutting off automatically. Whichever way, installing hot water on-demand is a great option for conserving energy as well as water.

Instant Hot Water Recirculating Systems

The instant hot water recirculating loop is similar to the on-demand-hot water recirculating system and does not need a dedicated hot water return loop. For this case, it can be installed and used in aby house. More importantly, it can be installed in any house and comes with different types to choose from.


In the over-the-water-heater instant hot water recirculating system, the pump is installed above the water heater while the check valve is located under the sink furthest from the hot water heater. At this location, the pump will pressurize the hot side of the system and through the bypass valve under the sink to push the hot water into the cold system thus creating a hot loop.

The loop is able to run constantly or can be paired with a timer that can be built inside the unit. The timer will allow you to run the pump conveniently whenever you want hot water. Connecting the recirculation loop check valve to the system under the sink furthest from the water heater will allow the system to quickly deliver hot water to all faucets along the pipe since the hot water is flowing throughout the house.

You need to have a power plug near the water heater for convenient plugging of the pump. This system is advantageous as it allows installation with all types of pipes and it is generally maintenance-free. However, the system’s main drawback is that the loop pushes water into the cold pipes.


The under-the-sink style instant hot water circulation loop is installed under the sink that is furthest from the water heater. When this system is located at this position, it conveniently pushes warm water into the cold lines so that you get instant access to hot water in all fixtures.

Under-the-sink systems can be paired with a time and often come with built-in sensors that will conveniently turn on whenever the water temperature drops below the desired set temperature. Besides, with the timer function, you can set the time you need hot water and the system will deliver once you open the faucet.

How to Plumb a Hot Water Recirculation Loop

A hot water recirculation loop comes with plenty of disadvantages over other water systems. For instance, it delivers instant hot water at your convenience. Because of this, most people opt to switch to these systems.

However, proper installation of these systems is key. For this reason, we have prepared a step-by-step on how to plumb a hot water recirculation loop to enable you to install your recirculation hot water loop safely and without hassle.

Steps to Follow

Set Up the Loop

Since hot water rises and the cold water sinks, you will need to set up a loop to ensure your hot water is delivered via a recirculating loop. So, to create this, it is important to install copper pipes to let the water circulate through the system.

Start setting up the loop at the water heater and let it run all through the sources of hot water in your house. Since a return loop is required in this system, piping must be done running in the opposite direction. If you don’t set plumb up a loop, the hot water cannot circulate throughout the system.

Plumb a Special Water Pump

The second step is to install a special water pump to aid in water recirculation. To do this, you need to examine the location where your hot water heater is located. Should the pipes need dipping below the water heater, then it is best to plumb a recirculating water pump to resist gravity.

These special pumps don’t come with much pressure and they aren’t as fast as conventional ones. Regardless, their job is quite easy, to push water through the loop system at a steady rate. Most importantly, installing the special pump will prevent the system from experiencing low water pressure at the faucet due to the recirculating hot water loop.

Insulate the Loop

Loops meant to recirculate hot water for homes are created from copper pipes and are thus not as energy efficient. This is because these pipes usually lose heat to the surrounding environment thus you may end up reheating water to the desired temperature level often. This can significantly impact your electricity bills. However, the situation can be remedied with a little insulation of these pipes. Fitting insulation materials over these pipes will enable you to lower your water-heating bill.

Check for Air Locks

You need to carefully examine your hot water recirculating system at this point. Make sure you have not left a trap for air to accumulate. Having air in your plumbing system will disable your recirculating loop.

Install Check Valve

Install a check valve near the end of the loop where the pipe starts to meet the lower end of the water heater. The check valve will only let hot water into your loop system. That way, you won’t be surprised by sudden flashes of freezing water when you turn on your shower faucet.

Final Connection

At the bottom of your water heater, there is a drain valve. Remover this drain valve and in its place put an insulated nipple. That way, you will reduce the corrosion effect on the system. Install a tee fitting with female threads on the tee to enable you to screw back the drain valve. The other end of the fitting will enable you to connect the loop to the water heater.

Consider installing a ball valve on the loop side of the tee. That way, if you want to drain the water heater, you can do so by shutting off the ball valve thus preventing all the water in the loop from coming out of the boiler drain.

Shut Offs

Make sure that you have the shut-off valve plumbed on the cold water supply line of the system only. If the shut-off valve is installed anywhere else on the loop system, it might pose a safety risk, especially if the pressure in your water heater builds up and is not let out in a proper way through the release valve. So, be sure to check your system carefully and ensure nothing is out of place, particularly the shut-off valves.


The hot water redistributing loop system is an innovative plumbing system that can help you have convenient access to hot water while saving on water and energy in your home. To this point, we believe you have grasped how to plumb a hot water recirculation loop in your home.

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