Renewable Energy Systems
Case Study: Mr. Plumber and The Economic Case for Reducing Electric Water Heater Standby Losses.
Background: The relatively low initial cost of upright storage style residential electric water heaters makes them an attractive choice as a means to provide domestic hot water. Additionally, as their operation does not involve the combustion of fuels, they do not require on-site fuel storage or external venting.
Challenge: Because water heaters maintain a specified volume of water at temperatures typically no less than 120 degrees Fahrenheit (49 degrees Celsius), storage style water heaters continually lose heat through their internal insulation jacket (the space between the tank and the external metal casing) to the surrounding area. This heat loss is known as standby loss and is commensurate with the surface area of the tank, the temperature differential (i.e., the difference in temperature between the water and the ambient air), and the level of insulation of the internal jacket.
In response to the rising cost of conventional energy or by using renewable energy sources, manufacturers are producing water heaters with improved thermal storage characteristics. However, when standby losses are considered over the expected service life of a water heater, the cost of these losses can still exceed the initial cost of the water heater. The purpose of this project was to determine the economic viability of reducing the standby energy loss of a 151-litre upright storage style residential electrical water heater by wrapping it with an after-market insulation jacket. Two types of jackets were used – a reflective insulation jacket and a fibreglass insulation jacket.
Result:
Each jacket was monitored over a 7-day period. The reflective insulation jacket reduced standby loss by 10.9 percent, provided a simple payback of 3.1 years and a return on investment of 32.7 percent. The fibreglass insulation jacket reduced standby loss by 33.9 percent, provided a simple payback of 1.4 years and a return on investment of 70.1 percent. While the economic case is strong for the reflective insulation jacket, it is considerably stronger for the fibreglass insulation jacket therefore making it a better investment.
“At Mr. Plumber we are trying to do our part to protect the environment. We feel that every small step made by individuals and companies can make a collective difference.”
Glen Gardiner, Mr. Plumber/Blair LaPierre Inc. www.mrplumber.ca
1:28 pm
On demand gas water heaters are a more efficient way to heat domestic hot water. Living on an Island where Natural Gas is unavailable however, makes this choice more costly. Propane is more expensive and has a lower BTU content than Natural gas. This study was meant more to point out the advantages of insulating an existing electric hot water heater.