Circulator pump

A circulator pump is a specific type of pump usedin added energy use. In typical one-way plumbing
to circulate gases, liquids, or slurries in a closedwithout a circulation pump, water is simply piped
circuit. They are commonly found circulating waterfrom the water heater through the pipes to the
in a hydronic heating or cooling system. Becausetap. 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 ahot water the next time the tap is opened. By
piping system (as opposed to lifting a fluid from aadding a circulator pump and constantly circulating
point of lower potential energy to a point ofa 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 areto the heater, the water in the pipes is always
usually electrically powered centrifugal pumps. Ashot, and no water is wasted during the wait. The
used in homes, they are often small, sealed, andtradeoff is the energy wasted in operating the
rated at a fraction of a horsepower, but inpump and the heat lost from the constantly-hot
commercial applications they range in size up topipes. Thermal insulation applied to the pipes helps
many horsepower and the electric motor ismitigate this second loss and minimize the amount
usually separated from the pump body by someof water that must be pumped to keep hot
form of mechanical coupling. The sealed units usedwater constantly available.
in home applications often have the motor rotor,The traditional hot water recirculation system
pump impeller, and support bearings combined anduses a dedicated return line from the point of use
sealed within the water circuit. This avoids one oflocated 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 atline was not installed the cold water line is used as
the point where the pump drive shaft enters thea return line with a temperature control device
pump body.closing the connection between the hot and cold
Small- to medium-sized circulator pumps arelines at a set temperature. Compared to a
usually supported entirely by the pipe flanges thatdedicated 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 hydronicTechnological advancements within the industry
systems can be made with cast iron componentsallowed for incorporating timers to limit the
as the water in the loop will either becomeoperations during specific hours of the day to
de-oxygenated or be treated with chemicals toreduce energy waste by only operating when
inhibit corrosion. But pumps that have a steadyoccupants where likely to use hot water.
stream of oxygenated, potable water flowingAdditional advancements in technology include
through them must be made of more expensivepumps which cycle on and off to maintain hot
materials such as bronze.water temperature versus a continuously
Use with domestic hot wateroperating pump which consumes more electrical
Bronze pumps are often used to circulateenergy. Utilizing "normally closed" crossover valves
domestic hot water so that a faucet will providehave been shown to further reduce energy
hot water instantly upon demand. In regionsconsumption by preventing undesired siphoning of
where water conservation issues are rising inwater 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 haspressure allowing the higher pressured water in
consumers looking for comfort, so-called Hotthe hot water lines to pass through a "normally
Water Recirculation (HWR) pumps can aid inopen" crossover valve increasing the energy
water conservation at a relatively small expensedemand on the water heater.