Water Heater Circulation Pump: What You Need To Know

Circulation Pump

Are you considering installing a circulation pump to your water heater? This simple device can not only save you money, 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. 

What Does a Circulation Pump Do?

How your home plumbing works without a circulation pump
  1. When a hot water tap is closed, the water flow stops. 
  2. When no hot water is needed the water sits within the pipes and cools.
  3. 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.
  • The bottom line: There is 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!
How your home plumbing works with a circulation pump
  1. Once the hot water tap is closed the hot water will stop temporarily at the tap before it begins to circulate thru the houses plumbing again.
  2. When no hot water is needed the water within the pipes circulates on a continuous basis in preparation for the next hot water demand.
  3. When the hot water tap is opened, hot water is delivered nearly immediately.
  • Bottom Line: When a hot water tap is opened water is hot, saving time and money.

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.

The Pro's 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.

Here are a few of the benefits:​

  • Ease of Installation - Circulation pumps are fairly easy to install. No special permits or tools are usually required, and there are many models 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.

The Con's of Installing a Circulation Pump

Who doesn't want to have hot water on-demand and save both time and money? Although, keep in mind that every good thing usually has a few drawbacks. 

Here are a few of the drawbacks:

Heat Loss - There can be a significant amount of heat loss from your home's plumbing. As hot water is circulating thru 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. 

Types of Pumps

There are 3 main types of circulation pumps.

1. 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, it is returned back to the water heater.

Since this basic system is running continuously, it places a tremendous amount of unnecessary wear on your water heater. We do not recommend this type of system. 

2. 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. ​

These systems tend to be a little more expensive and can range in price from three to six hundred dollars depending on the size of your house.

  • 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.

3. 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.

You can expect to pay around $300 for this type of system. ​

  • 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.

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.​