Natural Gas Tankless Water Heaters
Energy has been a hot topic over the past few months and New Brunswickers are now as interested as ever in technologies that can reduce their energy consumption. As energy prices continue to rise and we learn more about our impact on the environment, the need for high efficiency products is becoming more and more important.
As it relates to the home, the obvious opportunity is reducing the heating load first. However, once you’ve insulated, replaced windows and improved your heating system, how do you further reduce your need for energy?
The answer: your domestic hot water heating system.
Domestic hot water can account for up to 30% of your home’s energy consumption. Furthermore, new homes are being built as tight as ever and with homeowners wanting the luxuries of whirlpool tubs and waterfall showers, domestic hot water loads can easily surpass heating as the highest energy user.
A technology now seeing resurgence is natural gas fired tankless water heaters. This technology has undergone major changes in recent years and is gaining popularity as a reliable, efficient source of seemingly endless hot water, all within a small footprint. Let’s take a closer look at this technology and how it compares to other natural gas units.
When it comes to domestic hot water heaters, the technology mainstay has been tank type water heaters. At a high level, these units operate by heating a large vessel of water and keeping it hot until the homeowner needs it. Here is a list of the pros and cons of natural gas fired units.
• Reliable
• Provides ample hot water in first hour
• Low initial cost
• Space / location limitations
• Standby losses, although minimal
• Little hot water after first hour, until tank heats up
• Low efficiency (E.F. of 0.60)
• Possibility of significant water damage if unit fails
The natural gas industry has used tank type water heaters successfully for decades. They are easy to install and do a great job in providing hot water. However, unless a condensing version is installed, they are inefficient and don’t meet the needs of an energy conscious home owner.
The new kid on the block is tankless or on-demand water heaters. These units operate by circulating only the amount of water needed through a heat exchanger which quickly heats up the water and sends it to the tap. The unit’s natural gas burner only fires when it senses flow (when a tap is turned on) and shuts down once flow stops (once the tap is turned off).The result is only the amount of hot water you need, when needed, with no large volume of hot water kept on standby.
• Continuous supply of hot water; no running out if you are the last one in the shower
• High efficiency (E.F. of 0.85) with condensing units up to an E.F. of 0.96
• Saves space, mounts on wall
• No standby losses
• Less risk for water damage caused by unit failure
Tankless water heaters are rapidly becoming the efficient solution for meeting the hot water needs of today’s family. The seemingly endless supply of hot water in a compact and light weight unit is ideal for homeowners who also want to make a positive contribution to the environment.
However, with all new technologies come challenges. These units are more expensive than tank type water heaters, but the initial cost is paid back with the annual savings it generates. Also, tankless water heaters can provide endless hot water, but only within the flow rate capacities of the unit. Based on local ground water temperatures, typical units can provide hot water at temperatures between 4.5 to 5.9 gpm at 105F, depending on the size of the unit.
With all the hype about this technology, some people have branded these units as “instantaneous”, leading to expectations of hot water right out of the tap. This is not the case. Some units require a little longer than usual to provide hot water when compared to a tank type water heater. Some manufacturers have overcome this issue by installing a small buffer tank to maintain a small amount of hot water on hand to offset any delays.
This tank also addresses the “cold water sandwich” effect. This occurs when a homeowner turns off his hot water for a short period of time. Once they turn it back on, a slug of cold water has time to flow through the unit and to the tap before the unit can heat it up to temperature. The end result is hot water, the slug of cold water, followed by more hot water - or a cold water sandwich. Again, most manufacturers have implemented their own solution to mitigate this effect.
With a bit of education, highlighting capabilities and limitations, the right expectations can be set which, in turn, will lead to happy customers.
Overall, tankless units present a great opportunity to provide unlimited hot water in a manner which is good for the environment and the wallet.