Using recirculation to fix the slow hot water delivery

Does it take too long for hot water delivery and have a pleasant, fast shower or uninterrupted use at the kitchen, for dish cleaning? One of the solutions for this problem is to install a recirculating pump, a pump that can be easily mounted on a dedicated return cold line. The recirculation is useful in both new house developments and as an add-on in retrofit situations, resulting in sufficient and fast hot water supply.


The recirculating pump saves the time, energy and water, by delivering hot water almost instantaneously, from the water heater (either electric or gas powered) to one or more fixtures. 

Keep in mind that none of the conventional tank-type or on-demand water heaters deliver hot water instantaneously; when the recirculating pump is installed hot water is delivered much faster than without the pump. This pump can be, depending on the manufacturer and model type, factory built inside the unit (some tankless models) or externally added. One of these tankless models is Rinnai and its Circ-Logic features that works with the dedicated return line or cross over return that uses the thermal by-pass valve. It allows the user to customize the system based on; piping insulation, length of the loop...

Installation tips

The recirculation is recommended mainly for commercial applications and large homes while it is not worth the effort and money for smaller houses.

The recirculating pump is usually installed on the cold water line either close to the water heater, at the point of use or at the furthest point from the unit, so more fixtures can take advantage of the fast hot water delivery.

So, the change on the existing plumbing system includes the dedicated return line from the desired fixture and back to the water heater, covering that fixture with the hot water and any fixtures in between.

Choosing the system

Once decision was made that recirculation is needed, next thing is to pick the system;

  • The system that circulates hot water all the time... continuous work
  • The system that works on demand, and
  • The system where hot water delivery is based on the timer or temperature

While comparing the systems... the continuously working system is the last recommended due to its constant work and energy waste when hot water is not in use. It is OK to use it if the system utilizes a smaller pump, as it draws little electricity. Better system is the one whose work is temperature- or timer-based where hot water delivery is faster, but water at the beginning is warm, not hot.

According to some reviews, the demand type recirculating system is the best as it utilize the strong pump for fast delivery, activated by a switch and when used with the timers, more energy is conserved, as it operates only when demand is high, for example.

One can also go with the indirect water heaters that are equipped with the recirculation port, used for the return line. If the unit is not equipped with such a port, it is recommended to use a T-fitting installed into the drain line.

Either type of the recirculating system is used, the benefits are there; water at the point of use fixture is hot and delivered fast and what is also important hot water stays in the loop eliminating the water waste, energy loss and inconvenient showers. In addition to the return line installation, it is a good practice to insulate all the hot water lines therefore reducing the energy loss greatly.

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