Clearances And Height Requirements - Monessen Hearth NB24 Installation And Operating Instructions Manual

NB18/NB24 Gas Log Set
WARNING
The dimensions shown in Figures 3 through 11 and
defined in the fireplace manufacturer's instructions
are minimum clearances to maintain when installing
this heater. Left and right clearances are determined
when facing the front of the heater.
When heater is installed into a ventless firebox,
minimum clearances, as specified by the ventless
firebox manufacturer, must be met.
Follow these instructions carefully to ensure safe
installation. Failure to follow instructions exactly
can create a fire hazard.
Sidewall and ceiling clearances: The sides of the fire-
place opening must be at least 16" from any combustible
wall. The ceiling must be at least 42" from the top of the
fireplace opening.
16"
Figure 3 -
Sidewall and Ceiling Clearances
Table A — Heat Resistant Material Requirements with No Mantel or Combustible Projection
Heat Resistant Material
Measurement
12" or more
8" or less than 12"
Less than 8"
Monessen • NB18/24 Gas Log Set Installation/Owner's Manual • 81D0107 • Rev E • 04/18
42"
FP2253
NB18
Hood not required
Hood not required
Extend heat resistant

CLEARANCES AND HEIGHT REQUIREMENTS

Heat resistant material (minimum requirements) with
no wooden mantel or other combustible projection:
To install the gas logs into a fireplace with no wooden
mantel, shelf or other combustible projection above the
fireplace opening, measure the heat resistant material
height, according to Figure 4 and TABLE A.
Heat resistant materials such as slate and marble must be
at least 1/2" thick. Sheet metal should not be installed
onto combustible material.
IMPORTANT: If you cannot meet these minimum clear-
ances you must operate the heater with chimney flue
damper open. Refer to "Installing Vented Applications"
found on page 17.
Figure 4 -
Measure Heat Resistant Material
Requirements for Safe Installation
Hood not required
Extend heat resistant material to 12" or install hood. Figure 4
Extend heat resistant material to 8" AND install hood Figure 5.
OR Extend heat resistant material to a height of at least 12".
Heat resistant
Material
Measure
This
Distance
Heater in
Fireplace/
Firebox
FP2254
FP2254
measure heat resist
NB24
7