Donghong
A thermal window opener that needs no power and no wiring: a sealed cylinder expands as the greenhouse warms and pushes the vent open, and a return spring closes it as the air cools. Single spring for 7–14 kg vents, double spring for 15–25 kg, 50 mm stroke, opening from 25–27 °C and fully open at 30 °C. Registered in 2021 in Dali, Nanhai, Foshan; registry read done, scope covers building metal-fitting and window manufacture. Open items are on the page: no import-export clause, bracket patents held by an individual, material and warranty wording that disagree, and no test report sighted.
One mechanism, two load bands, and the numbers printed.
Single-Spring Thermal Window Opener (Y01)
For lighter vents: rated in the quotation for a vent sash of 7–14 kg. Temperature-driven, 50 mm working stroke, no electricity, battery or air supply. Mounted on the single bracket that is the subject of design patent ZL 2025 3 0593059.5 (Y01).
Double-Spring Thermal Window Opener (Y02)
For heavier vents: rated for a vent sash of 15–25 kg. Same cylinder and stroke, with a second return spring, on the double bracket that is the subject of design patent ZL 2025 3 0593058.0 (Y02).
Replacement Thermal Cylinders
The introduction states the temperature rod unscrews from the opener, and recommends taking the cylinder off at sub-zero temperatures. A replacement or winter-storage cylinder is therefore a separate line item a buyer can ask for; no separate listing or MOQ has been provided.
Colour and Private-Label Options
The quotation offers five colours for custom spraying on top of the standard finish, at an extra cost per unit, and states that regular colours can be customised. No logo, packaging or instruction-sheet options are printed.
What the registry confirms, and what stays open.
Registered for Building Metal-Fitting and Window Manufacture
The registry read (2026-09-24, official source) records a scope that includes, in its own words, 建筑用金属配件制造 (building metal-fitting manufacture), 门窗制造加工 (door and window manufacture and processing), 金属结构制造 (metal structure manufacture), 家具零配件生产 (furniture fittings) and engineering R&D. A window-vent actuator sits inside that scope.
Opening Curve Published, Not Just ‘Automatic’
The introduction prints the three temperatures a grower plans around: starts to open at 25–27 °C, fully open at 30 °C, closes at 22–24 °C, with a working range of −20 to 60 °C. It also states plainly what the opener cannot do: neither the response speed nor the thresholds can be adjusted.
Two Load Bands Matched to Vent Weight
Single spring 7–14 kg, double spring 15–25 kg, 50 mm stroke. The introduction adds that the push force has to be matched to both the sash weight and wind-pressure resistance, and that the force of a thermal type varies with the temperature difference — the right caveat for a buyer sizing vents.
Bracket Designs Under Patent — Held by an Individual
Three granted Chinese patents cover the brackets: utility model ZL 2025 2 2173417.4 (a window-opener bracket structure, granted 2026-09-01) and design patents ZL 2025 3 0593058.0 and ZL 2025 3 0593059.5 (the Y02 double and Y01 single brackets, granted 2026-04-28). All three are held by a natural person, not by the registered company; no assignment or licence to the company has been seen.
No Import-Export Wording in the Scope
The registered scope names manufacture and R&D only. It contains no 货物进出口 (import and export of goods) clause. Whether the company exports under its own customs registration or through an agent is not established; ask before you agree on shipping terms.
Small Registered Team
The registry records 4 people on social insurance, registered capital of RMB 100,000 with paid-in capital not disclosed, and a registered address that is a self-declared address (住所申报) in the Dali industrial area of Nanhai.
One Administrative Penalty and Three Personnel Changes
The registry risk scan records one administrative penalty in the self-risk category (the scan labels the reason only as ‘other’; the decision itself has not been read), no peripheral or historical risk items, and three advisory items for changes of key personnel. The latest registry approval is dated 2026-06-11.
Material and Warranty Wording Disagree
The wholesale quotation says ‘all-aluminum construction’ and a 3-year warranty with free replacement if the cylinder leaks oil. The product introduction says the temperature rod is galvanised steel and gives a 5-year warranty. Both are reproduced here; which one applies to an order is to be confirmed in writing.
What was checked — and what the check found.
The registry read is done: status, scope, capital, insured headcount and the risk record come from an official registry source read on 2026-09-24, and the credit-code check digit was recomputed locally. The three patent certificates were supplied and read; they name an individual as patentee, not the company. Everything else on this page is read off the company’s own product introduction and wholesale quotation and is reproduced, not verified. No test report, material declaration or certification has been sighted. For a product whose whole promise is that a sealed cylinder keeps working season after season, the cycle and leak test behind the warranty is the first document a buyer will ask for. This page will be updated when documents are provided.
A Nanhai metal-fitting company with one product done in detail, read off its registry record and its own sheets.
Donghong is the trading name of Foshan Donghong Technology Co., Ltd. (佛山市东虹科技有限公司), registered on 2021-07-26 in the Dali industrial area of Nanhai District, Foshan — the aluminium-profile and door-and-window hardware belt of Guangdong. An official registry read on 2026-09-24 confirms active (存续) status, RMB 100,000 of registered capital with paid-in capital not disclosed, four people on social insurance, and a registered scope covering engineering R&D, building metal-fitting manufacture, furniture fittings, door and window manufacture and metal structures.
Its product is the thermal window opener used on greenhouse vents: a sealed temperature-driven cylinder with a return spring, offered in a single-spring version for 7–14 kg vents and a double-spring version for 15–25 kg, both on a 50 mm stroke. The introduction publishes the opening curve — 25–27 °C to start, 30 °C fully open, 22–24 °C to close — and the wholesale quotation, printed in English and Russian, gives an MOQ of 500 units, free samples on freight collect and five custom spray colours.
Four things are disclosed rather than smoothed over. The registered scope has no import-export clause. The three bracket patents are held by an individual, not by the company. The quotation and the introduction disagree on material and on warranty length. And no test report, material declaration or certification has been sighted. The registry risk scan records one administrative penalty, whose details have not been read, and three changes of key personnel.
Registered in 2021, patents granted in 2026.
Company registered in Nanhai, Foshan
Registered 2021-07-26 in the Dali industrial area of Nanhai with a scope in building metal fittings, windows and metal structures (registry read).
Bracket patents filed
One utility-model and two design applications on the opener brackets filed on 2025-10-10 and 2025-10-14, by an individual.
Design patents granted
Design patents for the Y01 single and Y02 double brackets granted 2026-04-28.
Latest registry approval
Last approval date 2026-06-11; the advisory record lists three changes of key personnel.
Utility patent granted; joins CMH
Utility model on the bracket structure granted 2026-09-01. Official registry read done 2026-09-24, surfacing the open items on this page.
Where a thermal opener earns its place.
Hobby and Garden Greenhouses
Roof and side vents on glass and polycarbonate greenhouses where there is no power at the vent; the opener works through the season without a controller.
Commercial and Farm Greenhouses
Supplementary passive ventilation on vents that are not motorised, as a fail-safe when power or controllers fail.
Sunrooms and Conservatories
Top-hung vents that should open on a hot afternoon without anyone at home.
Cold Frames and Plant Houses
Small lids and hatches in the lighter single-spring band.
Industrial Building Ventilation
Named in the introduction for factory-building ventilation; sizing against the sash weight and wind load is the buyer’s to confirm.
Natural Smoke-Vent Windows (claimed)
The introduction names natural smoke-vent windows linked to fire systems. No fire-safety certification or test report has been sighted; treat this use as unconfirmed.
Sourcing guides for this category
Importing from China: The Compliance Checklist by Market
What Documents to Request From a Chinese Supplier Before Your First Order
How to Request a Sample from a Chinese Factory (Without Getting Burned)
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Frequently Asked Questions
How does a thermal window opener work?
A sealed cylinder holds a fill that expands as it warms. As the greenhouse heats up, the expansion pushes the piston rod out and opens the vent; as it cools, the fill contracts and an external return spring pulls the vent closed. It is a purely physical reaction, so no electricity, battery, controller or compressed air is needed.
At what temperature does it open and close?
The product introduction states it starts to open at 25–27 °C, is fully open at 30 °C and closes at 22–24 °C, with a working range of −20 to 60 °C. Neither the thresholds nor the response speed can be adjusted. The introduction recommends taking the cylinder off at sub-zero temperatures.
Which model do I need?
Weigh the vent sash. The single-spring model is rated for 7–14 kg and the double-spring model for 15–25 kg, both on a 50 mm stroke. The introduction adds that wind pressure on the open vent has to be allowed for as well as weight, so on exposed sites size up.
Is this listing CMH-verified?
Yes, on the registry check: an official registry read on 2026-09-24 confirms active status and a registered scope that includes building metal-fitting and window manufacture. That verification covers the registry facts only. It does not cover the product claims, the warranty, the export route, the patent licence or any certificate — all of which are open and are set out on this page.
Who owns the patents?
The three patent certificates supplied — one utility model on the bracket structure and two designs for the single and double brackets — name a natural person as patentee, not the company. That is common in small Chinese firms, but if you are building a private-label range on these brackets, ask for the licence or assignment from the patentee to the company before you rely on it.
Can they export directly?
The registered scope contains no import-export wording. Many small manufacturers ship through an export agent or register with customs separately. Ask which route will be used, and who will appear as exporter on the documents, before you agree an Incoterm.
Is it 3 years or 5 years of warranty?
The documents disagree. The wholesale quotation offers 3 years with free replacement if the cylinder leaks oil; the product introduction says 5 years. The material wording also differs — all-aluminium in the quotation, galvanised-steel rod in the introduction. Get the warranty term and the bill of materials confirmed in writing on the order.
Talk to Donghong directly.
Send your vent weight and size, the opening direction, the climate at the site, the quantity and the destination market. Ask for the cycle-life and leak test behind the warranty, the material of the cylinder, rod and brackets, the patent licence from the patent holder, and how the goods will be exported. None of those is confirmed on this page.