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How to Get Hot Water with a Recirculating Pump

This Old House plumbing and heating expert Richard Trethewey explains how a recirculation line can save energy, money, and time

Are you tired of waiting minutes for hot water to come out of your faucet and wasting cold water in the process? This Old House plumbing and heating expert Richard Trethewey explains how to remedy this common problem found in large houses and commercial buildings with a recirculating pump.

A common question is: Is a hot water recirculating pump worth it? For Trethewey, the answer is yes. In this video, he explains how a recirculation line can save energy, money, and time.

Accessing Hot Water With a Recirculation Pump

  1. A recirculation line is a separate water pipe that runs off the hot-water line from the farthest plumbing fixture back to the water heater.
  2. A pump at the water heater moves hot water through the recirculation line. Any cold water in the recirculation line is returned to the heater.
  3. A check valve must be installed in the line to ensure hot water only goes in one direction.
  4. An aqua-stat is mounted to the hot-water pipe. When it senses that hot water is returning to the heater, it shuts off the pump.
  5. A timer is used to ensure that the system isn't maintaining the recirculation line when you're away at work or sleeping.
  6. Pumps and fittings can be used to push cold water in the hot-water pipe into the cold-water line until it senses that hot water has finally arrived from the heater.