Tankless Electric Water Heaters: Will They Save You Money?
I was thinking about what topic to post this weekend and got a call from my sister. She asked; Where can I get a tankless water heater? This was serendipitous, because I had just read an article on gas tankless water heaters and the comparative costs of installing one versus a standard gas water heater. In that article the comparison was not very favorable. Because you want to know? Well, it looks like you are renovating your utility room and wanted to reclaim the corner space your standard water heater used to be. So I did a quick research.
My sister doesn’t have gas service, so I researched the tankless electric heaters available. Now a couple of things to think about very carefully when it comes to tankless water heaters, especially electric ones, is your family’s lifestyle. If you have 4 teens and 2 working adults, you may pay more to heat your water with a tankless heater than if you have a standard water heater.
This is especially true if you live in colder climates or if your water comes from a deep well. In these cases, the incoming water will be colder than if you live in, for example, Florida or Texas, so you will need to increase the water temperature more than if you lived in Florida (the average temperature of the water from the tap is approximately 70 degrees in winter, in colder climates the water is 40 degrees from the tap). Since teens take longer showers, the savings may just not be there.
General physics will tell you that it takes 1000 watts to raise 4.1 gallons of water to 100 degrees. Based on this, if you are importing 40 degree water, then 10,000 watts will be needed to raise 40 gallons (typical size for a standard water heater) of water to a standard 140 degree storage temperature. Now once it rises it will start to cool, albeit slowly with the improved insulation of newer water heaters.
At a KWh price of 10 cents, the cost of heating the water was $ 1.00. Now compare that to a tankless electric unit that produces a 65 degree rise in temperature at 2 gallons per minute (suitable in Florida with 65 degree inlet temp, not suitable in New York or Maine). This particular unit has a power of 14KW. That means that while it heats up, it will burn 14,000 watts of electricity per hour. Those same 40 gallons will take 26 minutes to heat up and cost around 60 cents to heat up. Sounds like a great savings, right?
Well not exactly. You see, when your standard tank is full, it reduces the energy required to heat the incoming water, as the incoming water will absorb some of the heat from the already hot water, reducing the input a bit to raise the temperature of the water. In a tankless tank there is no hot water stored, so the electricity needed to heat the water is expended in a direct proportion. When testing, the range of savings comparing tankless water heaters to standard ones has fallen into the range of 10 to 40 percent (the highest ranges are found in gas appliances).
So the next consideration is the cost of installation. In this regard, you will spend about $ 1,200.00 on labor and device to install a tankless electric heater, provided you have enough capacity in your electrical panel. Assuming so, we compare this cost to an approximate installation cost of $ 600.00 for a standard electric water heater. Furthermore, the expected savings are therefore according to government research:
For homes that use 41 gallons or less of hot water per day, on-demand water heaters can be 24% to 34% more energy efficient than conventional storage tank water heaters. They can be between 8% and 14% more energy efficient for homes that use a lot of hot water; about 86 gallons per day. You can achieve even greater energy savings of 27% and 50% by installing an on-demand water heater at each hot water outlet.
Source: http: //www.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12820
So let’s take a look at this. If you have 4 teens in the house, you probably use more like 120 gallons of hot water per day, so your savings will disappear unless you can afford to install 3 units (they cost about $ 3,600.00) to cover the two bathrooms, kitchen, and clothes. Washed. Even then, your savings will be between 27% and 50% of your water heating cost.
Government figures now say that the average electric bill allocates about 13 percent for heating water, so if your monthly bill is approximately $ 100.00, your savings could be 3-6.00 per month. Also, taking a shower and washing dishes or clothes at the same time will likely expand the capabilities of the tankless electric heater I’m using in the example, so you will need a larger one or another and a larger electric service unit. Your installation cost will increase dramatically. So the savings simply do not exist.
If, on the other hand, it’s only 2 and your lifestyle easily adjusts to accommodate the demand between showers, dishwashing, and laundry, then you could achieve some savings by installing the tankless heater. At this point, given the numbers, I couldn’t see any justification in my family. There is another factor to consider, tankless heaters have a useful life of 14 to 18 years; A standard water heater will last 6 to 12 years, depending on the hardness of the water and how well it is maintained. more to install will save them a minimal amount in operating costs, but it would save you the 7 square feet of space that the current water heater occupies in the utility room. In the end, you will have to decide if it is worth it.
