Installing an Instant Hot Water Recirculating System

A hot water heating system
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A hot water recirculating pump can be used to provide instant hot water to showers and faucets when it is needed most, without wasting water down a drain as you wait for hot water to arrive from the water heater. There are several different designs for such systems, but the instant hot water recirculating system we'll show you here is fairly easy to install in an existing system. 

Unlike some other systems, this system requires no dedicated hot water loop, and it works through means of a circulating pump installed at the water heater and a check valve installed at the sink farthest away from the water heater.

The check valve allows the pump to divert and circulate water back to the water heater until it is warm enough, then shuts off when the water in the hot water pipes is warm enough for use. The result is that the water in the hot water pipes is always warm when you need it, and you never have to waste water down the drain. 

Aside from the hot water recirculating kit, which includes both the pump and the check valve, all you'll need is a pair of flexible supply tubes and a few simple tools. You can complete this project in just a few hours. 

Here are the steps:

  1. Begin by shutting off the water on the shut-off valves on the cold water pipe running into the hot water heater. This valve is usually on top of the heater. Check to make sure that flow of hot water is completely stopped opening a faucet somewhere in the house and seeing if any hot water flows. If the shut-off valve hasn't completely stopped the flow, you may need to shut off the main water supply to the house. 
  1. Disconnect the flexible water supply line on the hot side of the water heater where it goes into the water heater. Have a rag nearby to catch any residual water that will come out when the flexible pipe is disconnected.

    NOTE: You may find that these pipe connections are not flex lines, but instead are fully plumbed rigid pipes. If so, the process of splicing in the recirculating pump will be a little more complicated, but still possible. 
  1. Set up the pump by programming the times that you want the pump to run. The timer allows you to set operation, so the pump runs when hot water is most needed.  It’s a good idea to set the timer on the pump now because will be a little more difficult to access after it is installed.  
  2. Screw the pump onto the hot side of the water heater. As you tighten it, make sure the timer face is turned in a direction where it can be readily adjusted. Plumber's tape can be used on the threads of the water heater nipple, but it is usually not necessary if there is a rubber gasket inside the female nut of the pump fitting.
  3. Reconnect the hot water line to the top of the recirculating pump, and tighten with channel-type pliers. You can loop the flexible line if necessary, but make sure there are no kinks that might restrict the water flow. 
  4. Now go to the sink that is farthest away from the water heater to install the check valve. Shut off the water to the faucets by closing both supply valves controlling the hot and cold water supply tubes. 
  5. Disconnect the faucet supply tubes from the shut-off valves under the sink. Have a towel and a container ready to catch the water that may drain out when the tubes are disconnected. Now you will connect the check valve to the faucet supply tubes. 
  1. Screw the existing supply tubes coming down from the faucet tailpieces onto the top two outlets on the check valve, with the hot water line positioned on the left and the cold water line on the right.
  2. Now run the new water supply tubes from the check valve to the hot- and cold-water shut-off valves.  Make sure they are connected to the correct valves. Normally, the hot water pipe will be the one on the left, and the cold water pipe will be on the right as they come out of the wall or up through the floor. If this isn’t the case, you will need to make adjustments.
  3. With the new supply tubes tightly connected, you can mount the check valve to the wall, using the screws provided in the kit. 
  4. Turn the water back on to both the sink faucet and the water heater. Run water at the far sink until all of the air is out of the lines. Check to make sure that there are no leaks at any of the connections before plugging in the power supply to the recirculating pump.

    Note: If you ever have to shut the water off to the house, make sure and unplug the pump to avoid burning it out. The pump needs to have water circulating through it whenever it is running.