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HSChapter 84
U.S. imports of auxiliary plant for use with steam, vapor, and central heating boilers (HS 840410) totaled $22.4M in July 2026, traded with 22 countries.
Importers of Auxiliary Plant for Use with Steam, Vapor, and Central Heating Boilers paid $110K in duties in July 2026 — an effective duty rate of 0.6% on $19.7M in dutiable value, based on actual customs collections rather than the published tariff schedule. Auxiliary Plant for Use with Steam, Vapor, and Central Heating Boilers imports of $22.4M in July 2026 ran 115% above the year-to-date monthly average of $10.4M.
Last updated: July 2026 dataEconomizers — heat-recovery devices that preheat feedwater using exhaust gases — are specifically broken out at the 10-digit level (8404100010) from other auxiliary plant (8404100050), making correct sub-classification critical for importers of boiler support equipment. Canada is the leading supplier to the US market under this heading, with Thailand and Israel also notable sources. Auxiliary plant in this heading serves power generation, industrial process heating, and district energy systems, so end-use documentation can be important when equipment crosses multiple application categories.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
39 shipments/mo
An economizer is specifically a heat-recovery device that uses flue or exhaust gases to preheat boiler feedwater, improving thermal efficiency. Under HTS 8404100010, economizers for use with boilers of headings 8402–8403 are separately classified. Other auxiliary equipment — such as superheaters, soot blowers, and gas recovery apparatus — falls under 8404100050 when not meeting the economizer definition.
There is no mandatory admissibility review by a regulatory agency for auxiliary boiler plant as industrial equipment. However, large capital equipment may require coordination with the buyer's engineering team to confirm compliance with ASME or other applicable pressure-vessel standards, and certain power-plant components may be subject to export controls in the country of origin.
Subheading 1 of 3 in heading 8404
Subheading 840410 · $22.4M of $28.8M
Supplier Network
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Imports · July 2026
origin
Thailand and Canada together supply 97% of it.
customs district
destination
entry
rate provision · imports
12.1% enters free of duty; the effective duty rate is 0.49%.
ImportsExports
Imports
$22.4MYoY · Pro
Exports
$1.4MYoY · Pro
12-mo low · imports
YoY · ProThrough July 2026. Source: U.S. Census Bureau.
HS10 import codes under this HS6 parent, each with its own page. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Dutiable Share | Duty Collected |
|---|---|---|---|---|---|
| 8404100050 | Aux Plt for Use With Blrs,Hdg 8402-8403,not Ecnmzr | $22.2M | 0.36% | 88.05% | $79K |
| 8404100010 | Economizers for Use With Boilers of Head 8402-8403 | $155K | 20.10% | 65.24% | $31K |
HS10 export codes under this HS6 parent, each with its own page. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 8404100050 | Aux Plt for Use With Blrs,Hdg 8402-8403,not Ecnmzr | $812K |
| 8404100010 | Economizers for Use With Boilers of Head 8402-8403 | $571K |
Import lines come from the U.S. Harmonized Tariff Schedule and export lines from Schedule B. The two are numbered by different agencies, so the same 10-digit code can appear in both tables describing a different product.