Legend has it that civilization began with hot water. Most of us could not imagine a life without that hot wake-up stuff in the morning. My grandfather heated hot water in a big pot on the wood stove for the weekly bath on Saturday evening. Lots of folks used to do that.

Today we have technologically advanced water heaters, so knowing something about the highly complicated maze of water heater choices may help you when the time comes to replace your water heater. Unfortunately we are so wedded to hot water that we typically make quick decisions based on short term economy and not knowledge, because we want our hot water now!

Today we have hot water heating devices that are essentially automatic. And like most of the mechanical things in our lives we don't know how they work or, God forbid, how to repair or replace them. We spend a lot of money heating water in our houses, and most of us would say it is worth it. After space heating and cooling, water heating is the next big consumer of energy in our homes. It does pay to keep informed about this issue if you watch your pennies. Since the cost of energy has risen and the politics of where energy comes from is constantly in the headlines, the pressure is on to improve and innovate and save energy dollars. At the same time the choices for consumers have multiplied and make it more confusing. In general the more energy efficient a water heater is, the more expensive it is in terms of up front costs. I recommend that you buy the most energy efficient heater you can afford if you plan to stay in your home.

In Israel, almost every home uses the sun to heat their water. The U.S. with lots of energy sources lags way behind using this free heat source. The U.S. would save billions in energy costs if everyone had a solar water heater on their roof. If you are concerned with green energy usage, this is almost a no brainer. I suspect that in time most homes in the U.S. will have these solar hot water heaters which do not pollute. I will save a deeper discussion of green solar energy systems for a future column.

Most folks have a big white tank water heater in their utility room. These are either powered by electricity, natural gas, propane gas or now, much less commonly, by fuel oil. If your home is heated by hot water then you have a “boiler” that may also be providing your hot water. The big white tanks, whatever their fuel type, have a metal tank inside surrounded by insulation. In older models there was lots of heat loss -- wasted energy as the tank sits full of hot water, and you are away or not using it. As the cost of energy has risen, American corporations that manufacture our hot water heaters began to add lots more insulation. Every year our white tanks have grown “fatter’ as more insulation has been added. Do-it-yourself home owners have also been encouraged to wrap their tanks with a second layer of insulation blanket.

Of the fuels that power our hot water heaters, electricity is the most expensive, but initially these electric hot water heaters are the cheapest to install since they do not require any sort of chimney. Natural gas is the least expensive fuel, followed by propane gas and then fuel oil, all of which have combustion taking place inside the heater and thus require a chimney. The most modern and efficient of these no longer require a vertical chimney and can be vented horizontally with the aid of a small fan through a plastic pipe that penetrates the side wall of the home. These souped-up tank heaters also pull their combustion air from the outside instead of using air from the inside of the house which saves energy dollars. A highly evolved electric water heater on the market, which the manufacturer says is extremely efficient, has a miniature heat pump built on the top of the white tank.

There is another new hot water heater on the market these days: the tankless heater. These have been used for years in Europe and Asia where energy costs have always been higher than the U.S. Instead of having a tank full of hot water waiting for you to use it, even while you might be away on vacation, tankless or “on demand water heaters” heat the water as it is called for. They are more efficient than tank heaters, they typically last longer, but they cost more to buy, and they can be more expensive to install. One of the things people love about them is that they never run out of hot water. If you have teenagers who take their showers before you, this might be a reason to buy a tankless heater. All gas fired hot water heaters used to have pilot lights that burned perpetually to light the gas when ever it was called for. These are now being replaced by automatic sparking devices. This alone saves serious money over the years.

The average life of a big white heater tank is 10-15 years. Some go at 9 years and some last for 20 years. If you are handy you should open the drain at the bottom of your water heater periodically and let out the cruddy mineral water that settles there and may corrode the tank and lessen its overall efficiency. There are helpful descriptions of why and how to do this on the internet. There is also an anode rod in your tank that has a sacrificial part to play. Instead of the water in your tank slowly corroding away the tank metal, the anode rod is eaten away instead. This too takes a simple replacement.

Lastly, if your hot water heater is providing water that is too hot to the touch at the tap, you may be wasting fuel when you mix it with cold water. One can adjust the temperature setting on your hot water heater, and it doesn’t doesn’t take an engineer’s know how to do that. Go to your hot water heater with a flashlight and a screw driver and perhaps a knee pad. Of course there is another way to look at water that is too hot. If you perpetually run out of hot water, before replacing the unit, raise the temperature setting, so that by diluting it you can stretch the total volume of hot water. Any way you look at it, having hot water at hand is a simple but significant pleasure of civilized life that one often takes for granted until it isn’t there.