UK SIC 2007 · 43221
Plumbing, heat and air-conditioning installation
UK plumbers, heating engineers, and HVAC contractors, domestic and commercial. Includes boiler installations, central heating, AC fit-outs, and ventilation systems. Distinct from 43222 (other heat installation, niche industrial work).
~65,000 active UK ltds filed under this code on Companies House.
Related SIC codes
43210, Electrical installation43222, Other heat installation43229, Other plumbing-related installation activitiesWho uses this code in B2B outreach
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Where SIC 43221 clusters in the UK
About SIC 43221
Are gas-safe heating engineers a separate SIC?
No, gas-safe registration is a regulatory status, not a SIC distinction. UK heating engineers all file 43221 regardless of which fuel types they're certified for.
How seasonal are SIC 43221 prospects?
Heavily, winter (Sept-Feb) is the busy season. Outreach targeting plumbers tends to perform better in spring/summer when they have more inbox attention.
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