การติดตั้งระบบท่อระบบทำความร้อนและระบบปรับอากาศ

This class includes the installation of plumbing, heating and air-conditioning systems, including additions, alterations, maintenance and repair.

This class includes:
- installation in buildings or other construction projects of:
* heating systems (elect

This class excludes:
- installation of electric baseboard heating, see 4321