A recirculating pump brings instant hot water to any room in the house There are two types of recirculating systems, closed systems and open ones.

A closed system is like that found in a hot water heating system, where radiant heat from the water is used to heat the home. The system is always full and water is neither added nor removed. As a result, the quality of this water deteriorates to the point where it is not safe for drinking.

An open system, on the other hand, allows both the inflow and outflow of water during the recirculating process.

This is the type of system we're discussing in this article. Unlike closed systems, where the water is subject to the infiltration of impurities, open systems must maintain water integrity.

Nearly everyone is familiar with the ritual of turning on their shower valve and letting the cold water run out before getting in the shower, or for that matter doing the same thing at the sink before washing his hands. This is not only an annoying waste of time, but a tremendous waste of water as well.

The solution to this problem is the recirculating pump, an item that's becoming more and more popular in new homes. Besides adding value to the home, it provides the comfort and convenience of instant hot water at every faucet and valve, without the prohibitive cost of installing instant water heaters in each location..

While fresh water becomes scarcer in the face of ever-increasing public demands for it, more water continues to be wasted.

The typical U.S. home wastes between 12,000 to 38,000 gallons of water each year waiting for hot water. (see more water facts)

This water places an unnecessary burden on municipal wastewater treatment systems and other infrastructures. This wasted water poured down the drain was heated and now when the water is shut off the hot water remaining in the pipes will just cool down again. Throwing HOT paid-for water down the drain not only aggravates shortages but also adds needless demands on our water producers and our Gas and Electric service providers.

In addition, all water heaters experience stand-by losses and operating stress; they cycle on and off several times during the day.

A recirulation pump reduces undo stress on the tank caused by the thermo shock of new cold water entering the system, by tempering this new water with the returning warm water.

Recirculation decreases the amount of cold water that enters the system, and that results in much less condensation and less thermal stress on the tank. Yet the actual circulator requires a minimal horsepower motor in the range of 1/12 or 1/16 hp, or just enough to keep the water moving.

A hot water recirculation system consists of a small pump mounted near the bottom of your water heater along with a swing check valve. One continuous trunk line connects all the faucets, showers and water appliances in the home. At the last faucet or water fixture, a return pipe is installed that returns to the pump. The return line can be installed either under the floor or in the ceiling.

When the system calls for the water to be heated, the circulator pump turns on and moves the water through the water heater, through each faucet, shower, water appliance, etc. and back through the return water pipe. This system becomes one continuous pipe loop with hot water available when you want it.

If you install a recirculation pump, be sure all hot water pipes are insulated and leave at least a 2-inch clearance between the hot and cold water lines. Branches off of the main hot water supply should be kept as short as possible. Local codes may require the installation of a hot water expansion tank for secondary pressure relief on cold water supply lines with check valves.

It is very important to be certain that there is no trapped air in the pipe; which can damage the pump.

With the Grundfos recirculating pump, air removal can be accomplished by removing the back plug from the pump when the system is charged with water and the pump is turned off.

The pump's slotted shaft is then rotated until the air no longer escapes. Then replace the back plug. When water is shut off and faucets are opened anywhere in the house, air can be introduced into the system. To prevent air from collecting in the return line, slope all the pipes so air will flow to the high point in the line and then put a valve there so you can release the air periodically. .

For even more savings you can also incorporate a timer and/or thermostat.

Most three-prong wall timers should work, but Grundfos makes an excellent timer for their most popular model (#UP15-18SU). It can be set in 15-minute increments and mounts right onto the pump. The timer only allows the pump to turn on at certain times. If you only need hot water in the morning, for example, you could set the timer for 6am to 8am. Then the pump would only recirculate the hot water during that time. The thermostat turns off the pump when the water in the pipes reaches a certain temperature. So once the water in the pipe is hot, the pump turns off.

When the timer and thermostatic controls are installed together, in series, the circulator operates ONLY at the preset clock times specified by the user AND ONLY when the temperature conditions of the thermostat are met. That is, if either the timer control or the thermostatic control switch is open (off), the circulator will not operate. The thermostatic control automatically turns the circulator off when the temperature exceeds approximately 120-125°F and back on when the temperature drops below approximately 90-100°F. The thermostat is not adjustable.

To install the pump, you'll need the pump & flanges/unions, a swing check valve, and pipe and fittings to run the return line back to the pump. The threads on the pumps are designed to attach only to flanges or unions since there are many different sizes and types of pipe. Using flanges/unions means the same pump will fit any sized pipe. An identical replacement Grundfos pump should fit existing fittings. The ISO (isolation) flanges have a screwdriver shut-off built into them so the pump can be removed from the system without turning off the water supply.

See Also:

Links to Related Websites:
Water Facts
Hot Water Recirculation - FAQs
Hot Water Recirculation News and Information


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