111043-03 - 9/21
SteamMax
Models:
• STMX075
• STMX100
• STMX125
• STMX150
• STMX175
WARNING
This boiler must only be installed, serviced, and repaired by a qualified installer, service agency or gas
supplier. Improper installation, adjustment, alteration, service or maintenance can cause severe personal
injury, death, or substantial property damage. For assistance or additional information, consult a qualified
installer, service agency or gas supplier. Read these instruction carefully before installing.
!
Installation, Operating and Service Instructions for
Manual Contents Page
1. Qualified Installer, Service Agency or Gas Supplier
Read Before Proceeding ......................3
2. User/Homeowner Read Before Proceeding .......4
3. Specifications ...............................5
4. Locating Boiler .............................10
5. Preparing Boiler .............................14
6. Venting ....................................15
7. Steam Piping ...............................18
8. Gas Piping .................................22
9. Electrical ..................................24
10. System Start-Up and Checkout ................31
11. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
12. Before Leaving Jobsite .......................40
13. Service and Maintenance .....................41
14. How it Works ...............................45
15. Troubleshooting ............................49
16. Service Parts ...............................56
Appendix A Steam Boiler Skimming ...............71
Appendix B Indirect Water Heater .................72
Appendix C McDonnell & Miller 150S-MD Auto Reset
LWCO/Pump Control ............................74
• STMX200
• STMX250
• STMX299
• STMX350
• STMX399
• STMX450
• STMX500
• STMX550
WARNING
Attention Installer - Affix these instructions
adjacent to boiler. Provide model number and
serial number when seeking information and
support.
Attention Building Owner - Retain these
instructions for future reference. Contact a
qualified installer, service agency or gas
supplier for all issues and support.
!
• Steam Boiler
• Cast Iron
• Chimney Vent
• Gas Fired
NOTICE: Knock-Down Boilers: These instructions
address installation and controls. Assembly is
addressed in separate instructions shipped with
knock-down boilers.
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