Residential electric hot water tanks are a solid reliable product that has been around a long time. But in an age where everything is high tech - or "green" - they don't draw a lot of attention. The technology is far from stagnant, however. Manufacturers have improved efficiency, DHW capacity and recovery time in recent years. Lower electricity rates in Manitoba and Quebec have long driven the market in those provinces. Today other factors are giving electric a boost. The ability of a storage tank water heater to maintain hot water for a long period of time with minimal energy use is more critical today as electrical utilities move to time-of-use billing. If families can do the bulk of their showering, dish washing, laundry, etc. in off-peak hours, the savings can be significant.
"It's all about how much you are going to pay for energy and when are you going to use hot water," remarked Claude Lesage, president of Giant Factories in Montreal.
As well, changing regulations have made gas water heaters more expensive. "The traditional electric storage water heater became more attractive because there weren't venting issues with it, it was simpler to install and it was a lower capital cost product," remarked Dave McPherson, general manager for Rheem Canada Ltd., Brampton, Ont.
"There is so much regulation, the cost of installing a gas water heater is getting higher and higher," added Paul McDonald, director, sales and marketing for Bradford-White Canada, Mississauga, Ont.
As well in Ontario, where 90 percent of the water heaters are rented, the rental companies are no longer tied to the gas utilities and will install an electric unit where it makes sense.
Water heaters are rated by energy factor (EF), which is an overall rating of the unit's efficiency. A typical 40 or 60-imperial gallon electric water heater would have a rating of .92 or higher. The higher the number, the more efficient it is.
Giant EcoPeak tanks gain efficiency with three elements
Natural Resources Canada (NRCan) rates water heaters by standby loss. In 2004 it reduced the maximum allowable standby loss (in watts) to 40+(0.20V) for tanks 11 to 59 Imp. gallons (50-270 litres) and (0.472 x V) - 48.5 for 60-100 gallon tanks (270-454 litres), where "V" is volume.
In 2009 B.C. introduced its own efficiency regulations, reducing the allowable standby loss to 25 watts for the smaller tanks and creating a headache for manufacturers by forcing them to make special products for B.C.
Explaining water heater efficiencies to the customer can be difficult if there are different fuel options. There is no Energy Star standard for electric. In a pure energy factor comparison, a gas water heater might be .64 while an electric might be rated at .92. But that's not the whole story.
An electric water heater with a 4,500-Watt element takes about twice as much time to recover as a gas water heater with 50,000 Btu/h input, notes McDonald. "We see homeowners going back to gas, or putting in a second electric tank."
Design improvements in recent years have improved the efficiency of electric water tanks. Manufacturers moved the inlet to the bottom and added insulation. They've added glass lining and heat traps. New element configurations optimize heating capability and efficiency, noted Bill Hewa, residential electric product manager for A.O. Smith, Fergus, Ont.
Heat pump water heaters, like the AO Smith Voltex, draw heat from their surroundings.
However, striving for efficiency isn't new, noted Lesage. In 1956 Quebec Hydro was struggling with power outages as everyone came home from work and jumped in the shower. This resulted in the development of the "Canadian style" twin-element electric water heater with a smaller element to provide the base load and a larger one that kicks in when demand is high.
Today, Giant's three-element EcoPeak water heaters work on the same principle. The bottom element is 800 Watts to cover the base load - the first 28 gallons - in a 60-gallon tank. Alone, it can provide about 72 gallons of DHW per day. The middle 3,000-Watt element kicks in when the demand is higher and then finally the 3,800 element at the top if additional hot water is required.
Ensuring that the water temperature remains consistent from top to bottom allows the elements to be run at a lower temperature, improving efficiency, while at the same time reducing scaling.
Bradford-White has taken a different approach. Its "Hydrojet" technology is basically a perforated inlet tube that forces the water to mix sooner, creating a quicker recovery and thus more efficient operation.
Rheem's Marathon water heater avoids scaling altogether with a plastic tank and jacket, which also provides substantially lower standby losses than a conventional steel tank.
The AO Smith Conservationist line features glass lining, which dramatically reduces the corrosive effect of hot water, along with additional insulation and heat traps to maximize efficiency.
The Rheem Marathon's unique plastic tank and jacket results in high efficiency and prevents scaling.
Heat pump water heaters
The new heat pump models offered by A.O. Smith, Rheem and General Electric are probably the ultimate in electric storage tank water heaters. Electricity consumption is roughly half of a conventional DHW heater.
Basically, they use an air-source heat pump that pulls heat from the room and dumps it at a higher temperature into the tank, operating like a refrigerator in reverse. They usually have electric resistance heating as backup. They operate best in a warm space like a furnace room and will tend to cool the room down. In fact the warmer the space the more efficient they become.
Installation is no more difficult than a conventional electric tank, reports Paul Gharghoury, Canadian market manager for Rheem Canada.
They cost about three times as much as a conventional electric tank, but in areas where electricity rates are high the payback can be relatively quick.
Bradford White's Hydrojet technology ensures better mixing of hot and cold water for quicker recovery.
As any plumber knows, electric water tanks are easy to install. Probably the most important step for the contractor is to determine the homeowner's lifestyle and budget. While the standard 40-gallon tank will meet the needs of most families, if there is a soaker tub or multi-jet shower in the home, a 60-gallon or larger is a must.
"If the homeowner can spend $40,000 on a shower, they can spend $800 on a water heater," remarked Lesage. "A water heater is one of the smallest expenses in a home, but it is the one that gives you the most for your money."
The plumber has to make sure there is enough power to operate the tank the customer chooses and that the cable is large enough to handle the power. Typically, there's a jump in cable size for any tank requiring more than 3,800 Watts.
Minimizing pipe runs by locating the tank in a central location, if possible, along with insulating the hot water lines will also boost efficiency, noted Hewa.
An evolving technology
The result is about 50 percent energy savings over a conventional electric DHW tank.
Electric tanks will continue to evolve. Lesage expects there will soon be 80-gallon models to handle the high-end bathrooms that stretch the capacity of a 60-gallon unit. As well, Giant is working on a high efficiency, high temperature glass-lined tank designed specifically for markets with time-of-use hydro rates.
And, says Rheem's McPherson: "We expect there will be more demand for residential electric just because of the way the efficiencies are moving." And with a tight economy, "Water heaters are still a replacement type business. If you can find a lower cost replacement solution, people tend to (adopt) it," he added.
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