The patent dispute between boiler specialist corporations Kiturami and Kyungdong Navien has reignited. As Kyungdong Navien reorganized its patents amid a conflict over core technology used in condensing boilers, Kiturami launched additional action to invalidate them. Kyungdong Navien succeeded in maintaining the patents, but the dispute is expected to drag on.
According to a compilation of ChosunBiz reporting on the 7th, Kiturami and Kyungdong Navien are said to be pursuing lawsuits at the Intellectual Property High Court to overturn trial decisions in correction-invalidation proceedings over two patents for a "heat exchanger unit."
In April, the Intellectual Property Trial and Appeal Board dismissed in full Kiturami's petitions for correction-invalidation trials against Kyungdong Navien's heat exchanger unit patents. Kiturami filed suit with the Intellectual Property High Court seeking to overturn the IPTAB decisions. In patent disputes, the IPTAB serves as the court of first instance, followed by the Intellectual Property High Court, with the Supreme Court rendering the final decision.
A heat exchanger unit is a device inside a boiler that transfers heat generated in the combustion process to water to produce heating water and hot water. It determines the energy efficiency and performance of condensing boilers. Unlike conventional boilers, condensing boilers improve energy efficiency by also using the latent heat generated when water vapor in exhaust gas condenses.
The two companies have been at odds over heat exchanger units since 2023. At the time, Kyungdong Navien sought a preliminary injunction to bar patent infringement, saying Kiturami had used its heat exchanger technology for condensing boilers without authorization. In 2024, Kiturami filed a patent invalidation trial, and in September that year, the Intellectual Property Trial and Appeal Board ruled two of Kyungdong Navien's four patents invalid, one partially invalid, and one valid.
Kyungdong Navien then began work to supplement the patents that had been ruled invalid or partially invalid. In May last year, it filed correction trials to partially supplement and revise two patents and received decisions granting the requests four months later. A correction trial is a procedure in which, while maintaining the basic framework of a patent, the claims are narrowed or the language is clarified; it is used by patent holders to tidy up the scope of their rights.
Through the corrections, Kyungdong Navien specifically identified the arrangement structure of fins—metal plates that increase heat transfer area—and the sections in which the internal cross-sectional area of the heat exchanger decreases or is maintained, and it won recognition of validity.
After the correction trial requests were granted, Kiturami filed a trial in October last year seeking to invalidate them. It argued there was no inventiveness because the technology could be implemented by combining prior art such as published domestic and overseas patents.
However, the Intellectual Property Trial and Appeal Board found that the sections where the internal cross-sectional area of the heat exchanger decreases, the fin arrangement structure, and the parallel flow-path configuration are differentiated from prior art. It did not accept Kiturami's claims, saying Kyungdong Navien's patent composition could not be readily derived from existing published technologies alone.
An industry official said, "Because the heat exchanger is a technology that determines the efficiency and performance of condensing boilers, the business value of the patents is also high," adding, "If the patents are recognized as valid, they could affect future infringement lawsuits, so it will be hard for either side to back down easily."