PlumbingProducts.com Our goal is to provide visitors with excellent plumbing how to's and other great plumbing-related articles.
Kitchen related articles Bathroom related articles Commercial related articles Misc articles Favorite links

Hot Water Re-Circulation Systems

Want To Learn More About Re-Circulation Systems?
re-circulation The hot water line in your home carries hot water from the water heater to the different sinks, baths, and showers in your home. Without a re-circulation system, all the water sitting in the water line that has cooled down (from sitting in the water line) has to pass through the pipes and your faucet before the hot water from the water heater will reach your faucet. Many gallons of water are wasted while waiting for hot water to arrive.

A hot water re-circulation system uses a return line piped from your furthest faucet from the water heater directly back to the water heater. Instead of wasting hot water sitting and cooling in pipes, the water is circulated back to the water heater and reheated. As a result, you get hot water very quickly after turning on your faucet.

A large pump is not needed for residential re-circulation systems because the water only needs to move slowly from the water heater, through the water pipes, and then back to the water heater.

In this type of water re-circulation system, the pump is normally installed into the drain line of the water heater. The outlet of the pump would be mounted facing towards the water heater so the water flow of the return line would be pumped into the bottom of the water heater.

For this type of application, the Grundfos #UP15-29SU can be used and is a very quiet and efficient 1-1/2hp pump which uses 87 watts. For even more saving you can also incorporate a timer and/or thermostat. Grundfos offers a 24 hours (15 minute interval) programmable timer that is made to attach to this pump. Timer control #599388.

For optimum efficiency you set the timer to come on just half an hour before you wake up in the morning and again half an hour before any other peak time water use is needed during the day or night according to your schedule.

A thermostatic switch (thermostat) is also available for this Grundfos pump and allows the pump to be turned on and off according to the temperature of the water by a sensor attached by a clip-on mounting to the pipe. These thermostats are available in a low temperature rating or a high temperature rating and are available for 1/2" copper pipe or 3/4" copper pipe.

The low temperature rated model will turn the pump on when the temperature of the water reaches approximately 85°F and will turn the pump off when the temperature reach approximately 105°F.
1/2" Clip-On Mount - Low Temp Thermostat for 5/8" O.D. = #595443
  • 3/4" Clip-On Mount - Low Temp Thermostat for 7/8" O.D. = #595444


  • The high temperature rated model will turn the pump on when the temperature of the water reach approximately 105°F and will turn the pump off when the temperature reaches approximately 115°F.
  • 1/2" Clip-on Mount - High Temp Thermostat for 5/8" O.D. = #595656
  • 3/4" Clip-on Mount - High Temp Thermostat for 7/8" O.D. = 595657


  • An air vent may need to be installed in the return line at the highest point to help prevent an air lock should air get into the water line. An air lock will prevent the water from moving through the water line, even if the pump is running, and could cause damage to the pump. An air vent will automatically release air in the water line.

    OUR HOME
    PAGE
    ARTICLES
    INDEX
    PLUMBING
    FORUM
    PLUMBING
    MFRS
    PLUMBING
    CONTRACTORS
    PLUMBING
    HISTORY
    PLUMBING
    SUPPLY
    COPYRIGHT ©
    1995-2014