| We all do it. Run water down the drain while | | | | |
| waiting for hot water. Who is going to jump | | | | There is another class of hot water |
| into the shower when the water is freezing | | | | circulating systems that do not require a |
| cold! Well no one. Is there a way to avoid | | | | return line. These systems use the cold water |
| running all of that water down the drain? | | | | line as the return line. The cold water line |
| | | | always connects to the inlet of the water |
| Yes. A hot water circulating system will | | | | heater, so it will always work. There are a |
| eliminate the need to run that water down the | | | | number of approaches being used for these |
| drain. There are several types of hot water | | | | cold water return type hot water circulating |
| circulating systems available, and they are | | | | systems. |
| fairly easy to understand. | | | | |
| | | | In some instances, for instance, where the |
| The first type of system is the full-time | | | | water heater is lower than the rest of the |
| circulating system. In this type of system | | | | system like in homes with a basement, a |
| the hot water outlet of the water heater | | | | gravity type system can be used. Since hot |
| connects to a pipe that runs past each | | | | water is less dense than cold water, the hot |
| fixture in the home, and then back to the | | | | water rises up from the water heater to the |
| water heater. A small pump circulates the | | | | fixtures and the cooled off hot water goes |
| hot water through the pipe, thus there is | | | | down the cold water return line back to the |
| always hot water near every fixture. Instant | | | | heater. A connection is required between the |
| hot water! | | | | hot and cold water lines, and a valve that |
| | | | responds to temperatures is installed between |
| But there is a price to pay! This is an | | | | them. Without a valve, the hot and cold |
| expensive system to operate, since the pump | | | | water would always mix when you used either |
| consumes some energy and is running | | | | one. |
| constantly; you have to pay for that energy. | | | | |
| But far greater is the expense of heating the | | | | Some systems use a pump connected between the |
| water. Heating water is very expensive, and | | | | hot and cold water lines with a built in |
| so when you pump it through a long pipe, and | | | | valve, and as with the full time systems, |
| the pipe is losing heat energy to the | | | | some are operated via a timer, some are |
| atmosphere around it, you end up spending a | | | | temperature controlled, and some use both |
| lot of money to heat the hot water piping and | | | | methods. |
| its immediate surroundings. | | | | |
| | | | Another type of system is known as a "hot |
| You can place the pump on a timer, so that | | | | water demand system". With the demand type |
| during periods that people don't normally use | | | | system, the user must push a button or |
| hot water, the pump is turned off. That | | | | utilize some other signal to start the pump, |
| helps, but it is still very expensive. Some | | | | and then when hot water reaches the fixture, |
| systems also control the pump by monitoring | | | | the pump shuts off. |
| the temperature of the water. The pump turns | | | | |
| off when it reaches a set point, and then | | | | The demand system is the lowest cost in terms |
| back on when the water drops to the lower set | | | | of operating costs since it does not cause |
| point. This reduces the energy consumption | | | | any more heat loss than if you just used the |
| by the pump, but does little to reduce the | | | | hot water fixture without the system. It |
| far larger energy losses of the heat loss | | | | only pumps when you "demand" hot water. |
| from the system. | | | | Typically such systems use only $1 to $2 per |
| | | | year in electricity for running the pump. |
| Another problem with these systems is that | | | | |
| they require a dedicated return line from the | | | | You obtain your hot water more quickly than |
| furthest fixture back to the water heater to | | | | if you ran the faucet full blast, and you |
| function. This is an expensive option when | | | | don't wastefully run water down the drain. |
| building a home, and a far more expensive | | | | You're happy and the environment is happy! |
| option to add on to an existing home. | | | | |