Heat Pump Defrost Control Patents: Top Companies & Trends 2026
- Filing is concentrated at the top. The five most active assignees account for 219 of 410 records in scope — 53.4% of the field — with a long tail of single- and few-filing entrants behind them.
- Filing activity kept climbing through the last complete year. Volume rose from 41 records in 2021 to 48 in 2024, a 17% increase, after peaking at 74 records in 2022.
- Control-logic classes are thin relative to the mechanical core. G05B and G05D control classes cover 6.8% and 4.4% of records respectively, far below the 37.3% carried by the core refrigeration class F25B.
Filing growth compares 2021 (41 records) with 2024 (48) — 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 410 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks 410 published records matching defrost-cycle control language inside heat-pump and vapor-compression refrigerant-circuit claims, filed between 2015 and the 2026 data cut-off. The scope centres on how a system detects frost formation on an outdoor coil and decides when and how to run a defrost cycle — sensor placement, timing logic, and the control assemblies that trigger the switch — rather than the refrigerant circuit or compressor hardware in general.
Publication lags filing by roughly 18 months, so counts for 2025 and 2026 are still filling in and should not be read as a slowdown. The 2024 figures are the most recent that can be treated as complete, and they show continued growth against 2021 rather than a plateau.
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Filing trend and technology composition
Two views of the same 410-record set: how filing volume has moved year over year, and which IPC subclasses the claims actually sit in.
Filing trend, 2017–2026
Recorded filings rose from 13 in 2017 to a peak of 74 in 2022, before easing to 48 in 2024 — still 17% above the 2021 level of 41. The 2025–2026 figures are understated because publication has not caught up with filing.
Technology composition by IPC subclass
F25B (refrigeration and heat pumps) and F24D (domestic heating systems) each cover more than a third of the 410 records, with F24F air conditioning and F24H water heaters close behind — evidence that defrost control claims are being filed across adjacent appliance categories, not confined to one product line. Control-specific classes G05B and G05D sit well below the mechanical classes, at 6.8% and 4.4% of records respectively. Since a single record can carry several IPC codes, these shares add up to more than 100%.
Shares are the percentage of the 410 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Heat Pumps — Air-Source Heat-Pump Defrost Control Patent Landscape with Eureka
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Try EurekaRepresentative and most-cited filings
Defrost Cycle Control Assembly In A Heat Pump — US20200309444A1
A defrost cycle control assembly uses a first sensor to measure temperature near the top of an outdoor heat exchanger, a second sensor near the bottom, and a third sensor for ambient temperature. A controller initiates the defrost cycle based on the top-portion and ambient readings when they indicate frost formation at the top of the exchanger, where the first sensor sits.Filed by Rheem Manufacturing Company, published 2020-10-01.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20070012052A1 | Interactive control system for an HVAC system | 348 |
| 2 | US7296426B2 | Interactive control system for an HVAC system | 169 |
| 3 | US20060185373A1 | Interactive control system for an HVAC system | 155 |
| 4 | US4882908A | Demand defrost control method and apparatus | 135 |
| 5 | US8550368B2 | Interactive control system for an HVAC system | 117 |
| 6 | US4328680A | Heat pump defrost control apparatus | 114 |
| 7 | US5319943A | Frost/defrost control system for heat pump | 109 |
| 8 | US20080073440A1 | Interactive control system for an HVAC system | 104 |
| 9 | US7784291B2 | Interactive control system for an HVAC system | 100 |
| 10 | US20140034284A1 | Interactive Control System for an HVAC System | 90 |
Citation counts favour older records simply because they have had longer to accumulate citations inside this corpus — treat them as a signal of influence on the field, not as a ranking of current technical importance.
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Browse MCP servers →What the numbers mean for filing strategy
Three patterns stand out once the assignee ranking, the filing trend and the IPC composition are read together.
The top of the field is dense, not the whole field
The five most active assignees hold 219 of the 410 records in scope, and the ranked ten extend that to 262 records, or 63.9%. Below that line the ranking thins quickly into single- and few-filing entrants, which is where freedom-to-operate work tends to find room.
Growth held through the last complete filing year
Filing volume peaked at 74 records in 2022 and eased afterward, but the 2024 total of 48 still sits 17% above 2021. Because publication lags filing by around 18 months, the visibly lower 2025–2026 counts are an artefact of the pipeline, not evidence of a cooling field.
Control logic is thinly claimed relative to the mechanical core
F25B, the core refrigeration and heat-pump class, appears on 37.3% of the 410 records, and F24D domestic heating on 35.4%. The control-specific classes G05B and G05D cover only 6.8% and 4.4% respectively, suggesting that a large share of defrost-control claims are still written as mechanical or sensor claims rather than as dedicated control-algorithm claims.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to heat pumps — air-source heat-pump defrost control patent landscape, with the prior art for and against each one.
Who is filing, and where the gaps sit
The assignee ranking spans equipment manufacturers, controls specialists and newer heating-service entrants, with filing concentrated among a handful of large HVAC and refrigeration groups and a long tail of smaller filers.
A single filer holds well over a third of the top-five total
The leading assignee's 151 records dwarf the fifth-place total of 11, which sets the shape for the rest of the ranking: a steep drop-off after the leader, then a gradual taper through the ranked field.
The gap narrows fast past the top five
Fifth place holds 11 records and tenth place holds 6 — a much shallower drop than between first and fifth place, indicating a genuinely competitive mid-field rather than a two-tier structure.
Filing offices skew toward the US, UK and Japan
The United States leads receiving offices with 121 filings, ahead of the United Kingdom at 61 and Japan at 47, with the EPO, Australia and WIPO PCT routes each in the 29-43 range. That spread points to a technology being protected across several major heating and appliance markets rather than concentrated in one jurisdiction.
| Assignee | Recent year | YoY |
|---|---|---|
| Octopus Energy Heating Ltd | 0 | -100% |
| Emerson Electric Co. | 0 | — |
| OCTOPUS ENERGY LTD | 0 | — |
| Carrier Corporation | 0 | — |
| Honeywell International Inc. | 0 | — |
| Swegon AB | 0 | — |
| Rheem Manufacturing Company | 0 | — |
| MIXERGY LTD | 0 | — |
Where to take this analysis
The dataset points to a field with a concentrated top tier and comparatively thin control-logic claims — two starting points for a closer, company-specific or claim-specific review.
Run a freedom-to-operate check on control logic
With G05B and G05D control classes covering only 6.8% and 4.4% of the 410 records, a claim-by-claim review of sensor-fusion and algorithmic defrost-timing approaches is likely to surface less blocking prior art than a review of mechanical sensor-placement claims would.
Explore this landscape in EurekaTrack the leading assignee's recent filings
The top-ranked assignee holds more than a third of all 410 records; monitoring its most recent publications, once the 2025-2026 lag closes, will show whether it is extending its lead in mechanical claims or moving into the thinner control-logic space.
Set up assignee tracking in EurekaCommon questions about this landscape
This landscape identifies 410 published records matching defrost-cycle control language within heat-pump and vapor-compression refrigerant-circuit claims, filed between 2015 and the 2026 data cut-off. That figure counts publications, not underlying inventions, since a single invention can generate several related publications across jurisdictions. Because publication lags filing by roughly 18 months, the true count of recently filed inventions in 2025 and 2026 is understated in this total.
Filing is concentrated at the top: the five most active assignees together hold 219 of the 410 records in scope, or 53.4% of the field, and the ten most active hold 262 records, or 63.9%. The leading assignee alone holds 151 records, well ahead of the fifth-ranked filer at 11. Below the top ten, the ranking extends across 100 companies with a long tail of few-filing entrants, which is typically where openings for new entrants sit.
Filing volume rose from 41 records in 2021 to 48 in 2024, a 17% increase, after peaking at 74 records in 2022. The apparent decline in 2025 and 2026 is a publication-lag artefact rather than a real slowdown, since patent publication typically trails filing by around 18 months. Treat 2024 as the most recent year with a reliable, largely complete count.
The 410 records span several IPC subclasses beyond core refrigeration: F25B (refrigeration and heat pumps) appears on 37.3% of records, F24D (domestic heating) on 35.4%, F24F (air conditioning and ventilation) on 29.5%, and F24H (water heaters) on 26.1%. Dedicated control classes G05B and G05D are much thinner, at 6.8% and 4.4% respectively, suggesting defrost-control inventions are still mostly framed as mechanical or sensor claims. Because records can carry multiple IPC codes, these shares add up to more than 100% and should not be read as a breakdown of a single whole.
The clearest gap is in dedicated control-algorithm claims: G05B and G05D cover only 6.8% and 4.4% of the 410 records, far below the mechanical and sensor-placement classes that dominate filings. Sub-areas such as predictive or model-based defrost timing, multi-zone frost-sensing arrays, and machine-learning-based frost prediction appear comparatively under-claimed relative to the dense mechanical core. A first claim in these areas would need to tie a specific data input, such as compressor load or multi-point sensor fusion, to a defrost-trigger decision rather than claiming the sensor hardware alone.
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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.