TOKYO GAS TOP > Technical development > Low-carbon society > Promoting Eco-JOES as the de-facto standard for gas water heaters

Promoting Eco-JOES as the de-facto standard for gas water heaters

The maximum heating efficiency of conventional water heaters is approximately 80%. Eco-JOES (condensing gas water heater) improves this efficiency to approximately 95% thanks to its ability to recover latent heat from waste gas. This helps to reduce CO2 emissions and curb global warming. With the aim of not only installing Eco-JOES in new homes but also replacing conventional water heaters in existing homes, Tokyo Gas has continued to increase its product lineup, improve the ease of installation, expand drainage methods, reduce the size of equipment and lower costs.


Japanese gas companies as a whole have worked to promote wider adoption of Eco-JOES to date. However, a large number of conventional gas water heaters remain in use today. Through the development of technology that promotes Eco-JOES as an alternative to conventional gas water heaters when the latter need to be replaced, Tokyo Gas will promote Eco-JOES as the de-facto standard for gas water heaters, and accordingly contribute to a reduction in energy consumption and CO2 emissions.
Structural comparison between conventional gas water heater(left) and Eco-JOES (latent heat recovery-type system)


System Outline and Characteristics


1. Expansion of the line-up considering the replacement of water heaters in existing houses

In existing apartment buildings, utilities are often gathered together in pipe shafts (PS). This shaft represents dead space in a room and restricts the living space. The present lineup of Eco-JOES is not adequate enough to correspond to the replacement of all water heaters.
One way in which we have expanded our lineup is developing the slim-type Eco-JOES to replace old-style water heater models such as conventional slim-type water heaters and balanced-flue bath boilers.
Development of slim-type Eco-JOES

2. Development of drain processing technology

The Eco-JOES system generates acidic drain water while recovering latent heat; thus, the drain water is neutralized inside the system before being discharged. However, in many existing houses it is difficult to ensure a secure drainage channel at the time of installation.
To resolve this problem, we have introduced a " method of replacing to three pipes (utilizing a water heater with a drainage transport pump)" which is used to replace the two existing reheating pipes running from the pipe shaft to the bathroom with three pipes, one of which is the drain water pipe. Additionally, we have developed a "Eco-JOES with three-way valves for drainage," which has two three-way valve units (one in the water heater case, the other under the bathtub apron ) so that drain water is discharged into a bathroom drain via the existing reheating pipes.
 A mechanism of Eco-JOES with three-way valve drain processing
A mechanism of Eco-JOES with three-way valve drain processing
Standard Eco-JOES

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