Hot Water Recirculation Pump

Overview

A hot water recirculation pump keeps heated water moving in a loop between the water heater and the fixtures so that hot water arrives almost instantly at the tap, rather than running cold water down the drain while the line warms up. It is a small, quiet circulator sized for low flow and modest head, run intermittently under control of a timer and a temperature sensor.

The recirculation-pump-motor is a wet-rotor design: its rotor spins in the pumped water and needs no shaft seal, with the stator isolated behind a thin can. It drives the recirculation-pump-hydraulic end, where the impeller builds the flow. The rotor rides on the recirculation-pump-bearings, lubricated by the water itself. A recirculation-pump-check-valve blocks reverse flow, the recirculation-pump-control decides when to run, the recirculation-pump-unions allow service without cutting pipe, and the recirculation-pump-wiring brings in power.

How it works

When the control calls for circulation, the wet-rotor motor spins the Impeller inside the recirculation-pump-volute. The impeller throws water outward, raising its pressure and pushing it around the recirculation loop so a fresh charge of hot water is always waiting near the fixtures. Because the rotor runs submerged, the recirculation-pump-can keeps the live stator dry while the ceramic recirculation-pump-bearing-sleeve and thrust washers take the load with only water for lubrication, which is why these pumps run nearly silently and last for years.

The recirculation-pump-control is built around an Microcontroller with SMD Passive (R/C/L) and a small LCD Panel showing the mode and setpoint. It runs the pump on a daily schedule and reads the recirculation-pump-temp-sensor strapped to the return line, energizing the motor through a Relay only when the loop water has cooled below the target. That avoids running the pump continuously, saving energy while still delivering near-instant hot water during the hours people actually use it.

The integral check valve stops the loop from thermosiphoning backward when the pump is off, and the union set lets a plumber drop the pump out for service without disturbing the surrounding pipe. O-rings seal the casing and unions, and the Wire Bundle and Connector land power at the motor terminal box.