Why Buying a Tankless Water Heater With a Recirculating Pump Makes Sense

Tankless water heaters have been popular in Europe for many years and are now becoming just as well-liked in North America. The on-demand style of water heating is attractive from the point of view you are not storing a large tank of water you've paid to heat and which slowly drops in temperature, especially at night when everyone's in bed, then you have to pay to heat the water again.

Tankless units are a fraction of the size of a traditional large tank water heater,  about the size of a large suitcase – and they can be wall-mounted to save floor space. Most manufacturers offer external and internal options.

They are super-efficient, and because they don't store vast amounts of heated water, they are considerably cheaper to run. Especially condensing models with the recirculation systems.

So is buying a tankless water heater with a recirculation pump a good idea?

Let's find out, shall we?

Tankless water heaterTankless water heater

Do tankless water heaters really deliver continuous hot water?

Continuous hot water is what you've dreamed about for decades, especially if you have a growing family with increasing demands on your hot water system as it tries to keep up. Tankless water heaters never run out of hot water, they keep on going no matter what you throw at them, and the last shower of the day is as hot as the first, every time. Great if you have a football team at home.

So what's not to like about tankless water heaters?

Not much, really, but we are hard to please bunch, and once we get used to our new tankless system and how cheap it is to run, how efficient it is never running short of hot water – what do we find to complain about now?

"It takes too long for the hot water to reach the faucet or shower, I have to wait minutes sometimes!"

Most of us would never have survived waiting for endless pans of hot water to be heated on the stove for our weekly tin bath, would we? Just like it was in the good ol' days.

We live in an "instant' world. Unless we get what we want NOW! It's just not good enough. So that has become a complaint about tankless water heaters.

Sorry - it's true, you do have to wait a few seconds

You do indeed have to wait a short time for the water heater to start delivering hot water to where you want it, but it's not so long, is it? If using tank-type, you also have to wait.

Your tankless water heater will deliver endless hot water, but continuous does not mean the same as instant. It is instant at the heater, but if you have a large property and there are bathrooms or sinks a long distance from your heater, the delay in getting hot water initially could be annoying.

The excessive waste of water is much more of an issue

However, the more significant issue is the amount of water wasted as it drains away while you wait for the correct temperature to arrive. It works out to be around 12,000 gallons of water a year for an average four-person home; that's a lot of wasted water as well as a serious concern.

If you are lucky enough to pull your water from a private well, it's probably free, so it's no big deal, but it's certainly not environmentally friendly. On the other hand, if you live with metered water, it has the added sting of higher water bills, and that's no fun at all, is it?

Has the problem been fixed?

To a degree, it has. By fitting a recirculation pump (available on amazon.com) to your tankless water heater, the hot water is sent very quickly to the point of use by a small pump, which can run continuously on a preset timer.

Alternatively, it can use remote switches and motion sensors, which trigger the pump when needed.

The downside is the best recirculation system needs a third dedicated pipeline, which takes the excess warm water back to the cold side of your heater, where it joins the circuit again. That way, the water loss is minimized dramatically, and the only additional cost is the power for a small pump, which is cheap to run. However, you will save cost because the warmer water returning to your heater will use less energy to bring it back up to temperature. So what's the problem?

The problem

The problem is in the cost of the dedicated return line. It's expensive to install, especially if it's retrofitted to an existing home. In a newly constructed home, it's not an issue; otherwise, it's a potentially costly and tricky job unless your home has spacious crawl areas under the floor and easy access everywhere to fit the pipe. It must also be fully insulated to conserve the heat that is costing you money.

So, there's a balance to be reached - the cost of wasted water versus the cost of installing a dedicated return line. That decision will depend on your specific circumstances and choices.

Is there an alternative?

There is an alternative. Instead of a dedicated return line, you can use your cold water line by installing a bypass valve at the sink or shower farthest from the heater. These valves close at a preset temperature, usually around 100 F, so anything colder than that will mix in with your cold supply on its way back to feed the water heater.

The only issue is your cold supply is no longer truly cold. It's mixed with excess warmer water, so the problem is reversed; you now have to run your cold faucet for some time to get cold water, which wastes water too.

Lukewarm water is perfectly acceptable for handwashing but very unpleasant to drink or clean your fruit with before you eat it.

So is a tankless water heater with recirculation worth it?

If you accept instant hot water could be too expensive an option for you, then perhaps on-demand water heating could be an excellent choice. It means you have to activate the pump or use motion sensors in each area where hot water is needed and accept there will be a very short delay in hot water reaching your faucet or shower. It's not an excessive wait, plus the water wastage is minimal.

The benefit is that your pump will only run as long as it's needed and will shut down when you stop drawing hot water, so you save power. It sounds like a good plan; you have hot water quickly where you need it, and you save on needlessly wasted water, plus the pump consumes so little power it's minimal. It's a great solution.

emergency plumber

Here's a bright idea!

One manufacturer has an intelligent design with a small buffer tank inside the tankless water heater… I know, I know we're going backward again, storing hot water… but wait…

The insulated tank is small and holds around five gallons of hot water in reserve so that when you draw water, you very quickly receive warm water, which becomes hotter faster, cutting your waiting time to a few seconds, and that is an ideal solution.

It's worth considering if you are in the market for a new tankless water heater with a recirculation pump.

Let's now look at three popular tankless water heaters with recirculation pumps built-in, which are on the market today.

3 top tankless water heaters with recirculation

Noritz NRCP111 tankless condensing water heater

  • Power - Minimum BTUh - 18,000 to maximum BTUh – 199,9000
  • Water flow - 0.5 to 11.1 GPM
  • Warranty – 15-years heat exchanger. 5-years parts. 1-year labor (residential only)
  • UEF Rating 0.94
  • Shower Rating: Southern Climate: 4 – 4.5; Northern Climate: 3
  • Quiet operation
  • The heater has a built-in recirculation pump, which is ideal with either a dedicated return line or a bypass valve. (Kit for the bypass version is available at additional cost).
  • The heat exchangers utilize heavyweight 304 stainless steel and copper for higher thermal transmission.
  • Low installation cost
  • By using a tankless water heater, you lower your carbon footprint.
  • There are no expensive, large tanks of hot water storage.
  • Noritz tankless water heaters last up to twice as long as regular water heaters.
  • An optional Wi-Fi connection is available.

Takagi TK-540P tankless condensing water heater

  • Power - Minimum 15,000 BTUh to maximum 199,000 BTUh
  • Water flow - Maximum of 10 Gallons Per Minute.
  • Warranty - 15-years heat exchanger, 5-year parts, 1-year labor (residential only).
  • UEF Rating of 0.93
  • Shower Rating: Southern Climate: 4; Northern Climate: 3
  • The unit has a built-in recirculation pump with either a dedicated return line or a bypass valve. 
  • The primary heat exchanger utilizes corrosion-resistant high-grade copper.
  • A secondary heat exchanger utilizes 316L stainless steel with high resistance against corrosion.
  • Condensing model for indoor use
  • Air-Fuel Ratio (AFR) sensor
  • Freeze protection
  • Overheat cut-off fuse
  • Water temperature & exhaust safety cut off

Rinnai RUR199 tankless condensing

  • Power - Minimum BTUh - 15,000 to Maximum BTUh - 199,000 
  • Warranty - 15-years heat exchanger, 5-year parts, 1-year labor (residential only).
  • Water flow - Maximum 10 GPM
  • UEF Rating of 0.93
  • Shower rating 5 – 7 depending on ground temperature
  • Quiet operation
  • Built-in Recirculation Pump with Rinnai ThermaCirc360™ technology, it delivers faster hot water with a timer and a bypass valve for installations with no dedicated return line.
  • WiFi Controller included
  • Rinnai has 50% Plus of the tankless water heater market in the USA.
  • Tankless water heaters will last 15 to 20 years.
  • Touchpad indicates when there's a buildup of limescale or calcium on the heat exchangers.
  • Touchpad remotes around your home allow you to select multiple individual temperatures at points of delivery.
  • Preset your required temperature, and the tankless water heater will deliver only hot water at that temperature.
  • Never run out of water again. When you are not using hot water, they consume no power at all.
  • Linkable unit for substantial homes, you can link several Rinnai tankless water heaters together.


Tankless water heaters are an excellent choice for on-demand water heating and will deliver endless hot water in your home; you will never run out.

They are more expensive to buy and install and have to be fitted by trained professionals, but the savings you will get in your energy costs for heating water are significant. They will potentially deliver savings of between 8% and 14%, and if you use more than 86 gallons a day, your savings could be between 27% and 50%.

Buying a unit with a recirculation pump will get you closer to the dream of 'instant' hot water throughout your home, and it's worth it.

Take a look at the Energy Saver 101: Water Heating infographic to help you decide if a tankless water heater with a recirculation pump is right for you, then go buy one!