Monessen Hearth Magnum Unvented Vent-Free Fireboxes MCUF42D SERIES User Manual
Magnum, Warnings, Unvented vent-free fireboxes

For use with a listed gas-fired 
unvented decorative room heater 
not to exceed 40,000 BTU/hr. Do 
not build a wood fi re.
READ AND SAVE THESE INSTRUCTIONS
WARNINGS
If the information in this manual is not followed exactly, 
a fi re or explosion may result causing property damage, 
personal injury or loss of life.
– Do not store or use gasoline or other fl ammable
vapors and liquids in the vicinity of this or any other 
appliance.
– WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any
phone in your building.
• Immediately call your gas supplier from a neighbor's
phone. Follow the gas supplier's instructions.
• If you cannot reach your gas supplier, call the fi re
department.
– Installation and service must be performed by
a qualified installer, service agency or the gas 
supplier.
MODELS:
MCUF36D and MCUF42D SERIES
MAGNUM
UNVENTED
VENT-FREE
FIREBOXES
INSTALLATION AND
OPERATING INSTRUCTIONS
Carefully review the instructions 
supplied with the decorative type 
unvented room heater for the mini-
mum fi replace size requirement.
DO NOT INSTALL AN APPLIANCE 
IN THIS FIREBOX UNLESS THIS 
FIREBOX MEETS THE MINIMUM 
DIMENSIONS REQUIRED FOR 
THE INSTALLATION.
WARNINGS
If the information in this manual is not followed 
exactly, a fire or explosion may result causing 
property damage, personal injury or loss of life.
– Do not store or use gasoline or other fl ammable
vapors and liquids in the vicinity of this or any 
other appliance.
– WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use
any phone in your building.
• Immediately call your gas supplier from a
neighbor's phone. Follow the gas supplier's 
instructions.
• If you cannot reach your gas supplier, call the
fi re department.
– Installation and service must be performed by
a qualifi ed installer, service agency or the gas 
supplier.
WARNINGS
