What is an Electric Water Heater? Is it Better Than Gas or Oil?

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Energy in electrical form is most expensive because the primary energy source (eg gas or oil) has had to be processed into an alternative energy type ... electricity. However the big positive spin-off is the ease of installation, the wonderful convenience and range of appliance and heaters that can use this form of energy. Safety considerations are also much less than for gas fired or oil fired heaters whether storage or tankless heater types. There is another very important factor in deciding to use electricity to heat water. Consider the following ...

When oil or gas is used in a water heater a lot of energy is wasted because fuel is burned and the hot gases all got to atmosphere as wasted energy. When an electric heater is used there is no wasted gas. When you buy any heater you will notice that there is a something called the "Energy Factor" quoted ... in simple terms this is an efficiency factor. Electric heaters have 99% energy factors in most cases whereas gas or propane (LPG) heaters have much lower energy factors between 46% (for the worst) to 64% for the best with an average of around 56% for all the different makes (reference GAMA). This means that you can afford to pay about twice as much for an electric unit of energy as compared to the same energy unit for a gas type water heater. Electric heaters are generally a very good choice for this reason especially as natural gas prices rise because in these cases energy efficiency is even more important (the cost of all the wasted flue gases just goes up and up) than when energy prices in general are low. The question now remains ... do you buy a storage or tankless electric water heater? To answer this question you need to check models from reputable suppliers but first consider the information below .... In general electric tankless water heaters will win on an all-in cost comparison is made.

Heating water uses considerable energy and some is wasted in hot water storage tank heaters. Tankless water heaters use less energy than  storage water heaters for the same amount of hot water supplied. Here's why ...

In a hot water storage tank heater, energy is required to heat the water in the storage tank and to keep it hot so that it is available when you need it for a bath or shower. In both types ie storage hot water heaters and tankless heaters, the basic efficiencies of initially heating the water are very similar. This is because the amount of energy required to heat a fixed amount of water is determined by a simple formula as follows ...

Flow rate of water in any units (eg gallons per minute) x specific heat x the number of degrees the water must be heated by. In simpler language this formula means if you double the flow and want to keep the temperature the same you must double the energy supplied. It does not matter where the energy comes from ie electricity or gas or any other energy type

However here is where the difference in overall energy efficiency lies .... a feature of tankless water heaters is that no energy is consumed in overcoming heat losses commonly encountered in a storage water heater tank even though the storage heater may be well insulated   ... insulation does not prevent the heat loss completely but reduces the rate of heat loss. One and a half inches of foam-type insulation is about right for most heaters.

Important questions for the energy conscious consumer are "How much energy is lost during standby?" and, of course the really important question "How much are the hot water storage tank energy standby losses going to cost me?" The ability to compare cost and energy savings between the alternative tankless and hot water storage tank systems or features is important.

Here is a brief summary and comparison of the features between the tankless hot water system and the storage hot water system. Each point is covered in some detail on my main website ....

Hot Water System feature variables Tankless hot water system features Storage tank hot water system features
Energy cost Lower cost ... reduced energy losses Higher losses ... higher energy usage
Unit size Much smaller than hot water storage tank Large compared to tankless hot water heater
Installation cost Small compared to storage tank heater in new structures but higher in retrofit More complex to install in new structures
Installation space Compact unit .. saves space taken up by storage tank hot water heater which can be used as closet for example Bulky heater and tank system with difficult access normally
Capacity When large quantities are required simultaneously flow can reduce or temperature of water is reduced Normally depending on size of tank capacity is higher for simultaneous use

Life Expectancy of tankless water heaters ... Most tankless models have a life expectancy of more than 20 years. Storage tank water heaters last 10 to 15 years. Most tankless models have easily replaceable parts that can extend their life by many years more.