Hot Water Recirculating Pumps-Design, Pros, Cons, Alternatives

Hot water recirculating pumps are installed in homes and business premises to prevent water wastage and also eliminate the time you have to wait to get hot water after turning on the hot water faucet.

Whenever you need to take a shower or wash your hands with hot water, hot water does not immediately flow out of the shower head or sink faucet. You have to wait for a few seconds or even more than a minute to have hot water flowing out.


Why is that though? There is a hot water line from the water heater to your shower. The last time the shower was used, the water in the line was hot, but as soon as the shower ended the hot water did not flow back to the heater.

Instead, the hot water remained in the pipe where it cooled off. When you turn on the hot water faucet in your shower, hot water from the water heater has to first push out the cold water in the line. The further the shower/sink is from the water heater the longer it will take to get hot water and the more cold water you will lose down the drain.

A hot water recirculating pump is a pump installed on your water heater to create a loop between the farthest fixture in your house and the water heater. The loop allows for continuous circulation of hot water in the house ensuring you get hot water immediately you need it.

Quick Guide

Let us start with a quick guide on the pros and cons of hot water recirculation systems:


  • Instant Hot Water: Recirculating pumps provide immediate hot water at the tap, eliminating the need to wait for the water to heat up, which can save time and reduce water wastage.
  • Water Conservation: By reducing the wait time for hot water, these pumps can significantly decrease water waste, conserving both water and energy.
  • Energy Efficiency: While they do consume energy to operate, recirculating pumps can be set on timers or demand-based sensors, ensuring they only run when needed, which can result in energy savings.
  • Convenience: They make it more convenient to access hot water quickly, particularly in larger homes with long plumbing runs.


  • Initial Cost: The cost of purchasing and installing a recirculating pump, along with any required additional plumbing, can be relatively high, which may deter some homeowners.
  • Operating Cost: While they can be energy-efficient when used with timers or sensors, recirculating pumps do consume electricity continuously if not properly controlled, potentially increasing energy bills.
  • Installation Complexity: Retrofitting a recirculating pump into an existing plumbing system can be complex and may require professional installation.
  • Maintenance: Over time, recirculating pumps may require maintenance, such as periodic cleaning or replacement of components, which adds to the overall cost of ownership.
  • Noise: Some recirculating pumps can generate noise, which can be a concern in quiet living spaces. However, newer models are designed to operate quietly.

How Does a Hot Water Recirculation System Work?

point of use, undersink hot water recirculation pump

The aim of installing a hot water recirculation system is to cut down on water wastage and also avoid having to wait for up to a minute to get hot water in a faucet/shower head. By the way, how much water is wasted by having to wait until all the cold and lukewarm water flows down the drain before taking a shower?

Most shower heads have a flow rate of 2.5 gallons of water per minute. If you have to wait for hot water to start flowing out for about 50 seconds, you will waste about 2 gallons of water down the drain. Multiply this by the number of fixtures in the house for a period of 30 days. That is a lot of water and time wasted.

To solve this problem, you can install a hot water recirculating system in your house. This system uses a pump to push back unused hot water to the water heater while making sure that you are able to get hot water instantly when you need it through recirculation.

For people living in California, this may not be a choice. Title 24 of the California Code of Regulations requires installation of hot water recirculation systems if the distance between the water heater and a faucet is or exceeds 50 feet.

There are 2 types of hot water recirculation systems. Let us look at how they work and differ from each other.

1. Full Recirculation Pump System

If you live in an old house (built before 1980) your house has a single pipe system. In that system, one pipe carries hot water from the water heater through all the fixtures in your house all the way to the farthest fixture.

Newer buildings have a dedicated return pipe which connects the furthest fixture back to the water heater. Take time to know which pipe system you have in your house.

If you have the old pipe system, this will be a little expensive for you. A plumber will need to install an additional hot water line from your farthest fixture and link it up with the water heater.

That will be your house’s dedicated hot water return pipe. Hot water in the supply pipe that has not be used will sent back to the water heater instead of cooling off in the pipes.

Hot Water Recirculation Pump Diagram

To illustrate how a hot water recirculation system works, let us look at the schematic below courtesy of

When the dedicated return pipe sends the water back to the heater, fresh hot water from the water heater will take its place. This will ensure that hot water is always circulating throughout your house and you don’t have to wait, or waste any down the drain.

When I mention this system to most people, their immediate concern is the overall costs of running and sustaining it. The truth of the matter however is that there will not be a considerable change in your energy bills if you get a professional to do the work for you.

Hot water recirculation pumps usually come with sensors. The sensors are able to detect the temperature of water in the supply pipes and will therefore only come on if the temperature falls below a certain level. The pump will therefore not be running throughout.

In addition to sensors, hot water recirculating pumps also come with mechanical or electronic timers, to help you regulate when you want the water to recirculate and when you need the pump to be idle.

For instance, you can turn off the pump at night and during the day when you are at work. Mechanical timers are easy to reset and repair than electric ones.

You can also go a step further and install a smart hot water recirculating pump system. These system studies your household’s hot water usage habits and starts operating the pump based on user history. They are however more expensive to install and service.

The initial installation cost of a full recirculating system is usually quite high if your house does not have a dedicated hot water return pipe to start with. The total cost could go all the wat to $1000 using a professional plumber. If you however decide to do it on your own, the cost of a hot water recirculating pump is $200-$250.

2. Recirculating Pump Comfort System


If you do not wish to install a dedicated hot water return pipe, this is the system to use. It is cheap to install and maintain but with its fair share of limitations.

A recirculating pump comfort system sends the unused hot water back to the water heater via the existing cold water line. You usually install the install the pump in the cabinet of the sink farthest from the water heater.

In order to install it, you will need to have a power outlet inside the sink cabinet. I should mention that this method is also for houses without a dedicated hot water return pipe. Newer houses will have a different design.

The whole pump assembly kit comes with the pump itself, a timer, 2 tees, 2 hoses and a check valve. The hoses and tees allow you to connect the cold and hot water lines via the pump while the check valve ensures water only flows in one direction to avoid a cross connection.

The timer will be installed on the side of the sink cabinet. You can also get a wireless remote-controlled timer to take with you around the house and turn on the pump as you wish.

If you have no power outlet under the sink, install the recirculating pump on the water heater’s hot water outlet. You will however need to shut off the water heater’s cold water supply and power/gas and then drain it.


If you live in areas with hard water, you need to be careful about the type of pump you install. A pump with a wider outlet and inlet will minimize the likelihood of calcium, iron and other mineral deposits clogging it.

A stainless steel pump will be pricier but worth it. As you select, make sure that you also factor in availability of parts. Recirculating pumps made in the United States are of superior quality and their parts are easily available.

The main disadvantage of this system is that since the unused cold water is usually sent back to the water heater using the cold water line, the initial flow of water from the cold line when you turn on the faucet will be lukewarm.

For most people, lukewarm water on the cold line is not an issue. It is perfect for washing hands, fruits and dishes. If you however drink water straight from your cold water line then this will be a problem.

Is a Recirculating Pump Worth It? Pros and Cons of Hot Water Recirculating Pumps

If you are looking at it from a return on investment (ROI point of view, a hot water recirculating pump will not save your money. The much it saves in water bills is utilized in power bills. What this pumps offers is convenience.

I know a lot of people who prefer to turn on the shower faucet, wait out the 60 or so seconds for the water to get hot and jump straight into the shower. This is especially the case if you live in a city, and are not on a septic system.

For folks on septic systems however, the less waste you send down the drain the better it is for you. If you have a septic system then a hot water recirculating system is then worth your while.

Another thing to not like about hot water recirculating pumps is the space taken under the sink. Most people use the area under the sink to store stuff. With a pump, extra hoses and electrical cables, the place just becomes untidy and its storage capacity greatly reduced.

I cannot forget to mention the noise. Pumps are noisy. Even if the pump will only be on for a few minutes, it is enough to bother some people. If you treasure silence at homes then these pumps are not for you.

The last thing I will mention is the running costs. Hot water recirculating pumps will need to be serviced from time to time. You will also need to replace them after a few years.

As you consider installing a hot water recirculating pump think about all these issues. If they don’t sound impressive to you, explore other alternatives to hot water recirculation systems.

Alternatives to Hot Water Recirculating Pumps

If recirculating hot water pumps are out of the question for you, there are other methods you can use to try and beat the hot way delay in your fixtures. Here are 2 of them:

1. Tankless Water Heaters.

Tankless water heaters or demand-type water heaters supply instant hot water whenever you need it. If the tankless water is however installed far from the fixtures, you will still have the hot water delay.

There are 2 options here. You can decide to install a new tankless water heater which comes with a hot water recirculating pump. For people who are looking to replace their tank-type water heater with a tankless water heater, this is the best solution.

Check out the signs that shows you need to replace your tank-type water heater in this post.

The second option is to install point of use tankless water heaters. These types of water heaters are usually installed close to the sink faucet or shower head. The only downside to this method is that you will need several of them, for each fixture.

The main advantage of tankless water heaters is power-efficiency. There is usually no water being heated when there is no demand for the water. Tank-type water heaters are always heating water and in the process consuming more power.

2. Pipe Insulation

Insulating your hot water pipes will prevent the exchange of heat between the hot water inside the pipe and the surrounding environment. This means that the unused hot water in the pipes will remain hotter for longer.

You can also insulate your hot water pipes even if you have a hot water recirculating pump. This will reduce the number of times that the water has to be cycled back to the water heater and in the process you will conserve energy.

A Good Hot Water Recirculation Pump

If you are looking for the best hot water recirculation pump in the market, I wouldn’t hesitate recommending the Grundfos 99452459 UP15-10SU7P/LC Instant Hot Water Comfort Recirculation Pump System. It is a little pricier than others in the market but the extra dollars are worth it.

This pump provides a retrofit solution, meaning you don’t need a hot water return line in your house. The complete kit includes a timer, 10 feet electrical cord, thermal bypass valve and 2 hoses.

Grundfos pumps are made of stainless steel for durability and has a battery back up to maintain its setting should you experience a power outage.

If you would be interested in the pump check it out here on Amazon.

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