Tank versus Tankless Water Heaters
admin January 30th, 2012
A desire to reduce our energy consumption in our homes continues to generate new energy efficient products. Recently there has been a push to use water heaters which only use power when the demand for water is stimulated, known as tankless water heaters. I have often wondered if this type of water heater is actually more efficient in power and water usage than the traditional type.
Canada Mortgage and Housing Corporation (CMHC) recently conducted a study to determine the impact that replacing a conventional hot water heater with a gas-fired tankless heater had on water and energy consumption in the home. 23 households were monitored and this is what it showed.
The results of the study showed that gas consumption was reduced by 46%; however, water consumption increased by about 2%. The reason: It takes time to heat the water to the set point and any cold water that is still in the pipes needs to be pushed out. The burner only ignites if a larger amount of water is run through the system, so you have to run the water for a while in order to get hot water; All of this uses more water.
Heating water accounts for about 20% or more of an average household’s annual energy
expenditures, so there is a savings in gas consumption with these tankless systems. However, tankless water heaters need both electricity and gas to operate so your electric bill will be higher. Maintenance is another factor since calcium accumulates in the unit and needs to be cleaned out every couple of years. In addition, the cost of these units is considerably higher than the traditional tank water heater.
Most tank water heaters work with only gas so if there is a gas interruption, you still have a tank full of hot water. With tankless models, you will be without hot water during a power outage as well.
In the final analysis you may not be saving as much as you might think between the gas cost, the electricity cost, the cost of the unit, maintenance and the extra water cost. However, they do take up much less room so they are a great solution for smaller spaces. Perhaps the best solution is still solar powered water heaters but that’s another topic.
Here are some of the companies who manufacture tankless water heaters.
Bosch Therm Ultra-Low NOx, Navien, Noritz, Rinnai. A competent contractor can advise you on the size and model that would work best for you.