Monessen Hearth Natural Blaze Series Installation instructions

1
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
Models:
Installation/Owner’s Manual
Appliance Setup, Care and Operation
NOTICE: DO NOT discard this manual!
In the Commonwealth of Massachusetts installation must be
performed by a licensed plumber or gas tter.
See appliance installation manual for additional
Commonwealth of Massachusetts requirements.
INSTALLER: Leave this manual with party responsible for use and operation.
OWNER: Retain this manual for future reference.
Contact your dealer with questions regarding installation, operation or service.
• DO NOT store or use gasoline or other am-
mable 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.
- Leave the building immediately.
- Immediately call your gas supplier from
a neighbor’s phone. Follow the gas sup-
plier’s instructions.
- If you cannot reach your gas supplier, call
the re department.
• Installation and service must be performed
by a qualied installer, service agency, or the
gas supplier.
WARNING:
FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly
could result in serious injury, death, or
property damage.
NB18NV/PV
NB24NV/PV
NB18NIF/PIF
NB24NIF/PIF
Natural Blaze Series
• DO NOT install this unit in a bedroom or
bathroom.
810107
NB18/24 cover

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/192
Safety Alert Key:
• DANGER! Indicates a hazardous situation which, if not avoided will result in death or serious injury.
• WARNING! Indicates a hazardous situation which, if not avoided could result in death or serious injury.
• CAUTION! Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.
• NOTICE: Used to address practices not related to personal injury.
Table of Contents
Installation Standard Work Checklist ....................3
1 Product Specic & Important Safety Information
A. Appliance Certication ............................4
B. BTU Specications ...............................4
C. Gas Pressures ..................................4
D. High Altitude Installations ..........................4
E. Non-Combustible Materials Specication. . . . . . . . . . . . . . 4
2 Getting Started
A. Design and Installation Considerations ...............5
B. Tools and Supplies Needed ........................5
C. Inspect Appliance and Components .................. 5
D. Check Parts ....................................6
E. Installation Information ............................6
F. Adequate Combustion Ventilation Air .................7
3 Clearances & Height Requirements
A. Clearances & Height Requirements ..................9
B. Before Installing the Appliance ..................... 13
C. Damper Stop Installation .........................13
D. Assembly Procedure ............................14
4 Gas Information
A. Gas Line Connection ............................15
B. Fuel Type .....................................15
C. Gas Pressure .................................. 15
D. Gas Service Access .............................16
E. Check Gas Pressure ............................16
5 Electrical Information
A. General Information .............................17
B. Connect Optional Wall Switch or Thermostat ..........18
C. Connect Remote Receiver ........................19
D. Check System Operation ......................... 19
E. Wiring Requirements ............................20
F. Detailed Component Operating Instructions ..........21
6 Gas Log Set
A. Grate & Log Installation ..........................22
B. Log Placement (Berkley Oak) .....................23
C. Log Placement (Highland Oak) ....................25
D. Log Placement (Stoney Creek) ....................26
E. Log Placement (Beachcomber) ....................28
F. Flame Appearance ..............................29
G. Operating Instructions ...........................29
7 Owner’s Manual
A. Congratulations ................................31
B. Limited Lifetime Warranty .........................32
8 Product Specication Information
A. Application Certication ..........................35
B. BTU Specications ..............................35
9 Important Safety & Operating Information
A. Appliance Safety ...............................36
B. General Operating Parts .........................38
C. Fuel Specications ..............................38
D. Before Lighting Appliance. . . . . . . . . . . . . . . . . . . . . . . . . 38
10 Lighting Instructions
A. Millivolt .......................................39
B. Intellire Plus ODS (IFP) .........................42
C. Initial Use .....................................44
11 IntelliFire Plus
A. RC300 Remote Control ..........................45
12 Maintenance & Service
A. Maintenance: Frequency & Tasks .................49
B. Maintenance Tasks: Qualied Service Technician ..... 49
C. Burner Ignition & Operation .......................49
D. Cleaning & Servicing ............................50
13 Troubleshooting
A. Millivolt Control System .......................... 51
B. IntelliFire Plus ODS Ignition System ................52
14 Service Parts & Accessories
A. Service Parts ..................................54
B. Accessories ...................................72
C. Contact Information .............................74
NOTE: Monessen vent free gas logs are hand painted
for ultimate beauty and realism. As a result, some
variation in color and shading will occur from set to set.
This is intentional and designed to make each product
unique, as found in nature.

3
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
Installation Standard Work Checklist
Gas Section 4
Proper appliance for fuel type.
Leak check performed and inlet pressure verified.
Verified proper air shutter setting for installation type.
Customer:
Lot/Address:
Model (circle one): NB18NV,NB18PV,NB18NIF,NB18PIF
NB24NV,NB24PV,NB24NIF,NB24PIF
Date Installed:
Location of Fireplace:
Installer:
Dealer/Distributor Phone #
Serial #:
Comments: Further description of the issues, who is responsible (Installer/ Builder/ Other Trades, etc) and corrective
action needed _____________________________________________________________________________________
Comments Communicated to party responsible ____________________ by ______________________on ___________
(Builder / Gen. Contractor/) (Installer) (Date)
?YHW , ON F I SEY
___________________________
___________________________
___________________________
___________________________
___________________________
Gas Log Install Sections 2 and 5
Verified that the chimney has been cleaned. (pg. 13)
Verifi ed clearances to combustibles.
Gas Logs are leveled and secured.
See page 8 for adequate provisions for combustion and ventilation
air have been verified.
___________________________
___________________________
___________________________
___________________________
___________________________
Finishing Section 3
Verifi ed all clearances meet installation manual requirements.
Mantels and wall projections comply with installation manual requirements.
___________________________
___________________________
___________________________
___________________________
___________________________
Manual bag and all of its contents are removed and the log set
given to party responsible for use and operation.
Started log set and veried no gas leaks exist.
___________________________
___________________________
4619-982 08/19
 = Contains updated information.
Hearth & Home Technologies recommends the following:
• Photographing the installation and copying this checklist for your file.
• That this checklist remain visible at all times on the appliance until the installation is complete.
This standard work checklist is to be used by the installer in conjunction with, not instead of, the instructions contained in this
installation manual.
WARNING! Risk of Fire or Explosion! Failure to install appliance according to these instructions could
lead to a fire or explosion.
ATTENTION INSTALLER:
Follow this Standard Work Checklist
Embers & Logs Section 6
All packaging and protective materials removed (inside & outside of appliance).
Embers and logs installed correctly.
Accessories installed properly.
Electrical Section 5
Switch wires properly installed.

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/194
This product is listed to ANSI standards for "Unvented
Room Heaters” and applicable sections of "Gas Burning
Heating Appliances for Manufactured Homes" and "Gas
Fired Appliances for Use at High Altitude."
A. Appliance Certication
E. Non-Combustible Materials Specication
Material which will not ignite and burn. Such materials are
those consisting entirely of steel, iron, brick, tile, concrete,
slate, glass or plasters, or any combination thereof.
Materials that are reported as passing ASTM E 136,
Standard Test Method for Behavior of Materials in
a Vertical Tube Furnace at 750 ºC shall be considered
non-combustible materials.
NOT INTENDED FOR USE AS A PRIMARY HEAT SOURCE.
This appliance is tested and approved as either supplemen-
tal room heater or as a decorative appliance. It should not
be factored as primary heat in residential heating calcula-
tions.
NOTICE: This installation must conform with local codes.
In the absence of local codes you must comply with the
National Fuel Gas Code, ANSI Z223.1-latest edition in
the U.S.A.
1 Product Specic and Important Safety Information
B. BTU Specications D. High Altitude Installations
NOTICE: If the heating value of the gas has been reduced,
these rules do not apply. Check with your local gas utility
or authorities having jurisdiction.
When installing above 2000 feet elevation: Reduce input
rate 4% for each 1000 feet above sea level.
Check with your local gas utility to determine proper
orice size.
MODEL: NB18NV/PV, NB24NV/PV, NB18NIF/PIF
NB24NIF/PIF
LABORATORY: CSA
TYPE: Unvented Room Heater
STANDARD: ANSI Z21.11.2-2016 (Unvented Heaters)
ANSI Z21.60-2017∙CSA 2.26-2017 (Decorative
Gas Appliances for Installation in Solid-Fuel
Burning Fireplaces)
Models
Maximum
Input
BTU/h
Minimum
Input
BTU/h
Orice
NB18NV (0-2000 FT) 28,000 19,000 #38
NB18PV (0-2000 FT) 27,000 22,000 #52
NB24NV (0-2000 FT) 37,000 25,000 3.00 mm
NB24PV (0-2000 FT) 36,000 28,000 #49
NB18NIF (0-2000 FT) 28,000 19,000 #38
NB18PIF (0-2000 FT) 27,000 22,000 #52
NB24NIF (0-2000 FT) 37,000 25,000 3.00 mm
NB24PIF (0-2000 FT) 36,000 28,000 #49
NOTE: For LP models an external regulator is required
to reduce supply pressure to a maximum of 13" w.c.
NATURAL PROPANE (LP)
Inlet Minimum 5.0" w.c. 11.0" w.c.
Inlet Maximum 10.5" w.c. 13.0" w.c.
Gas Valve Manifold
Pressure Setting
3.5" w.c. 10" w.c.
Pilot Regulator 3.5" w.c. —
NATURAL GAS: An external regulator is required to reduce
supply pressure to a maximum of 101⁄2" w.c. on natural gas
systems operating at higher pressure.
PROPANE/LPG: An external regulator is required to reduce
supply pressure to a maximum of 13" w.c.
Pilot/ODS
The gas log heater is tted with a specially designed safety
pilot (ODS assembly) which senses the amount of oxygen
available in the room and shuts the gas log heater off if the
oxygen level begins to drop below a satisfactory level. The
pilot can only be relit when adequate fresh air is available.
C. Gas Pressures

5
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
2 Getting Started
A. Design and Installation Considerations
Installation MUST comply with local, regional, state and
national codes and regulations. Consult insurance carrier,
local building inspector, re ofcials or authorities having
jurisdiction over restrictions, installation inspection and
permits.
Before installing, determine the following:
• Where burner assembly and log set are to be installed.
• Gas supply piping.
• Whether optional accessories—devices such as a wall
switch or remote control—are desired.
• Approved wood burning masonry replace or vent-free
replace.
Improper installation, adjustment, alteration, service or
maintenance can cause injury or property damage. For
assistance or additional information, consult a qualied
service technician, service agency or your dealer.
Installation and service of this appliance should
be performed by qualied personnel. Hearth
& Home Technologies recommends HHT
Factory Trained or NFI certied professionals.
C. Inspect Appliance and Components
• Carefully remove the appliance and components from
the packaging.
• Logs are packaged and sold separately.
• Report to your dealer any parts damaged in shipment.
•Read all of the instructions before starting the instal-
B. Tools and Supplies Needed
Before beginning the installation be sure that the following
tools and building supplies are available.
• Tape measure
• Gloves
• Voltmeter
• Manometer
• Phillips screwdriver
• Safety glasses
• Flat blade screwdriver
• Soapy water solution for gas leak testing
• Electric drill and bits (1/4 in. magnetic)
• External regulator (for propane/LPG only & 1/2 psi
Natural gas system
• Piping which complies with local codes
• Pipe sealant approved for use with propane/LPG
(Resistant to sulfur compounds)
Hearth & Home Technologies disclaims any responsibility
for, and the warranty will be voided by, the following actions:
• Installation and use of any damaged appliance.
• Modication of the appliance.
• Installation other than as instructed by Hearth & Home
Technologies.
• Installation and/or use of any component part not approved
by Hearth & Home Technologies.
Any such action may cause a re hazard.
WARNING! Risk of Fire, Explosion or Electric Shock!
DO NOT use this appliance if any part has been under
water. Call a qualied service technician to inspect the
appliance and to replace any part of the control system
and/or gas control which has been under water.
• Manual shutoff valve
• Sediment trap
• Tee joint
• Pipe wrench
lation. Follow these instructions carefully during the
installation to ensure maximum safety and benet.
WARNING! Risk of Fire or Explosion! Damaged parts
could impair safe operation. DO NOT install damaged, in-
complete or substitute components. Keep appliance dry.
Gloves are recommended when handling
refractory and logs to prevent skin irritation
from loose bers. Logs are fragile; handle
with care.
CAUTION
WARNING: This product and the
fuels used to operate this product (liquid
propane or natural gas), and the products
of combustion of such fuels, can expose
you to chemicals including benzene, which
is known to the State of California to cause
cancer and reproductive harm. For more
information go to: www.P65Warnings.
ca.gov.

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/196
E. Installation Information
Use manufacturer's installation and clearance require-
ments as dened in their manual.
The NB18, 24, 30 series unvented room heaters are
approved for installation into the following unvented re-
boxes: MCUF, LCUF, GCUF, GRUF, BUF and Exacta.
The Natural Blaze Series unvented room heaters may
also be installed into a Ventless Firebox Enclosure for
Gas Fired Decorative Type Unvented Room Heaters per
ANSI Z21.91 (typically referred to as a "universal rebox"),
as long as rebox hearth dimensions meet the minimum
hearth dimensions shown below. See Figure 2.1.
A
C
D
B
Figure 2.1 - Minimum Dimensions for Engine, Logs &
Firebox
This appliance is for installation only in a solid-fuel
burning masonry or UL127 factory-built replace
or in listed ventless rebox enclosure. It has been
design certied for these installations.
Exception: DO NOT install this appliance in a factory-
built replace that includes instructions stating
it has not been tested or should not be used with
unvented gas logs.
WARNING
D. Check Parts
Verify contents to ensure you have received all parts. You
should have the following:
NB Models
• Unvented gas log burner assembly
• Two (2) bags of crushed volcanic rock
• Installation/operating instructions
• Two (2) Anchoring Screws
• Ceramic ber or refractory logs
• Rock wool
• Grate assembly
• On/off log switch assembly (MV models only)
• RC300 remote control (IFP models only)
• Double A batteries (IFP models only)
The following options may be used with the millivolt con-
trolled heater. These options are not packaged with the
log set.
• Hand-held remote with receiver (MV)
• Wall switch with 15' wire
• HILOKTN/P (an accessory kit for ame adjustment
from a hand held remote)
Carefully inspect the contents for shipping damage. If any
parts are missing or damaged, immediately inform the
dealer from whom you purchased the appliance. Do not
attempt to install any part of the appliance unless you
have all parts in good condition.
Placement in Fireplace with a Restrictive Barrier
The following are guidelines for placing a gas log set in a
replace that has a restrictive barrier on the replace for
vented appliance only. See Figure 2.2.
Height of Restriction
(x)
Minimum Depth of
Fireplace/Firebox
No Restriction 13"
0" to 3" 16"
Greater than 3" *
*Any barrier greater than 3" placed in front of the gas log set is not
recommended by the manufacturer.
NOTE: Non-combustible material such as refractory brick
may be used to line the oor of the replace in order to raise
the height of the gas log set in relation to a restrictive barrier.
If the unit is raised, the minimum height dimension listed
in the homeowner’s manual must be met or exceeded.
NOTE: If the log set is equipped with a remote receiver, a
restrictive barrier may reduce the battery life by increasing
the ambient temperature inside the replace. Placement
of the receiver outside of the replace will extend the
battery life.
Model A B C D
NB18 w/18" Log 26" 13" 18" 17"
NB24 w/24" Log 29" 13" 221⁄4" 17"
NB24 w/30" Log 33" 13" 251⁄4" 17"
NB18IF w/18" Log 281⁄2" 13" 201⁄4" 17"
NB24IF w/24" Log 31" 13" 251⁄4" 17"
NB24IF w/30" Log 35" 13" 251⁄4" 17"

7
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
Do not install the heater:
•Where curtains, furniture, clothing, or
other ammable objects are less than
36" from the front of the heater.
• In high trafc areas.
•In windy or drafty areas.
WARNING
WARNING
Gloves are recommended when handling
logs to prevent skin irritation from loose
bers. Logs are fragile—handle with care.
Barriers such as the bottom of a glass door frame
placed in front of a gas log set can change the air
ow characteristics of the replace which in turn
can cause the unit to overheat and malfunction when
installed as a vented log set.
WARNING
Glass door frames with adjustable louvers
should have the louvers fully open while
the unit is in operation
Depth of re-
place/rebox
(Refer to table)
The log set should be placed against
or as near as possible to the rear
wall of the replace/rebox.
Height of restrictive barrier caused by glass
door frames, recessed replaces, etc. from
the base or bottom surface of the unit.
(Refer to table)
Figure 2.2 - Reference Drawing of a Natural Flame Log Set in
an Enclosure with Glass Door or Barrier Installed
F. Adequate Combustion Ventilation Air
This heater shall not be installed in a conned space or
unusually tight construction unless provisions are provided
for adequate combustion and ventilation air.
The National Fuel Gas Code, (ANSI Z223.1/NFPA54),
denes a conned space as a space whose volume is less
than 50 cubic feet per 1,000 BTU per hour (4.8m3 per kw)
of the aggregate input rating of all appliances installed in
that space, and an unconned space as a space whose
volume is not less than 50 cubic feet per 1,000 BTU per
hour (4.8 m3 per kw) of the aggregate input rating of all
appliances installed in that space. Rooms communicat-
ing directly with the space in which the appliances are
installed, through openings not furnished with doors, are
considered a part of a conned space.
Unusually tight construction is dened as construction
where:
a. Walls and ceilings exposed to the outside atmosphere
have a continuous water vapor retarder with a rating of
1 perm (6 x 1011 kg per pa/sec-m2) or less with openings
gasketed or sealed, and
b. Weather stripping has been added to windows and
doors, and
c. Caulking or sealants are applied to areas such as joints
around window and door frames, between sole plates
and oors, between wall-ceiling joints, between wall
panels, at penetrations for plumbing, electrical and gas
lines and other openings.
The following formula can be used to determine the maxi-
mum heater rating per the denition of unconned space:
Refer to Figure 2.3.
BTU/Hr = (L1+ L2) Ft x (W) Ft x (H) Ft
50
Consider two connecting rooms with an open area
between, with the following dimensions:
L1 = 151/2 Ft., L2 = 12 Ft., W = 12 Ft., H = 8 Ft.
BTU/Hr = (151/2 + 12) x (12) x (8)
50
If there were a door between the two rooms the calculation
would be based only on the room with the heater.
BTU/Hr = (151/2) x (12) x (8)
50

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/198
If the area in which the heater may be
operated does not meet the required volume
for indoor combustion air, combustion and
ventilation air shall be provided by one
of the methods described in the National
Fuel Gas Code, ANSI Z223.1/NFPA 54, the
International Fuel Gas Code or applicable
local codes.
WARNING
W
H
Counter
Fireplace
Figure 2.3

9
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
3 Clearances and Height Requirements
Sidewall and ceiling clearances: The sides of the re-
place opening must be at least 16" from any combustible
wall. The ceiling must be at least 42" from the top of the
replace opening.
Heat resistant material (minimum requirements) with
no wooden mantel or other combustible projection:
To install the gas logs into a replace with no wooden
mantel, shelf or other combustible projection above the
replace opening, measure the heat resistant material
height, according to Figure 3.2 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 ue
damper open. Refer to “Installing Vented Applications”
found on page 13.
FP2254
measure heat resist
Heat resistant
Material
Measure
This
Distance
Heater in
Fireplace/
Firebox
Figure 3.2 - Measure Heat Resistant Material
Table A — Heat Resistant Material Requirements with No Mantel or Combustible Projection
Heat Resistant Material
Measurement
Requirements for Safe Installation
NB18 NB24
12" or more Hood not required Hood not required
8" or less than 12" Hood not required Extend heat resistant material to 12" or install hood. Figure 3.3
Less than 8" Extend heat resistant
material to 8” AND
install hood. Figure 3.3
Extend heat resistant material to 8" AND install hood Figure 3.5.
OR Extend heat resistant material to a height of at least 12".
16"
42"
Figure 3.1 - Sidewall and Ceiling Clearances
The dimensions shown in Figures 3.1 through
3.8 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 rebox,
minimum clearances, as specied by the ventless
rebox manufacturer, must be met.
Follow these instructions carefully to ensure safe
installation. Failure to follow instructions exactly
can create a re hazard.
WARNING
A. Clearances and Height Requirements

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/1910
Heat resistant material (minimum requirements) with
wooden mantel or other combustible projection:
To install the heater with a wooden mantel, shelf or other
combustible projection above, rst measure the heat resis-
tant material shown in Figure 3.3, then refer to Table B.
FP2255
measure heat resist
Hood
Heater in Fireplace
or Firebox
8" or More
of Heat
Resistant
Material
Figure 3.3 - Measuring Heat Resistant Material for Mantel
Table B - Heat Resistant Material Requirements Height and Mantel Location
Heat Resistant
Material
Measurement
Requirements for Safe Installation with Wooden Mantel, Shelf or other Combustible
Projection
NB18 NB24
12" or more Hood not required. Observe proles (side
elevations) shown in Figure 3.6 .
Hood not required. Observe prole (side
elevations shown in Figure 3.6 .
8" or less than 12" Install hood and observe proles shown
in Figure 3.5 OR Extend heat resistant
material to at least 12" and observe proles
shown in Figure 3.6.
Install hood and observe proles shown
in Figure 3.5 . OR Extend heat resistant
material to at least 12" and observe proles
shown in Figure 3.6.
Less than 8" Extend heat resistant to at least 8", install
hood and observe proles shown in Figure
3.5 . OR Extend heat resistant material to
at least 12" and observe proles shown in
Figure 3.6.
Extend heat resistant material to least 8",
install hood and observe proles shown
in Figure 3.5 . OR Extend heat resistant
material to at least 12" and observe proles
shown in Figure 3.6.

11
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
Figure 3.5 - Minimum Mantel Clearance with Hood — All
Models
Example: A mantel may project from the wall a maximum
of 21⁄2" at a minimum of 8" above the opening, and a
maximum of 6" at a minimum of 141⁄2" above the opening.
10"
8"
6"
2¹⁄₂"
8" 14" 20¹⁄₂" 24⁵⁄₈" 28"
FP2256
min. clearance no hood
Example: A mantel may project from the wall a maximum
of 21⁄2" at a minimum of 14" above the opening, and a
maximum of 6" at a minimum of 201⁄2" above the opening.
Figure 3.4 - Minimum Mantel Clearance with No Hood —
NB18
Heat
Resistant
Material
Heater in
Fireplace or
Firebox
FP2257
min clear with hood
10"
8"
6"
2¹⁄₂"
8" 14¹⁄₂" 18⁵⁄₈" 22¹⁄₂" 26"
12"
Heat
Resistant
Material
Heater in
Fireplace or
Firebox
Hood
Figure 3.6 -Minimum Mantel Clearance with No Hood —
NB18/24
Example: The bottom of the mantel may project from the
wall a maximum of 10" at a minimum of 28" above the
opening.
10" or less
12" min.
FP2260
min mantel 24
28"
Heat
Resistant
Material
Heater in
Fireplace or
Firebox

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/1912
The gas log heater must be installed at least 13⁄8" above
any combustible ooring material, such as carpeting or
tile, which is closer than 14" to the base of the replace.
The minimum distance must be maintained from the top
surface of carpeting, tile, etc. Figure 3.7
OR
The gas log heater may be installed nearer to the oor if a
minimum of 14" of noncombustible material such as slate
or marble is installed between the base of the replace and
the combustible ooring. Figure 3.8
Figure 3.7 - Minimum Clearance above Combustible
Flooring
FP2261
Min comb floor clear
Heater in Fireplace
or Firebox
Combustible
Material
13⁄8" Minimum
Figure 3.8 - Minimum Clearance above Combustible
Flooring with Noncombustible Material Installed at Base
of Fireplace
FP2262
Min noncomb floor clearance
14” Minimum
Heater in Fireplace
or Firebox
Combustible
Material
This Distance
May Now be
Less Than 13⁄8"

13
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
Before Fully Installing the Unit:
• Turn OFF the gas supply to the replace or rebox.
• Seal any fresh air vents and/or ash clean-out doors
located on the oor or wall of the replace. If left
unsealed, drafting may cause pilot outage or soot-
ing. Use a heat resistant sealant. Do not seal the
chimney ue damper.
Vented Application Installations —
NB & NBIF Only
Intellire Plus ODS (IFP) and millivolt controlled gas logs
may be installed as a vented decorative log set in com-
pliance with ANSI Z21.60 and National Fuel Gas Code,
Section 6.6. Since, the gas logs are operated with the
damper open, non-combustible material and minimum
mantel requirements do not apply.
B. Before installing the appliance:
• Turn off gas supply to replace or rebox.
• Have the replace oor and chimney professionally
cleaned to remove ashes, soot, creosote or other
obstructions. Have this cleaning performed annually
after installation.
•Seal any fresh air vents or ash clean-out doors
located on oor or wall of replace. If not, drafting
may cause pilot outage or sooting. Use a heat-
resistant sealant.
Install and operate the appliance as directed in this
manual.
C. Damper stop installation:
A damper stop must be provided with the unit. Contact your
dealer to obtain one. The damper stop must be installed as
shown in Figure 3.9 to prevent full closure of the replace
damper blade and provide a minimum 29 square inch ue
opening.
Figure 3.9 - Damper Stop Installation.
FP2263
Damper stop install
Damper Stop
Damper
Before installing in a solid fuel burning replace,
The chimney ue and rebox must be cleaned of
soot, creosote, ashes and loose paint by a qualied
chimney cleaner.
WARNING
This log set can be installed in a solid fuel burning
fireplace (masonry fireplace or manufactured
replace) with a working ue and constructed of
non combustible material or in a vent-free rebox.
Exception: DO NOT install this appliance in a factory-
built replace that includes instructions stating that
it has not been tested or should not be used with
unvented gas logs. This log set may be installed as
a vented log set.
WARNING
The use of thermostat is not allowed on vented log
application. It is only allowed on unvented room
heater classication.
WARNING
When this log set is installed in a vented application,
the damper must be clamped to be fully open.
WARNING
NOTE: The use of a thermostat is prohibited in vented
log installations.

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/1914
Figure 3.10 - Securing Heater to Floor of Fireplace/Firebox
D. Assembly Procedure
1. Center the burner assembly inside the fireplace or
firebox. Make certain that the front of the burner
assembly sits inside the front edge of the replace or
the rebox.
2. Anchor holes are located on the right and left sides of the
brackets attached to the engine base. After centering
the burner assembly correctly, mark the holes on the
replace or rebox oor. Drill two (2) 5/32” diameter holes
approximately 1 ¼” deep. Anchor the two anchoring
screws shipped with the unit using ¼” hex head chuck
and secure the burner assembly to the replace through
the holes drilled earlier. See Figure 3.10.
3. Anchor the grate to the replace/rebox oor using the
screws provided. See Figure 3.10.
Proper installation of the grate is essential to prevent
any movement of the gas logs and controls during
operation.
You must secure the gas log heater to the replace
oor. If not, the entire unit may move when you
adjust the controls. Movement of unit may cause
shifting of the gas logs which leads to sooting and
improper burning. Grate movement could cause a
gas leak.
Special care is required if you are installing the unit
into a sunken replace. You must raise the replace
oor to allow access to gas log controls. This will
ensure adequate air ow and guard against sooting.
Raise the fireplace floor using noncombustible
materials, as described in Placement in a Fireplace
with Restrictive Barrier on Page 6.
WARNING
Screw
Screw
Anchor Hole

15
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
4 Gas Information
A. Gas Line Connection
NOTICE: A qualied gas appliance installer must connect
the heater to the gas supply. Consult all local codes.
IMPORTANT: Hold heater valve rmly with a wrench to
prevent movement when connecting to inlet pipe.
Always use an external regulator for all propane/LPG
heaters and high pressure one to two-pound systems
only, to reduce the supply tank pressure to a maximum of
13" w.c. This is in addition to the internal regulator in the
heater valve.
The heater gas inlet connection is a 3/8" NPT at the valve.
On all control type units, the inlet connection is on the right
side of unit. To connect from the opposite side, route the
pipe around the back portion of the unit.
When tightening up the joint to the valve, hold the valve
securely to prevent movement.
Test all gas joints from the gas meter to the heater valve for
leaks using a gas analyzer or soap and water solution after
completing connection. DO NOT USE AN OPEN FLAME.
Check the gas pressure with the appliance burning and
the control set to HIGH.
Use new black iron or steel pipe. Internally tinned
copper or copper tubing can be used per National
Fuel Code, section 2.6.3, providing gas meets
hydrogen sulde limits, and where permitted by local
codes. Gas piping system must be sized to provide
minimum inlet pressure (Listed on Data Plate) at the
maximum ow rate (BTU/hr). Undue pressure loss
will occur if the pipe is too small.
A manual shutoff valve must be installed upstream
of the appliance. Union tee and plugged 1/8" NPT
pressure tapping point should be installed upstream
of the appliance.
WARNING
Connecting directly to an unregulated propane/
LPG tank can cause an explosion.
WARNING
CHECK GAS TYPE: The gas supply must be the
same as stated on the heater’s rating plate. If the
gas supply is different, DO NOT INSTALL THE
HEATER. Contact your dealer for the correct model.
WARNING
Figure 4.1 Gas Connection
B. Fuel Type
• This appliance is equipped for either natural or propane
gas. Field conversion is not permitted.
• Make sure the appliance is compatible with available gas
types.
C. Gas Pressure
• Optimum appliance performance requires proper input
pressures.
• Gas line sizing requirements will be determined in ANSI
Z223.1 National Fuel Gas Code in the USA.
• Pressure requirements are:
NATURAL PROPANE (LP)
Inlet Minimum 5.0" w.c. 11.0" w.c.
Inlet Maximum 10.5" w.c. 13.0" w.c.
Gas Valve Manifold
Pressure Setting
3.5" w.c. 10" w.c.
Pilot Regulator 3.5" w.c. —
WARNING! Risk of Fire or Explosion! High pressure
will damage valve. Low pressure could cause explosion.
• Verify inlet pressures. Verify minimum pressures when
other household gas appliances are operating.
• Install regulator upstream of valve if line pressure is
greater than 1/2 psig.
• Valve pressure taps are accessible by removing the right
side log. See Figure 4.2.

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/1916
Note: Have the gas supply line installed in accordance with
local codes, if any. If not, follow ANSI Z223.1. Installation
should be done by a qualied installer approved and/or
licensed as required by the locality. (In the Commonwealth
of Massachusetts installation must be performed by a
licensed plumber or gas tter).
Fire Risk.
Explosion Hazard.
High pressure will damage valve.
• Disconnect gas supply piping BEFORE
pressure testing gas line at test pressures
above 1/2 psig.
• Close the manual shutoff valve BEFORE
pressure testing gas line at test pressures
equal to or less than 1/2 psig.
WARNING
Depending upon local code, a manual gas shutoff, in
a readily accessible area may be required and located
upstream from the appliance.
D. Gas Service Access
FP2266
valve
Figure 4.2 - Pressure Test Point Location Millivolt Control
Test Port “OUT”
Intellire Plus ODS (IFP)
Check the gas pressure with the appliance burning and
the control set to HIGH.
The valve regulator controls the burner pressure which
should be checked at the pressure test point.
Turn captured screw counterclockwise two or three turns
and then place tubing to pressure gauge over test point.
Use test point “A” closest to gas inlet. After taking pres-
sure reading, be sure and turn captured screw clockwise
rmly to reseal. Do not over torque. Check for gas leaks.
See Figure 4.3.
Figure 4.3 Pressure Test Point Location
Test Port ‘A’
E. Check Gas Pressure
Millivolt
The valve regulator controls the burner pressure which
should be checked at the pressure test point.
Turn captured screw counter clockwise two or three turns
and then place tubing to pressure gauge over test point
(use test point “OUT” closest to control knob). After taking
pressure reading, be sure and turn captured screw clock-
wise rmly to re-seal. Do no over torque. Check for gas
leaks. See Figure 4.2.

17
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
5 Electrical Information
CAUTION
Label all wires before disconnecting when
servicing controls. Wiring errors can cause
improper and dangerous operation.
Do not connect wall switch to 110 V circuit.
WARNING
Electrical connections should only be performed
by a qualied, licensed electrician. Main power
must be off when connecting to main electrical
power supply or performing service. All wiring
shall be in compliance with all local, city and
state codes. The appliance, when installed,
must be electrically grounded in accordance
with local codes or in the absence of local
codes, with the National Electrical Code ANSI/
NFPA 70 (latest edition) and Canadian Electrical
Code, CSA C22.1.
WARNING
A. General Information
WARNING! Risk of Shock or Explosion! DO NOT wire
110-120 VAC to the valve or to the appliance wall switch.
Incorrect wiring will damage controls.
NOTICE: This appliance must be electrically wired and
grounded in accordance with local codes or, in the absence
of local codes, with National Electric Code ANSI/NFPA
70-latest edition.
• Wire the appliance junction box to unswitched 110-
120 VAC. This is required for proper operation of the
appliance.
• A 110-120 VAC circuit for this product must be protected
with ground-fault circuit-interrupter protection, in
compliance with the applicable electrical codes, when
it is installed in locations such as in bathrooms or near
sinks.
• Low voltage and 110/120 VAC voltage cannot be shared
within the same wall box.
Electrical Service and Repair
WARNING! Risk of Shock! Label all wires prior to dis-
connection when servicing controls. Wiring errors can
cause improper and dangerous operation. Verify proper
operation after servicing.
WARNING! Risk of Shock! Replace damaged wire with
type 105º C rated wire. Wire must have high temperature
insulation.
Accessories Requirements
• This appliance may be used with a wall switch, or optional
wall mounted thermostat and/or a remote control.
Wiring for optional Hearth & Home Technologies approved
accessories should be done now to avoid reconstruction.
Follow instructions that come with those accessories.

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/1918
The millivolt valve is a self-powered combination gas con-
trol THAT DOES NOT REQUIRE 110 VAC TO OPERATE.
B. Connect Optional Wall Switch or
Thermostat (vent free application only)
1. Use 18 awg, two-wire cable, 15 feet maximum length.
2. At one end of the cable, connect both wires to the wall
switch or thermostat. At the other end, connect one
wire to TP/TH and one wire to TH, using fork terminal
or connect the wall switch/thermostat to the two male
(0.25") terminals on the left side of the unit. The color
of the wires does not matter.
Figure 5.1 - Wiring Diagram
NOTE: Log switch wires are not factory connected. Connect log switch wires to the TP/TH and TH valve
terminals as shown.
FP2267
wiring diagram
Log Switch
On/Off Switch
or Optional Wall
Switch, Remote
or T-Stat
ODS Pilot
Millivolt
Valve
TH = 3
TP = 1
TP/TH = 2
ODS
Pilot
CAUTION
Label all wires prior to disconnection when
servicing controls. Wiring errors can cause
improper and dangerous operation. Verify
proper operation after servicing.
Thermopile
Wires

19
Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/19
C. Connect Remote Receiver
1. Set remote receiver. See instructions included in
receiver kit.
2. Unplug the two terminals for the log switch from the
valve, connect the piggy back terminal of the receiver
to the TH and TP/TH on the valve. Slide the terminal
of the log switch onto the piggy back terminal on the
receiver
NOTE: Do not allow wires to touch grate or burner.
NOTE: Heat reduces battery life. You can protect the
receiver and extend battery life by mounting receiver
in wall or other location outside the replace.
D. Check System Operation
The millivolt system and individual components may be
checked with a millivolt meter having a 0-1000 mV range.
Conduct each check shown in chart below by connecting
meter test leads to terminals as indicated.
1. Complete Millivolt System Check
(“A” Reading - Thermostat contacts CLOSED -
Control Knob “ON” - Main burner should turn
ON)
a. If the reading is more than 175 millivolts and the
automatic valve still does not come on, replace the
control.
b. If the closed circuit reading (“A” reading) is less than
175 millivolts, determine cause for low reading, pro-
ceed to Section B below.
2. Thermopile Output Reading Check
(“B” Reading - Thermostat contacts OPEN - Main
burner OFF)
1. Check gas pressure to the unit. If gas pressure is
within minimum and maximum on data plate, then
check pilot voltage, 500 millivolts minimum. If the
minimum millivolt reading is not obtainable, replace
pilot.
Figure 5.2 - Installing Remote Receiver
Check
Test To Test
Connect Meter Leads
to Terminals
Switch or Thermostat
Contacts Meter Should Read
A Complete System 2 and 3 Closed Minimum 175
BThermopile Output 1 and 2 Open Minimum 500
TP/TH = 2
TP = 1
TH = 3
Remote Wire
Connectors
Remote Wire
Connectors
Valve
Remote Receiver

Monessen • Natural Blaze Owner’s /Installation Manual • 4619-900 Rev. B • 11/1920
E. Wiring Requirements
Intellire™Plus ODS Ignition System Wiring
• Wire the appliance junction box to 110-120 VAC for
proper operation of the appliance.
WARNING! Risk of Shock or Explosion! DO NOT wire
IFP ODS controlled appliance junction box to a switched
circuit. Incorrect wiring will override IFP ODS safety lock-
out.
• Refer to Figure 5.4, IFP ODS Wiring Diagram.
• This appliance is equipped with an Intellire™ Plus
control valve which operates on a 6 volt/1.5 AMP system.
• Install 4 AA cell batteries into the battery pack before use.
See Figure 5.3
THERMOCOUPLE MODULE
PILOT
19093-Thermocouple Module Wire
CONTROL MODULE
I
S
BATTERY PACK
6V DC
RED
BLACK
BROWN
BROWN/BLACK
OPTIONAL ON/OFF
SWITCH
RC300 4.5V DC
(AAA X 3)
FLAME
MODULATION
BLACK
(GROUND)
ORANGE
(PILOT)
GREEN
(MAIN)
THERMOCOUPLE
ORANGE
IGNITOR
GRAY
19026-GM931 Control Box ODS
THERMOCOUPLE
IGNITOR
WHITE
RED
Figure 5.4 IntelliFire™ Plus ODS Wiring Diagram (Battery Only)
Figure 5.3 Battery Pack Location
Battery Pack