Majestic • MER36MN, MER42MN Installation Manual • 2599-980 Rev. B • 5/23
24
NOTICE:
Install appliance on hard metal or wood surfaces
extending full width and depth.
DO NOT
install directly on
carpeting, vinyl, or any combustible material other than
wood.
WARNING! Risk of Fire!
Maintain specified air space
clearances to appliance and vent pipe:
• Insulation and other materials must be secured to prevent
accidental contact.
• The chase must be properly blocked to prevent blown
insulation or other combustibles from entering and
making contact with fireplace or chimney.
• Failure to maintain airspace may cause overheating and
a fire.
Figure 3.14 Exterior Chase - Minimum Height Requirements
D. Constructing the Appliance Chase
A chase is a vertical box-like structure built to enclose the
gas appliance and/or its vent system. In cooler climates
the vent should be enclosed inside the chase.
NOTICE:
Treatment of ceiling firestops and wall shield
firestops and construction of the chase may vary with the
type of building. These instructions are not substitutes
for the requirements of local building codes. Therefore,
you MUST check local building codes to determine the
requirements to these steps.
NOTICE:
Where required by code, install only sprinkler
heads with a sprinkler activation temperature classified
as Extra High.
•
Sprinklers inside of chase: Keep sprinkler head away
from vent and chimney.
•
Heat Management applications: Maintain 36 inches of
clearance to openings from which heat is discharged
such as convection slots, passive heat registers, heat
zone registers, etc. Refer to Section 6.B for Heat
Management options allowed for this appliance.
Chases should be constructed and insulated in the same
manner as the thermal envelope of the home based on
the code requirements for that climate zone to prevent air
leakage and draft problems. The chase is an extension of
the building thermal envelope.
To further prevent drafts and air leakage, the wall shield
and ceiling firestops should be sealed with caulk with
a minimum of 300 ºF continuous exposure rating to
seal gaps. Gas line holes and other openings should
be sealed with caulk with a minimum of 300 ºF continu
-
ous exposure rating or stuffed with unfaced insulation. If the
appliance is being installed on a cement surface, a layer of
plywood may be placed underneath to prevent conducting
cold up into the room.
Minimum height requirements for an exterior chase on a top-
vented appliance are shown in Figure 3.14. Reference Fig
-
ure 4.5 for additional clearances.
3 IN. MIN.
* NOTE: If overhang is less than 2 inches, clearance from top of
termination cap to bottom of overhang may be 0 inches.
A - Measured from back of vent cap to end of overhang
B - Measured from bottom of overhang to top of termination cap
C - Measured from bottom of appliance to combustible surface
Vinyl Siding Shield (TRAP-VSS) Information
TRAP-VSS required if overhang (A) is greater than 3 inches but less
than 5 inches and B dimension is less than 18 inches.
TRAP-VSS recommended if either of the below is true:
- Overhang (A) is less than 5 inches (to combat water infiltration)
- A vinyl overhang is present
A
B*
C
