Hot Water Recirculating Pumps Explained: Why, How, Costs (+Tankless)

When you turn on the shower or a faucet, do you get hot water instantly? Not really. It can take anywhere from 10 seconds to 1 minute for the hot water to reach the faucet. To reduce that time significantly (and stop needlessly wasting water), we can install hot water recirculating pump.

Here’s the deal on how to get the hot water faster from a water heater:

When we turn on any faucet, the hot water needs to travel from the hot water heater to the faucet. It is propelled only by water pressure. If you add a powerful hot water circulation pump at the heater (not under the sink), the hot water will reach the faucet much faster. By installing a hot water circulation pump, you will have a hot shower right away.

recirculating pump installed on a water heater for quick hot water
Watt recirculating pump installed on the water heater (pump plugged into standard 110/120V outlet, 3/4-inch pipe thread connectors, valve).

On top of that, the recirculating pumps also return the cold water in the pipes back to the heater. This serves two functions:

  1. You save water. All that water spend waiting for the hot water to finally kick in is not wasted anymore. In the brochure for Watt hot water recirculation pump, you might see something like ‘Watt circulation pump can save you up to 12,000 gallons of water per year’. That would be about $2,160 per year. Realistically, you can easily save a couple of $100s per year. According to Oak Ridge National Laboratory, an average person wastes 1-3 gallons of water per day just waiting for the hot water to start flowing. We will use these numbers to determine how much do you really save with recirculation pumps.
  2. Get hot water quickly. The water pipes are now empty. When you will need hot water, the hot water won’t have to push against cold water. Now, it will push against air alone, and it will arrive at the faucet in no time.

This is also true for tankless water heaters. These on-demand units need an even longer time for the hot water to reach a faucet because the heater has to first heat the water and then send it along to the faucet. There are special tankless water heater recirculation pumps for Navien, Rinnai, and Rheem units; we will cover them all.

Here we will cover all the important parts of hot water recirculations pumps, including:

  • How do hot water recirculation pumps work to get hot water fast?
  • What parts does a home water recirculation pump include, and where to install it.
  • Types of water circulation pumps, including tankless water heater recirculation pumps.
  • Advantages and disadvantages of hot water circulation pumps.
  • Costs associated with hot water circulation pumps (parts + installation + DIY savings).
  • Note on tankless hot water heater recirculation pumps (double trouble solved).

You will get an overall look at how you can use increased water pressure by a circulation pump for almost instantaneous hot water access.

Quick summary on costs: Recirculating a pump is certainly useful if you want hot water quickly. It does save you water but it also costs you a bit of electricity. We’ll tackle the installation and running costs of a circulating pump in full near the end.

Let’s start by looking at how these pumps actually work:

How Does A Hot Water Recirculation Pump Work?

If it takes ‘forever’ for the hot water to start running, it usually means that there is a long pipe between a boiler (or a hot water heater or tankless water heater) and the faucet. The bigger the house, the longer these water pipes usually are, and the longest it takes to get hot water.

The hot water recirculation pump works by:

  1. Increase water pressure at the water heater. This propels the water to your faucet or shower much quicker.
  2. Returns the unused hot water in the pipe back to the water heater or boiler.
  3. Empties the water pipes so the next time you’ll need hot water fast, it will meet less resistance in the piping and it will arrive at the faucet in a matter of seconds.

The very phrase ‘recirculating’ comes from this pump returning the unused hot water back into the tank. This is done every time you close the faucet. It is important to note that recirculation pumps don’t work continuously; they are used only when we open and close the faucet.

Now, when installed, the recirculating pump makes it seem that the hot water starts flowing right away like magic. In fact, however, the whole machinery of the hot water recirculating pump has to be activated for this to happen.

Let’s look at the individual parts that make up the recirculation pump for hot water:

What Parts Are In The Hot Water Circulation Pump Kits?

If you want to install a recirculation pump, you start by getting the whole recirculating pump kit. You can install it yourself (DIY circulation pump installation) or call a professional; more on that in the part about how much do hot water recirculating pumps cost.

Here is the list of all the parts you need to install a recirculation pump. Of course, the most important part is the pump itself, so we’ll start with that:

  • Electric Pump. This is a standard impeller-style pump with 110/120V (you can plug it in in any standard outlet). Depending on the size of the pump, it can generate 0.22-3 amp; that means it runs on anywhere from about 20W to 360W. All that power is used to move water into and out of your existing pipes. To connect with your piping, every recirculating pump has 3/4 pipe thread connectors.
    watt hot water recirculation pump kit with parts explained
    All the necessary hot water recirculation pump kit parts.
  • Pipe Thread Connectors. These are 3/4 inch connectors that connect the electric pump to your existing piping.
  • Check Valve. Every hot water recirculation pump (even tankless water heater circulation pumps) is required to have a check valve. Check valve ensures that the flow of water is in the right direction.
  • Timer and Temperature Sensor. Both are used to increase the energy efficiency of hot water recirculation pumps. Times can be programmed for the pump to come on when you need more hot water (usually in the evenings; showering). The temperature sensor measures the water temperature and shuts the pump off when the water is hot enough. Only the energy-efficient hot water recirc pumps have these two (they don’t have to be used in tankless water heater recirculation pump systems; tankless hot water heater usually already has them).

These are the standard building blocks of every recirculation pump for getting hot water quickly. Parts that will actually be used depend on what kind of hot water recirculation pump you have. Let’s look at the two most popular types:

2 Types Of Hot Water Recirculation Pumps Used In Homes

You can install hot water or tankless hot water recirculation pump in an existing or in a new home. The major difference with hot water pumps in new homes is that you can install a full recirculation pump system (Type #1). This requires the installation of an additional water pipe.

In existing homes, adding an additional pipe for a full recirculating pump system is often too expensive; it’s just don’t worth it, according to HVAC specialists. That’s why most homeowners prefer installing the recirculation pump without the extra pipe. This is known as recirculating home pump comfort system (Type #2) and it’s the most popular way to get hot water quickly.

Type 1: Full Recirculation Pump System

When building a house, it’s smart to think about hot water recirculation as well. To install a full recirculating pump system, you need to consult with a plumber because you will need an extra pipe.

This extra pipe is installed parallel to conventional piping. With two pipes, you can create a loop between the water heater and faucets. The electric recirculation pump uses this other pipe to pump the hot water back into the boiler or water heater.

Obviously, you might be wondering: If the recirculation pump loop is running continuously, you’re probably expanding too much electricity just to get hot water faster.

This is where the timer and temperature sensor come in. To create an energy-efficient full recirculation system, your pump has to come with these two efficiency optimizing parts.

The timer has control over when the pump is working continuously. You can set it to run in the morning before work, and in the evening. You can turn it off during work hours, over the night, when you go on vacations, and so on.

The temperature sensor, on the other hand, makes sure you don’t needlessly use too much energy to heat the water. When the water is sufficiently hot, the temperature sensor will shut off the power to the recirculation pump to conserve energy.

This type of hot water recirculation system is most appropriate for new homes; homes that are in the 3rd or 4th part of the building process.

For most existing homeowners, integrating a recirculating home pump comfort system on top of the existing piping makes much more sense:

Type 2: Recirculating Home Pump Comfort System

Here’s why this is the most popular type of hot water recirculating pump in homes:

You use the existing water pipe alone. You don’t have to install an additional pipe. The pump works on the existing pipes; it basically sends the leftover water back to the boiler or the heater.

This is the system you can see in the photos above. The recirculation pump is fixed on the water heater. The 3/4-inch pipe thread connectors are used to connect the pump to your existing pipes.

Without the need for extra piping, this type of hot water circulation pump system also comes at a much lower cost. Depending on the size of the pump and installation difficulty, the average cost of a hot water recirculation pump costs anywhere from $200 to $800 (installed).

Quite surprisingly for most homeowners, the biggest problem with this type of recirculation pump is getting cold water. Here’s the thing: Both cold and hot water need to be supplied using the same pipe. That means that the cold water is not actually cold; it will usually be slightly warm (at room temperature). That may present a problem in the summer when you need cold water; turning the pump off during the summer months solves the problem.

Both types of systems have similar pros and cons. Let’s outline them here:

Advantages And Disadvantages Of Hot Water Recirculation Pumps

To determine if installing a hot water recirculation pump makes sense for your situation, we have to check the pros and cons. Obviously, everybody loves immediate hot water from their faucets but this luxury can be quite expensive.

Let’s start with the positive aspects:

6 Pros Of Hot Water Circulation Pumps

The whole point of installing such a pump is to get hot water fast. Nobody really likes waiting for the hot water to start flowing under the shower or doing the dishes, for example.

Here is a list of advantages associated with hot water circulating pumps:

  • Instant Hot Water In Any Faucet. This is the No. 1 reason why people decide in favor of hot water pumps. Without a pump, you have to wait for at least 10 seconds or up to 1 minute for the hot water to start flowing. The main advantage of hot water recirculation pumps is that you get hot water quickly to any faucet in your home.
  • Save Water. While you’re waiting for the hot water to hit your faucet, a lot of cold water is wasted. In a year, you might be wasting 1,000s of gallons of water. Most pump producers claim that installing a hot water recirculation pump can save you up to 12,000 gallons of water. According to Statista, a family of 4 will use about 400 gallons of water per month; that costs $72.93/month or $0.18 gallon. If you were to save 12,000 gallons of water per year, that would save you about $2,160 per year. Realistically, you won’t save that much, but the water savings with recirculation pumps can easily reach a few $100s per year.
  • Save Money. All the water savings, as we see, result in recirculation pumps saving money. We will do the cost analysis if the recirculation pumps are worth the money in the next chapter.
  • Easy Installation. It’s quite common to DIY hot water recirculation pumps. It will take about an hour but you can fully do it yourself, without the need to pay extra money to a plumber.
  • No Permits Requires. On many occasions, you will need state-mandated permits to make bigger changes to your piping system. Hot water recirculation pumps can be installed without a special permit from the state.
  • Safe To Use. Everything runs on electricity, and electricity is much safer than gas or propane additions to the existing piping system.

Now let’s have a look at the disadvantages of these pumps:

4 Cons Of Hot Water Circulation Pumps

Needless to say, recirculation pumps are not free. The upfront cost is a major deterrent when deciding if it makes sense to install a circulation pump or not.

Here is the summary of all the negative aspects of hot water circulation pumps:

  • Upfront Cost. The parts (electric pump, valve, 3/4-inch thread connectors) run at a couple of $100s. There is just no avoiding that. What you can avoid are installation costs. According to Fixr, hiring a plumber realistically costs between $75 and $130 an hour. An experienced plumber will have the whole recirculation pump installed and ready to use in less than 30 minutes. You can also do the installation yourself and reduce the upfront costs.
  • Running Costs. Every hot water recirculation pump runs on electricity. If you take into account that pumps run on 40W on average, running it for a full year non-stop 24/7 will use 350.4 kWh. The average price of electricity is $0.1319 per kWh. That means the running cost of such a hot water recirculation pump is $46.22/year.
  • Lukewarm Water (No Cold Water If Pump Is On). Since both the cold and hot water use the same pipe, you will have difficulty getting really cold water. That’s not ideal in the summer; you can always turn the pump off and you’ll get the cold water as per usual.
  • Outlet Requirements. The electric pump requires a 110/120V outlet. If you don’t have such an outlet near your water heater or boiler. If you don’t have one, you will have to use cord extensors to get it there.
  • Problems With Sensor Valves. Sensor valves are prone to inaccuracies. You might have to change it from time to time. They are cheap but you have to have it on your mind and that’s not positive at all.

How Much Do Hot Water Circulation Pumps Cost + Installation Cost + Running Cost? (With Water Savings Analysis)

Are circulation pumps worth it?

This is the key question. Are these pumps just a luxury that enables you to get hot water lightning fast, or do they actually save you money?

Let’s first figure out the costs:

  • Cost Of Recirculation Pump Kit. With these kits, you can install the pump yourself. They can cost anywhere from $100 to $500. Here is one of the most popular home recirculation pumps as an example (costs about $170):
    cost of hot water recirculation pump with timer
    This is the ‘Watts Premier Instant Hot Water Recirculating Pump System with Built-In Timer’. It’s very popular because you can install it yourself. You can check its price and get it here.
  • Installation Cost. As we have figured out in the previous chapter, it will take an experienced plumber who works for $75 to $130 an hour about half an hour to install. In most cases, the cost of installing a hot water recirculation pump runs at less than $100.
  • Running Electricity Costs. Are hot water recirculation pumps expensive to run? Not really. We have calculated that if you run a 40W unit non-stop 24/7, you’re looking at a $46.22/year extra in electricity bills (at a national average electricity cost of $0.1319/kWh).

Now, we have to check if these costs are balanced out by the water savings. We will presume that you’re buying a hot water circulation pump for a household of 4 and that each person wastes about 2 gallons of water per day (mean value of Oak Ridge National Laboratory’s study).

That means that this household wasted 8 gallons of water per day just waiting for hot water. That’s 2,920 gallons of water per year wasted.

How much is that in water bills?

If we take that the average price of water is $0.18/gallon (according to Statista’s 2019 study), here’s how much you can save on water with a recirculation pump:

Water Savings = 2,920 gallons/year * $0.18/gallon = $525.60/year

Those are quite significant savings. That means that all the costs of the hot water circulation pump are covered by the water savings. What is more, you can, by these estimates, reduce the future water bill considerably and actually profit nicely just by not needlessly waiting for water when you’re waiting for the hot water to kick in.

Note On Tankless Water Heater Hot Water Recirculation Pumps (Double Trouble)

Having a tankless water heater is an energy-efficient way of getting hot water. However, if you want hot water fast, these on-demand heaters are not ideal.

In fact, with a tankless water heater, you face double trouble (that’s why you’re not getting hot water fast):

  1. Cold Water In Pipes. As with tank water heaters, the cold water in the pipes has to be emptied first. Only after you stand there running a faucet for some time does the hot water start flowing.
  2. Tankless Heater Has To Heat Up Water. In tankless water heaters, hot water is not readily available as with standard tank heaters (with boilers). A tankless heater needs to first heat up water – it does that remarkably fast but not instantaneous – and that adds some seconds to our wait time in front of the faucet.

Because we need to wait longer for hot water in the case of tankless water heaters vs. traditional water heaters, it makes sense to minimize that time in tankless heaters even more.

There are two options when it comes to tankless heaters and recirculation pumps:

  1. Get A Tankless Water Heater With A Recirculation Pump. Because the circulation pump is such a desirable feature, companies like Navien, Rinnai, and Rheem started including the circulation pump in these on-demand water heaters. We talk about tankless water heaters with a built-in recirculation pump. Be aware that the inclusion of a pump increase the price of a tankless water heater by as little as $200 and as much as $500
  2. Get A Tankless Water Heater Circulation Pump Kit. If you already have a tankless unit without a pump, you can get the pump kit and install it. This is harder to install by yourself; you’re advised to call a plumber to help you out with the installation.

If you have difficulty finding out which brand is the best for a tankless water heater with a recirculation pump, you should check the newest Navien, Rinnai, and Rheem units. These are the 3 most often recommended brands for tankless water heaters with recirculation pumps.

All in all, it’s important to understand that recirculation pumps are worth the money. They are not without upfront costs or disadvantages, but they do offer the luxury of having hot water almost instantaneously and they save you a lot of water. Eventually, they pay for themselves by reducing the water bills.

If you have any questions about these pumps, how they work, or some calculations, you can give us the specifics in the comments below and we’ll try to help you out.

23 thoughts on “Hot Water Recirculating Pumps Explained: Why, How, Costs (+Tankless)”

  1. Great article!! but you stopped short for me. I’m interested in information on a tankless water heater with a built in recirculating pump. Your article ended saying “All in all, it’s important to understand that recirculation pumps are worth the money. They are not without upfront costs or disadvantages…”. What disadvantages, beside cost???? Thanks!

    • Hello David, well, the additional costs are a con here. The disadvantages of recirculating pumps include waiting for cold waters (it’s a less-known disadvantage), having to install additional wiring, and so on. We always take the pros vs. cons approach because nothing is perfect.

  2. You mentioned that in the summer months your can turn off the recirculation pump. Can you turn it off in a tankless that has it built in?

    • Hello Lucy, in most cases, you have that option. Some brands/models don’t include it. You can crack open the manual for your tankless heater and check if it comes with that option.

  3. Is there a recirculating pump for the tankless water heater known as Trutankless?

    It would be nice to get the hot water to the faucet especially the shower in the morning as quickly as possible

    • Hello Irving, Trutankless is an Arizona-based brand of tankless water heaters with built-in recirculation pumps. So, there is such a thing.

  4. We have one faucet in the kitchen that has instant scalding hot water the second you turn it on . We were advised of this upon installation. Can this be moved to another sink in the house that is not used as often ?

    • Hello Sam, you can shut off the recirculating pump to the kitchen faucet. For moving the pump to another sink, you would have to talk with a plumber. It depends on how the recirculation pump is installed, and some other factors, plumbers usually know this stuff pretty well.

  5. I have a new Noritz tankless water heater that includes an AquaMotion recirculating pump at the heater and a crossover valve under the kitchen sink. This time of year, we don’t need to have instant hot water circulating so we turned “off” the pump. However, whenever I turn on the cold water at the kitchen sink for a few seconds the tankless unit starts to run (heat water) even though I don’t want heated water. Is this a common drawback with the under-sink crossover valve?

    • Hello Frank, one of the disadvantages of recirculating pumps is that you have to wait for cold water a bit. However, that shouldn’t happen if you have turned the pump off. This might be a small installation error or a faulty setting. It’s not exactly normal.

  6. Hi:
    The second method seems to suggest the cold water at sinks will most likely have been run through the hot water tank. After draining a few hot water tanks over the years, removing sediment, will the cold water now possibly have some sediment and/or taste issues.

    • Hi Patrick, that’s a good insight. The short answer is ‘no’, your water will still be pure. There are filters that prevent the sediment from entering the water flow. But, yes, I understand why it seems feasible for the sediment to eventually enter the water flow and cause the change in taste of water.

    • Hi Howy, well, the circulating pumps are usually powered by electricity, so they don’t use gas. However, some gas needs to be used to heat water for the pump to circulate; the gas usage for this is pretty much insignificant relative to how much gas we use when powering the instant hot water heater.

  7. I have a tankless water heater with an external recirculating pump at the heater and a crossover valve under the kitchen sink. This time of year, we don’t need to have instant hot water circulating so we turned “off” the pump. However, whenever I turn on the cold water at the kitchen sink the tankless unit starts to run (heat water) even though I don’t want heated water.
    Is this a common drawback with the under-sink crossover valves, for the heater to turn on when a cold water faucet is turn on?

    • Hi Mike, we think about water as hot vs. cold. Water heaters think about water in temperature: If the inlet water temperature is 40°F and the guy at the kitchen sink doesn’t want his hands to freeze, I need to warm that water up to 55°F. That’s kind of why the water heater still has to do some work (it turns on); it’s not a lot of heating but some heating is usually required. Hope this illustrates well why this might be occurring; it’s a pretty standard thing.

  8. Can a Hot Water Recirculating Pump cause low water pressure? I noticed my apartment building installed one and at that time the whole water pressure was low.

    • Hi Christopher, not really. Water recirculating pumps just circulate the water; the water pressure should stay the same. When you are installing water system stuff, a lot of things can cause low pressure.

  9. Hi,
    We are considering getting a 27kW tankless heater for a “summer home” (rented out for about eight weeks per summer) that needs to be fully winterized each November. With a tankless water heater, can it be completely drained, and can all the pipes in the house be completely drained as well (typically done with an air compressor/antifreeze, etc.) Last winter there was a two- week period with windchill bringing temps down to 41 below zero.

    • Hi Joyce, a very good question. All tankless water heaters and the pipes can be drained (quite a useful thing to do if you don’t use it and the temperatures go down to -41F). To drain the heater turn off the power/gas supply, shut off the water supply valve. Check where your drain valve it; attach a hose and let the water out. Then you can drain the pipes with the air compressor or antifreeze. Hope this helps.

  10. One thing I’m doing with a smart home is. I’m putting an occupancy sensor in all the usage areas. And when someone enters one of these usage areas. It starts flashing a yellow LED and then when it gets hot water to that location. It turns off the pump and flashes a yellow LA D for a while. This way. You only run the hot water pump when you need hot water

  11. Wonderful information for me. I had tankless water heater installed that runs off of propane and your info has helped me better understand the recirculating pump installation. I have a Rinnai not sure if it came with pump. It’s less than a year old. Gotta check. Anyways thank y’all.


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