Hot Water Recirculation System

Hot Water Recirculation System
January 31, 2013 Lorelie
hot water recirculation system

Hot Water Recirculation System - What You Should Know

Every year, gallons upon gallons of water are wasted in the United States and in Europe simply because people are waiting for their water to get at the right temperature before they go take their shower or even wash their hands.  The total cost of all the wasted water will be in the thousands per year.  Not only is it a waste of money, but also a waste of resources.

Often times, this wastage of water is unavoidable as the water inside the pipes cools down which is why when you turn the hot water tap on, it is the cooled down water left in the pipe that leaves the faucet first.  In traditional storage tank water heating systems, hot water goes out of the water heating unit into the pipes before it exits the faucet.  When you close the faucet, there is hot water left inside the pipe which cools down in time.  This means the cooled water sitting in the pipes leaves the pipes first, and this is the initial cold water that you get when you open the hot water tap.

If you want to avoid having cold water left inside the pipe, then you should have a hot water recirculation system installed with your water heating system.  The hot water recirculation pump sends cool water left in the pipes back into the water heater via a return line.  The pump basically circulates water from the water heating unit to help keep it hot.  This happens in a continuous loop ensuring that hot water is readily available from the tap as soon as you open it.  The recirculation of warm water is slow-moving, but constantly circulates hot water, even from the farthest hot water pipes.  This helps to keep the water in the pipes hot so that no water is wasted when opening the hot water tap because hot water instantly surges from that point.

A hot water recirculation system involves a not so complex plumbing system to help move water in a loop.  This helps to provide how water in every fixtures instantly, without any need to wait a few seconds.

The most common type of hot water recirculation system uses a dedicated return line.  This will start from the point of use that is farthest from the storage tank back towards the storage tank.  If a home does not initially have a return line installed, they commonly use the cold water line and use it as a sort of return line through the use of a temperature control device that closes the connection between the hot water lines and the cold water lines at specific temperatures.   The downside to this when compared to a dedicated return line is that the cold pipe may become heated along with the water in it.

Listed below are the features of a hot water recirculation system:

  • The pump circulates water from the pipes to the water heater.
  • A thermostat helps to control the temperature in the return line.  This in turn engages the pump automatically when it senses the water is going below the desired temperature of 95° to 125° F.
  • A built in timer initiates the thermostat to help keep the temperature in check as specified intervals.  A programmable timer comes as optional.  This helps homeowners to program the time so that it can keep check of the temperature before their routine use.
  • A check valve is installed to prevent any back flow of water.  This helps to prevent the reversal of water flow that may potentially contaminate the plumbing system of the home.
  • An isolation valve allows homeowners to isolate the pump from the system in case they need to remove it for cleaning purposes.

 

Plumbing Types

Dedicated Loop – the recirculation pump for this type of system is installed on a pipe connected to the water heating unit.  This is mostly because this is the coolest side of the loop.  The common installation would be to have a hot water line passing every hot water fixture.  These fixtures are then connected to the hot water line via a valve.  With this setup, as soon as a valve is opened, hot water almost immediately rushes out of the valve.

Integrated Loop – this type of system is more like a retrofit, but it can also be installed on new construction.  The pump is basically installed under the plumbing fixture that is farthest from the water heating unit.  The pump is equipped with a sensor that engages the pump when the water temperature drops below 85° F and switches it off once the water temperature gets at 95° F.  Newer recirculation pumps can be adjusted from 77° F to 104° F.  With this type of system, the hot water is returned to the water heating unit via the cold water pipes.  Although this may raise the temperature of the cold water slightly, the cold water reverts back to its normal temperature in no time.

 

System Types

Demand-controlled System – this type of system operates on a pump that is activated by a switch or motion sensor.  This type of system costs very little to operate, but does not provide hot water as quickly as other setups.  The system basically has a switch or motion sensor near each hot water fixture and activates the energy-efficient circulation pump once it detects motion in water.  The pump on the other hand is equipped with a temperature sensor and check valve to prevent water from going to the return line.  A sensor is placed at the farthest tap so that when hot water gets there, the pump is automatically turned off.

Gravity-fed System – this type of system relies on thermosiphoning wherein hot water will rise at the top of the system while the much denser cold water will settle down at the bottom.  In order for this type of system to work, the water heating unit needs to be located at a much lower level than the hot water fixtures it will be providing hot water with.  Although this type of system seems somewhat more economical due to its gravity-fed name, it actually uses more energy than other systems as it is kept on non-stop.  The only advantage with this type of system is that it is user-friendly because there are no pumps to install.

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