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Water Heater Circulation Pump: What You Need To Know

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Are you considering installing a circulation pump to your water heater? This simple device will not only save you money, but it can also deliver nearly instant hot water. A circulation pump keeps the hot water constantly moving through the home's plumbing system, so when a hot water tap is opened, the water will be hot right away.

A circulation pump will help your water heater deliver hot water incredibly fast. That's why its critical that you keep your heater in peak condition and perform water heater maintenance tasks on a regular schedule. We also highly recommend installing a sediment filter to your incoming water line.

What Does a Circulation Pump Do?

When you have a circulation pump installed, hot water is circulationg throughout your plumbing in order to speed the delivery. Let's take a closer look at what happens when you have a circulation pump installed and when you do not. 

Plumbing WITHOUT a Circulation Pump Installed

If you don't have a circulation pump installed, this is how your home plumbing works:

  • When a hot water tap is closed, the water flow stops.
  • When no hot water is needed, the water sits within the pipes and cools.
  • When the hot water tap is once again opened, the cool water that has sat stagnate within the plumbing needs to be "pushed" thru the pipes before the hot water from the water heater reaches the tap.

Bottom Line

There's a lot of wasted water going down the drain. 

Over the course of a year, this can add up to hundreds of gallons of water!

Plumbing WITH a Circulation Pump Installed

If you have a circulation pump installed in your home, this is what happens:

  • Once the hot water tap is closed, the hot water will stop temporarily at the tap before it begins to circulate through the plumbing again.
  • When no hot water is needed, the water within the pipes circulates on a continuous basis in preparation for the next hot water demand.
  • When the hot water tap is opened, hot water is delivered nearly immediately.

Bottom Line

When a hot water tap is opened, the water is hot right away.

This saves both time and money!

Pros and Cons of Hot Water Recirculating Pumps

However, for all of the advantages a circulation pump offers, there are also a number of things you should consider before buying and installing one.

Pros of Installing a Circulation Pump

Circulation pumps aren't new. They have been used in restaurants and high-end hotels for years. But it hasn't been until relatively recently that homeowners have been able to take advantage of the convenience and savings.

  • Ease of Installation - Circulation pumps are fairly easy to install. No special permits or tools are typically required. There are many models available designed specifically for home plumbing systems.
  • Selection - There are many manufacturers and options available.
  • Convenience - Hot water is available nearly immediately when a tap is opened. The convenience of having nearly instantaneous hot water is a huge draw for home owners.
  • Ease of Operation - Most units are very easy to operate. Once they are set you seldom need to make any adjustments.
  • Water Usage - Less water is wasted since hot water is delivered nearly immediately. In areas where water is in short supply this is especially helpful. A significant amount of water can be saved every year.

Cons of Installing a Circulation Pump

For all the benefits a circulation pump offers, it also has a few drawbacks:

  • Heat Loss - There can be a significant amount of heat loss from your home's plumbing. As hot water is circulating through your pipes, heat is lost while it is waiting to be used. Although, you can minimize the loss by insulating your hot water pipes. 
  • Initial Cost - Expect to pay a few hundred dollars for a quality pump. There are less expensive pumps available, but purchasing a high-end model is a good idea and a worthwhile investment.
  • Power Consumption - Circulation pumps have come along way in improving the amount of power needed. Many of the early units ran non-stop using more electricity and placing demands on your water heater 24/7. Today, most pumps are designed to strike a balance between conserving energy and meeting hot water demands. 
  • Noisy. Older and cheaper models can add some extra noise to your regular water heating. 

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Types of Circulation Pumps

There are 3 main types of circulation pumps. Let's take a closer look at each:

Basic Circulation Pump

This System uses a small pump that is constantly circulating water thru the home's main water lines, also known as trunk lines. If the water isn't used, its returned back to the water heater.

Grundfos 98420224 Comfort PM AutoAdapt Recirculation Pump NPSM, 1 1/4-Inch

Grundfos Comfort PM

The Grundfos Comfort PM is an excellent example of a basic circulation pump.

On-Demand Circulation Pump

An on-demand system operates when there is a demand for hot water. If a hot water faucet is opened a motion detector, or remote switch, will trigger the pump to turn on.

Once the pump turns on, it will continue to circulate the water thru the pipes until the water reaches a set temperature. 


  • There's an option to override the motion detector so the pump can be manually activated.
  • Hot water is delivered quickly, saving time, water and money.
  • An On-Demand system can reduce the energy demand of your water heater, therefore, saving money on your utility bills.
  • For retrofitted homes, the crossover of hot water into the cold water plumbing will be reduced.


  • Hot water is not delivered instantaneously because the pump will need to activate.
  • The way your house is plumbed will determine the amount of time needed to deliver hot water.
  • For retrofitted homes, a power source and a pump will need to be used at each hot water loop.
BACOENG 3/4'' 110V RS15/6G 3-Speed Control Hot Water Circulation Pump/Circulating Pump With US Plug and Flow Switch

Bacoeng Recirculating Pump

On-demand circulating pumps offer many advantages over the basic models. 

Time and Temperature Circulation Pump

A Time and Temperature system allows you to program the pump to match your hot water needs. You can set the adjustable timer and aquastat to the times you'll need hot water. For example, if you always take a shower at 7am and run the dishwasher at 8:30am, you may want to set the pump to cycle on at 6am and cycle off at 10:30am.


  • The pump settings can be adjusted easily.
  • Both the time and temperature settings need to be triggered for the hot water to circulate thru your plumbing.
  • Settings can be easily overridden if needed.
  • Hot water is nearly instantaneous, saving time, money and water.


  • This system can increase your energy usage if it's overused.
  • Retrofitted homes could experience issues at the faucet farthest from the water heater. Occasionally, the cold water lines could be heated.
Watts 500800 Instant Hot Water Recirculating System with Built-In Timer, Easy to Install

Watts Recirculating Pump

Time and Temperature circulating pumps allow you to dial in exactly when you want hot water.

Retrofitting Your Home

When a home is plumbed for a circulation pump there is a dedicated return line. This line sends the hot water back to the water heater to bring it back up to temperature.

Houses that are retrofitted do not usually have a dedicated return line. However, a crossover valve can be installed under the sink that is the farthest away from the water heater. This configuration uses a Time and Temperature Circulation Pump. 

Crossover valves open when the hot water temperature falls below 95 degrees Fahrenheit. When the valve opens the cool hot water is allowed to flow into the cold water line until the water in the hot water line reaches 105 degrees Fahrenheit. Once the hot water reaches 105 degrees, the valve closes. 

Keep in mind that when the crossover valve is open, the warm water is flowing into the cold water line. This will likely cause the cold water to be warmer than normal.

The Time and Temperature system is a very common circulation pump. They have many benefits and are very convenient. However, when it comes to retrofitting your home, the On-Demand system is a bit easier to install.


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