Saving dollars - and energy - on your electric water heater
Friday, May 6, 2011
With time-of-use billing, it's more important than ever to program your electrical water heater and other appliances properly
by RALPH WINFIELD
Electric water heaters are used on many farms and rural properties in Ontario. The only significantly cheaper source of energy for water heating is natural gas, which is not available to most rural properties.
So let's look at how the standard 40- or 60-gallon electrical water heaters perform their functions. An understanding is critical so that adjustment errors are not made.
All typical tank units have two water heating elements. One is in the top third of the tank, the other near the bottom. Most 40-gallon tanks will have 3,000-watt heating units. Sixty-gallon tanks will likely have 4,500-watt heating units. Some variations may occur. We have a newer Energy Efficient 40-gallon unit with 3,800-watt elements top and bottom.
Only one element will be energized at a time because of the method of wiring. Each element has a separate thermostat so the water temperature can be set independently.
But now for the critical piece of information. The top element always has electrical priority. The top, smaller part of water volume will be heated first – to the set point temperature. When that water temperature is reached, electrical energy will be available to the lower element so that it can heat the larger portion of water to the set temperature of the lower element thermostat.
My point here is that if you need relatively large quantities of hot water during short periods of time, the lower element thermostat must be set at the desired water temperature.
The mistake made by many is to lower the temperature setting of the bottom element to save energy. This will make the upper element come on more often to top up the water temperature. This will cause some people to turn up the top thermostat to provide hot water on demand. This is a recipe for disaster. The small quantity of very hot water at the top will be too hot for bathing or showering.
If the electrical water heater is well insulated – and most newer units are – it will have immersion elements in place of the old strap-on elements, which were not as efficient.
Time of Use (TOU). In preparation for the switch over to varying rates for electrical energy during a 24-hour period, I put a kilowatt-hour meter on our well-insulated, 40-gallon water heater, which has 3,800-watt immersion elements.
For the period of July 14 to Oct. 20, 2010, the daily water heater consumption averaged 8.5 kWh/day. If we add the 9.2 per cent line loss factor that Hydro One imposes, that brings us up to 9.28 kWh/day. Please keep in mind that we are a family of two with a daughter, son-in-law and granddaughter living with us a few days each week during the market gardening season. When we had two teenage daughters living here full time, I am guesstimating that the water heating energy consumption would have been close to double that amount!
We have been getting actual meter readings each month for the last six months from Hydro One. The figures range from a low of 40 per day to a high of 80 in the colder and darker months. The more we can put into the "Off-peak" hours at 5.1 cents/kWh versus "Mid-peak at 8.1 or "On-peak" at 9.9 cents/kWh, the more dollars that can and will be saved on the monthly bill.
What can I do to move consumption for water heating off-peak? My present plan is to put a time clock on the water heater so that it can only heat water between 9 p.m. and 7 a.m. My wife has already made plans to accommodate this water heating period.
The new dishwasher has a four-hour start delay option. That means that she can set the dishwasher at 7 p.m. and it will not start until 11 p.m. Similarly, she is prepared to run the clothes washer after 9 p.m.
If we run out of hot water too frequently I will put in a second water heater, plumbed in parallel with the existing unit and also controlled by a time clock. The savings in energy costs will pay for the second water heater in about three years, a good return on investment.
Other energy savers. Most of us on farms need to consider certain lighting fixtures that can be upgraded. I am amazed as I tour the country side and see all the old-style 175-watt fluorescent yard lights that are still in place. These can be replaced with 60-watt sodium units. A two-thirds saving in energy all night every night will soon pay for the new fixture.
About 40 years ago, I installed a 4x40-watt fluorescent light fixture in the family room of our old farm house for my in-laws. We replaced it with a new fixture that utilizes 4x13-watt high efficiency bulbs. The power consumption is reduced to one third of the original amount. There is no problem in reading the paper and my wife is much happier with it. A similar but smaller-two tube-fixture in the entranceway will also be replaced.
In short, with a little forethought, many electrical usages can be reduced and others can be shifted to off-peak times, saving energy and money. Any action that will provide payback in less than three years is a must do! BF
Agricultural engineer Ralph Winfield farms at Belmont in Elgin County.