Water, water, down the drain

Turn on the shower and wait, wait, wait while fresh cold water goes down the drain until the hot water finally arrives.  Another waste of an increasingly precious resource.

It is often said that fresh water will be the oil of the 21st century, increasingly sought after by competing claimants, harder to obtain, and expensive. That annoying waste while waiting for hot water may account for as much as 10% of your home’s indoor water use.

Ever wonder how big hotels provide instant hot water? It turns out that most hotels continuously circulate hot water through a piping loop which connects to all of the plumbing fixtures and then returns to the water heater, so hot water is always close at hand.  A few years ago, as houses got larger, and as our wealth enabled us to layout houses for comfort more than efficiency, homes started to be equipped with these systems also. Unfortunately, though they save water, they waste quite a bit of energy.  First there’s the electric pump used to push the water around, then there is the constant heat loss as hot water flows through cooler spaces, so that the water heater has to cycle on more often. Piping insulation is mandatory on these systems, of course, but the bottom line is still a system that wastes energy or wastes water.

Another solution, increasingly in use for the last few years, is ‘demand’, also known as tankless or instant water heaters.  Instead of the conventional tank that heats fifty gallons of water at a time and stores it for later use, these heaters only operate when a fixture tap is opened and the water starts to flow.  They just heat the water being used immediately, doing so very quickly and reasonably efficiently. Ideally, they are installed close to the fixtures, so there is very little water waste, and they sometimes only serve a few fixtures.  A typical house might have two or three of them, especially if the bathrooms are far flung. Both gas and electric versions are available. The down side of these units is their cost – both for the heaters themselves and for the large gas or electric services they need, and also for the high temperature flues the gas versions need. For a thorough discussion of the subject see the online consumer information.

But what can the vast majority of us do, who have conventional water heaters and an existing piping system, fully concealed within the walls and ceilings of our homes? Some ingenious person figured out a very simple, efficient approach that is both water and energy efficient.  This system, called an open loop, connects the existing cold and hot water supply lines at the most remote fixture from the water heater to create an artificial loop system.  The only new components are a small electric pump, a pushbutton, a thermostatic sensor, and an electric valve.

Here’s how it works: A few seconds before you need hot water (maybe you have entered the bathroom to shower and are about to disrobe) you push a button by the sink. The button activates the pump, which is generally hidden in the base cabinet under the sink, and which is connected to the hot and cold water lines which serve the sink. Water from the hot water pipe is pumped into the cold water line, where it returns to the hot water tank, reversing the usual flow direction. When hot water arrives, the thermostat shuts off the pump.  Now you have hot water at the sink, without having spilled a drop and having used the pump for just a minute.  In most bathrooms the branch pipe which serves the shower is only a few feet from the main pipe that now has hot water, so the shower will get hot almost immediately.

Depending on the layout of your house, one pump station at the fixture furthest from the water heater may be sufficient, or you might need two or more if the piping system runs off in all directions. In any case, very little water is wasted and the pump is only running a few minutes per day.

A couple of manufactures make pump and control systems designed for this purpose. The product line which looks the most interesting to me is the ACT,Inc. Metlund “D’MAND” .  All of the components of the system are included and it looks easy to install. There are three pump sizes available and three control system choices: a push button, a motion sensor (the pump would start anytime motion was sensed – possibly not the best idea) and for those who are technology addicts, a remote control. The most difficult part of most installations, one imagines, is getting a power source to the location where you want to locate the pump. List price of the basic unit is $339.50. We plan to order one of these and will let you know how our installation goes.

Another manufacturer to look into is Chilipepper . Their unit has a bigger pump than the D'MAND systems, which presumably translates into quicker hot water, but also reportedly makes for a much noiser unit.  It is also cheaper, at $179.99, but to me silence is golden.  Laing Inc.also makes good circulation pumps but they don't seem to have a unified system.

Please let us know if you have any experiences with these systems - we would love to share the information.

Comments

[draining machines]

When hot water arrives, the thermostat shuts off the pump. Now you have hot water at the sink, without having spilled a drop and having used the pump for just a minute. In most bathrooms the branch pipe which serves the shower is only a few feet from the main pipe that now has hot water, so the shower will get hot almost immediately.

-mike-

[solar hot water systems]

The solar energy water heaters help to find the most effectual solutions for residential and commercial water heating.

[solar hot water system]

Nice post, thank you for sharing. It is no doubt that the solar power has been developed for several years, and it is increasingly being used in daily life such as solar hot water system, solar car and so on. In the future, it will be essential for us decreasing the cost and developing it in more industries, as it is the green energy for the planet.

[Richelle Loughney]

Instant water heaters are a great idea. Though water tanks are more widely-used due to their cost-effectiveness, people will eventually prefer to have instant water heaters installed since they're more convenient.