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New Water Heaters ... How To Use Energy Factor To Choose or CompareJust in case you're not sure whether to get a new storage heater or a more efficient tankless water heater let's cover the way to compare costs of heating water using gas, propane or electric since whether you get a tankless or storage unit the choice is made even more complicated by the available models that use different fuels. Beware smooth talking salesmen ... their job is to sell their products not look after your best interests. Take a bit of trouble on this page and you will place yourself in a position to really ask vital sensible objective questions that will almost certainly guarantee you a better deal from any salesman. The basic costs of each form of energy ... Cost of Electricity, Oil Gas and Propane Energy Units Used On This WebsiteThe table below is an estimate of prices going into 2006 based upon the rapid escalation in energy prices from April 2005 onwards. You will see 2 columns ... the first is the way energy of the particular fuel is normally quoted and sold and the second column is the same information normalised (ie on the same basis to make comparison more easy). It is blatantly obvious looking at this table that electric power costs dramatically more than other types of fuel and the basic reason is that electricity has to be made from one or other of the alternative fuels. However this comparison also does not tell the full story since it ignores efficiency of fuel use ... electric power use is more efficient for example. In general you can see that Propane also called liquefied petroleum gas is about 50% more expensive than natural gas and this means where you have a choice between these 2 gases then propane is the one to avoid all else being equal.
The Importance Of The Energy FactorYou'll remember the definition of energy factor is a the measure of the overall efficiency of a water heater (any kind) based on the an individual model performance characteristics. The parameters against which it is measured are set by the U.S. Department of Energy test procedures. The testing includes the models recovery efficiency (ie heat recovered by preheating colder streams for example) standby losses which are those lost to the atmosphere normally through insulated walls on a storage tank and expressed as a fnction of the energy input. Energy factor can easily be used in conjunction with your local fuel costs to estimate the annual cost of operation of any water heater. Think of this factor as a direct efficiency comparison measure ... in other words an energy factor of 75 is 50% better than an energy factor of only 50. The implication is that it can be used to compare 2 different mode's energy consumption. It cannot be used to calculate the energy used by any single individual unit. Comparison Energy Factors ... Best To Worst On Average For All Types Of Water HeatersThe table below was calculated by me in 2004 from individual data on a wide range of different heaters data published by GAMA
BEWARE ...To clarify the point about energy factor being useful for comparison purposes you'll notice that on average electrical Tankless Hot Water Heaters (light blue row) use about 50% less energy than oil storage heaters (pink row) ... ie (0.9 - 0.59 divided by 0.59) Remember this is comparing energy usage not energy cost so be careful. To compare cost we must also take price to the different fuels into consideration as below ... Example ... an average oil storage heater (energy factor 0.59) uses 1 million Btu to heat a specific quantity of water at a cost of $16.48 per million Btu (see above table). The average ELECTRIC tankless water heater will use only 1 million x 0.59/0.99 = 596,000 Btu at a cost of $34.52 per million Btu = $20.57. So you can see despite the electric heater using very much less energy to heat the same amount of water it still costs more ($20.57 compared to $16.48) because electric power is so much more expensive than oil power or energy. |
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