Heat Pump Patents: Who Leads, Where Filings Are Flattening 2026
- Filing has plateaued, not grown. annual filings peaked at 124 in 2023 after sitting near 111 in 2022, with 2017 already at 118 — a decade of roughly flat output rather than a growth curve.
- The core claim territory is narrow. F25B refrigeration and heat-pump claims account for 2,839 of 3,135 records, meaning most of the field's activity sits in one IPC subclass rather than spread across the eight tracked here.
- Momentum has stalled at the top. Several of the most consistently active filers, including Carrier, Mitsubishi Electric and Daikin, show zero filings in the latest tracked year — a lag effect as much as a retreat.
Filing growth compares 2021 (116 records) with 2024 (111) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 3,135 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This dataset tracks patent families addressing heat pump systems and technology, filtered to records that combine heat pump terminology with technical claim language on coefficient of performance, defrost control, low ambient operation, variable speed compressors and refrigerant charge, and classified under F25B30, F24H4 and F25B13. The corpus spans 3,135 patent families published between 2015 and mid-2026, giving a decade-scale view of where claim activity has concentrated and where it has thinned out.
Because publication typically lags filing by around eighteen months, the most recent year in any trend line understates real activity — 2026's low count reflects a partial year and pending publications, not a sudden drop in filing.
Filing trend and technology composition
Two views matter here: how filing volume has moved year over year, and how that volume splits across the IPC subclasses that touch heat pump technology.
A decade of flat-to-declining output
Filings ran at 118 in 2017, climbed to a peak of 124 in 2023, and sat at 111 at the 2022 midpoint — a pattern of plateau rather than sustained growth. Combined with the falling 2024–2026 counts (expected given publication lag), the underlying signal is a mature filing base rather than an expanding one.
Concentration in refrigeration and heat-pump claims
F25B (refrigeration and heat pumps) carries 2,839 of the 3,135 records — well ahead of F24H fluid heaters (685), F24D domestic heating (522) and F24F air conditioning (460). Smaller counts in F28D heat exchangers (158), C09K materials (129) and B60H vehicle heating (77) mark adjacent areas with comparatively light claim density.
Shares are the percentage of the 3,135 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Heat Pump Systems and Technology with Eureka
This page is one run against one query. Ask Eureka your own question about heat pump systems and technology and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited prior art in this corpus
Refrigerant charge management in a heat pump water heater — NORDYNE, LLC
Heat pumps that heat or cool a space and that also heat water, refrigerant management systems for such heat pumps, methods of managing refrigerant charge, and methods for heating and cooling a space and heating water. Various embodiments deliver refrigerant gas to a heat exchanger that is not needed for transferring heat, drive liquid refrigerant out of that heat exchanger, isolate that heat exchanger against additional refrigerant flowing into it, and operate the heat pump while the heat exchanger is isolated.Filed as US8756943B2, granted 2014-06-24.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20100122545A1 | Tetrafluoropropene compositions and uses thereof | 253 |
| 2 | US6138466A | System for cooling electric vehicle batteries | 240 |
| 3 | US4420947A | Heat pump air conditioning system | 186 |
| 4 | US5758514A | Geothermal heat pump system | 178 |
| 5 | US5056329A | Heat pump systems | 177 |
| 6 | US7313926B2 | High efficiency absorption heat pump and methods of use | 158 |
| 7 | US4720981A | Cooling of air conditioning control electronics | 145 |
| 8 | US5927088A | Boosted air source heat pump | 142 |
| 9 | US5224357A | Modular tube bundle heat exchanger and geothermal heat pump system | 137 |
| 10 | US4882908A | Demand defrost control method and apparatus | 135 |
Citation counts are drawn from a searched corpus and skew toward older, more-cited records; treat them as a measure of influence rather than current relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once filing volume, IPC composition and citation activity are read together.
Growth has plateaued
Filing volume sat at 118 in 2017 and peaked at only 124 in 2023, with 111 at the 2022 midpoint. That is a flat trend line across nearly a decade, not the acceleration typical of an emerging technology.
One subclass dominates
F25B refrigeration and heat-pump claims account for the large majority of records. Adjacent subclasses such as B60H vehicle heating (77) and C09K materials (129) carry far lighter claim density, suggesting where prior art is thinner.
US and Europe lead intake
The United States (922) and the EPO (498) receive the largest share of filings, with Japan (399), WIPO/PCT (272), China (223) and Canada (176) following. Filing strategy in this field still runs primarily through US and European offices.
Older filings still anchor the art
The most-cited record in this corpus dates to refrigerant chemistry rather than system architecture, a reminder that citation leaders in a searched corpus tend to be older filings rather than the newest technical approaches.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to heat pump systems and technology, with the prior art for and against each one.
Who is filing, and where activity has stalled
Filing activity concentrates among a small group of established HVAC and refrigerant manufacturers, several of which show no filings in the most recent tracked year — consistent with publication lag rather than an actual pullback.
Momentum has cooled across leaders
Carrier, Mitsubishi Electric, Panasonic and Daikin each show zero filings in the latest tracked year, with Carrier and Rheem-affiliated filers registering a -100% year-on-year change. Given the roughly eighteen-month publication lag, this reads as pending disclosures rather than abandonment.
Co-assignment is limited but tight where it exists
Only ten co-assignee pairs appear across the corpus. The strongest pairing, an individual inventor-assignee combination, appears 36 times, well ahead of corporate pairings such as Daikin's domestic and European entities at 10 co-filings.
Named-inventor assignees are active
The strongest co-assignee relationship in the dataset pairs an individual inventor with a matching entity, a pattern distinct from the corporate co-filing seen among larger manufacturers such as Denso and its research affiliate.
| Assignee | Recent year | YoY |
|---|---|---|
| Carrier Corporation | 0 | -100% |
| Mitsubishi Electric Corporation | 0 | — |
| Panasonic Corporation | 0 | — |
| Daikin Industries, Ltd. | 0 | — |
| Rheem Manufacturing Company | 0 | -100% |
| JIN KUM SOO | 0 | — |
| Denso Corporation | 0 | -100% |
| Jin Kum Soo | 0 | — |
Where to take this analysis
The filing trend and IPC composition point to specific next steps depending on whether the goal is freedom-to-operate, portfolio strategy or new filing.
Check freedom-to-operate against the top-cited records
The highest-citation records in this corpus, several dating to the 1980s and 1990s, remain foundational prior art for system architecture and refrigerant chemistry claims. Any new filing in core heat pump cycles should be checked against these first.
Run a freedom-to-operate check in Eureka →Watch for renewed filing from stalled leaders
Several top assignees show zero filings in the latest year, which publication lag makes ambiguous — it could mean paused R&D or simply pending disclosures. Tracking these assignees over the next two publication cycles will clarify which.
Set up assignee tracking in Eureka →Explore the lighter-claimed adjacent subclasses
B60H vehicle heating and C09K materials carry far fewer records than the core F25B subclass, which may reflect genuine white space or simply narrower search terms. Either way, a targeted claim search in these subclasses is worth the time before filing.
Explore white space in Eureka →Common questions about heat pump patents
This dataset tracks 3,135 patent families published between 2015 and mid-2026 that combine heat pump terminology with technical claim language on defrost control, refrigerant charge and related topics, classified under F25B30, F24H4 and F25B13. Annual filings ran at 118 in 2017 and peaked at 124 in 2023, with a midpoint of 111 in 2022. The 2024–2026 counts appear lower mainly because publication lags filing by roughly eighteen months, so recent years are still filling in rather than reflecting a real drop.
Filing activity concentrates among established HVAC and refrigerant manufacturers including Carrier, Mitsubishi Electric, Panasonic and Daikin, alongside individual inventor-assignees with notable co-filing activity. Several of these leading names show zero filings in the most recent tracked year, which given publication lag likely reflects pending disclosures rather than an actual exit from the field. Reviewing the full assignee ranking alongside recent-year momentum gives a clearer picture than either figure alone.
The F25B subclass, covering refrigeration and heat pumps generally, accounts for 2,839 of the 3,135 records in this corpus, making it by far the densest claim territory. Fluid heaters and water heaters (F24H) and domestic heating systems (F24D) follow at 685 and 522 records respectively. Vehicle heating and air conditioning (B60H) and specialty materials (C09K) show much lighter filing density, at 77 and 129 records, making them worth a closer look for open claim space.
Patent applications are typically published around eighteen months after filing, so any trend line's final one to two years will always understate actual filing activity — those applications exist but have not yet published. In this dataset, the drop from 124 filings in 2023 to much lower figures by 2026 should be read in that light rather than as evidence of declining R&D investment. The safer read of momentum is the three-to-four-year trend leading up to the most recent complete year, not the final partial year itself.
Based on IPC composition, the subclasses with comparatively lower filing density relative to the dominant F25B category include B60H (vehicle heating and air conditioning, 77 records) and C09K (materials for refrigerants and related applications, 129 records). These lighter counts can indicate genuine under-claimed territory, particularly around vehicle-integrated heat pump loops and refrigerant-material co-claims, though they may also simply reflect narrower matching search terms. A targeted prior-art search within these subclasses is the right next step before relying on this as a filing strategy.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.