| A circulator pump is a specific type of pump used | | | | in added energy use. In typical one-way plumbing |
| to circulate gases, liquids, or slurries in a closed | | | | without a circulation pump, water is simply piped |
| circuit. They are commonly found circulating water | | | | from the water heater through the pipes to the |
| in a hydronic heating or cooling system. Because | | | | tap. Once the tap is shut off, the water remaining |
| they only circulate liquid within a closed circuit, | | | | in the pipes cools producing the familiar wait for |
| they only need to overcome the friction of a | | | | hot water the next time the tap is opened. By |
| piping system (as opposed to lifting a fluid from a | | | | adding a circulator pump and constantly circulating |
| point of lower potential energy to a point of | | | | a small amount of hot water through the pipes |
| higher potential energy). | | | | from the heater to the furthest fixture and back |
| Circulator pumps as used in hydronic systems are | | | | to the heater, the water in the pipes is always |
| usually electrically powered centrifugal pumps. As | | | | hot, and no water is wasted during the wait. The |
| used in homes, they are often small, sealed, and | | | | tradeoff is the energy wasted in operating the |
| rated at a fraction of a horsepower, but in | | | | pump and the heat lost from the constantly-hot |
| commercial applications they range in size up to | | | | pipes. Thermal insulation applied to the pipes helps |
| many horsepower and the electric motor is | | | | mitigate this second loss and minimize the amount |
| usually separated from the pump body by some | | | | of water that must be pumped to keep hot |
| form of mechanical coupling. The sealed units used | | | | water constantly available. |
| in home applications often have the motor rotor, | | | | The traditional hot water recirculation system |
| pump impeller, and support bearings combined and | | | | uses a dedicated return line from the point of use |
| sealed within the water circuit. This avoids one of | | | | located farthest from the hot water tank back to |
| the principal challenges faced by the larger, | | | | the hot water tank. In homes where this return |
| two-part pumps: maintaining a water-tight seal at | | | | line was not installed the cold water line is used as |
| the point where the pump drive shaft enters the | | | | a return line with a temperature control device |
| pump body. | | | | closing the connection between the hot and cold |
| Small- to medium-sized circulator pumps are | | | | lines at a set temperature. Compared to a |
| usually supported entirely by the pipe flanges that | | | | dedicated return line, using the cold water line as a |
| join them to the rest of the hydronic plumbing. | | | | return has the disadvantage of heating the cold |
| Large pumps are usually pad-mounted. | | | | water pipe (and the contained water). |
| Pumps that are used solely for closed hydronic | | | | Technological advancements within the industry |
| systems can be made with cast iron components | | | | allowed for incorporating timers to limit the |
| as the water in the loop will either become | | | | operations during specific hours of the day to |
| de-oxygenated or be treated with chemicals to | | | | reduce energy waste by only operating when |
| inhibit corrosion. But pumps that have a steady | | | | occupants where likely to use hot water. |
| stream of oxygenated, potable water flowing | | | | Additional advancements in technology include |
| through them must be made of more expensive | | | | pumps which cycle on and off to maintain hot |
| materials such as bronze. | | | | water temperature versus a continuously |
| Use with domestic hot water | | | | operating pump which consumes more electrical |
| Bronze pumps are often used to circulate | | | | energy. Utilizing "normally closed" crossover valves |
| domestic hot water so that a faucet will provide | | | | have been shown to further reduce energy |
| hot water instantly upon demand. In regions | | | | consumption by preventing undesired siphoning of |
| where water conservation issues are rising in | | | | water from a hot water line during cold water |
| importance with a rapidly expanding population, | | | | usage which lowers the cold water lines water |
| and a record economic expansion that has | | | | pressure allowing the higher pressured water in |
| consumers looking for comfort, so-called Hot | | | | the hot water lines to pass through a "normally |
| Water Recirculation (HWR) pumps can aid in | | | | open" crossover valve increasing the energy |
| water conservation at a relatively small expense | | | | demand on the water heater. |