Desa VM42P Quick start guide

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MODELS M36(B,H), M42(B,H), VM36(B,H) AND VM42(B,H)
NATURAL GAS
MODELS M36P(B,H), M42P(B,H), VM36P(B,H) AND VM42P(B,H)
PROPANE/LP GAS
B-VENT DECORATIVE GAS FIREPLACE
OWNER’S OPERATION AND INSTALLATION MANUAL
FOR YOUR SAFETY
— Do not store or use gasoline or any other flammable
vapors or 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 fire
department.
— Installation and service must be performed by a quali-
fied installer, service agency or the gas supplier.
WARNING: If the information in these instructions is
not followed exactly, a fire or explosion may result
causing property damage, personal injury or death.

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WARNING: Improper installation, adjustment, altera-
tion, service or maintenance can cause injury or prop-
erty damage. Refer to this manual for correct installation
and operational procedures. For assistance or addi-
tional information consult a qualified installer, service
agency or the gas supplier.
NOT FOR USE WITH SOLID FUEL
CHECK LOCAL CODES PRIOR TO INSTALLATION
SAVE THIS BOOK
This book is valuable. In addition to instructing you on how
to install and maintain your appliance, it also contains infor-
mation that will enable you to obtain replacement parts or
optional accessory items when needed. Keep it with your
other important papers.
This appliance may be installed in an aftermarket*, per-
manently located, manufactured (mobile) home, where
not prohibited by state or local codes.
This appliance is only for use with the type of gas indi-
cated on the rating plate.
This appliance is not convertible for use with other
gases, unless a certified kit is used.
*Aftermarket: Completion of sale, not for purpose of resale, from the manufacturer.
TABLE OF CONTENTS
Safety Information ............................................... 3
Unpacking ........................................................... 4
Introduction .......................................................... 4
Selecting Location ............................................... 5
Product Specifications ......................................... 6
Pre-Installation Preparation ................................. 7
Venting Installation .............................................. 9
Installation ..........................................................11
Operating Fireplace ........................................... 19
Inspecting Burners ........................................... 20
Cleaning and Maintenance ................................ 21
Wiring Diagram .................................................. 22
Service Hints ..................................................... 22
Technical Service .............................................. 22
Replacement Parts ............................................ 22
Troubleshooting ................................................. 23
Illustrated Parts Breakdown and Parts List ....... 26
Accessories ....................................................... 31
Warranty Information ............................ Back Page

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108795-01N 3
SAFETY INFORMATION
WARNING: This product
contains and/or generates
chemicals known to the State
of California to cause cancer or
birth defects or other reproduc-
tive harm.
IMPORTANT: Read this owner’s
manual carefully and completely
before trying to assemble, op-
erate or service this fireplace.
Improper use of this fireplace
can cause serious injury or death
from burns, fire, explosions,
electrical shock and carbon
monoxide poisoning.
DANGER: Carbon monoxide
poisoning may lead to death!
This fireplace is a vented product. This fireplace
will not produce any gas leakage into your home if
properly installed. This fireplace must be properly
installed by a qualified service person. If this unit is
not properly installed by a qualified service person,
gas leakage can occur.
Carbon Monoxide Poisoning: Early signs of
carbon monoxide poisoning resemble the flu, with
headaches, dizziness or nausea. If you have these
signs, the fireplace may not have been installed
properly. Get fresh air at once! Have fireplace
inspected and serviced by a qualified service
person. Some people are more affected by carbon
monoxide than others. These include pregnant
women, people with heart or lung disease or
anemia, those under the influence of alcohol and
those at high altitudes.
Propane/LP gas and natural gas are both odorless.
An odor-making agent is added to each of these
gases. The odor helps you detect a gas leak. How-
ever, the odor added to these gases can fade. Gas
may be present even though no odor exists.
Make certain you read and understand all warnings.
Keep this manual for reference. It is your guide to
safe and proper operation of this fireplace.
WARNING: Any change to
this fireplace or its controls can
be dangerous.
1. This appliance is only for use with the type
of gas indicated on the rating plate. This ap-
pliance is not convertible for use with other
gases unless a certified kit is used.
2. For propane/LP fireplace, do not place propane/
LP supply tank(s) inside any structure. Locate
propane/LP supply tank(s) outdoors. To prevent
performance problems, do not use propane/LP
fuel tank of less than 100 lbs. capacity.
3. If you smell gas
• shut off gas supply
• 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
neighborʼs phone. Follow the gas supplier's
instructions
• if you cannot reach you gas supplier, call the
fire department.
4. Never install the fireplace
• in a recreational vehicle
• where curtains, furniture, clothing or other
flammable objects are less than 42" from
the front, top or sides of the fireplace
• in high traffic areas
• in windy or drafty areas
5. This fireplace reaches high temperatures. Keep
children and adults away from hot surfaces to
avoid burns or clothing ignition. Fireplace will
remain hot for a time after shutdown. Allow
surfaces to cool before touching.
6. Carefully supervise young children when they
are in the room with fireplace.
7. A hearth extension is not required with this
appliance. If one is installed, it is for aesthetic
purposes only and does not have to meet the
standard requirements.
8. Turn fireplace off and let cool before servicing
or repairing. Only a qualified service person
should install, service or repair this fireplace.
Have fireplace inspected annually by a quali-
fied service person.
9. You must keep control compartments, burn-
ers and circulating air passages clean. More
frequent cleaning may be needed due to ex-
cessive lint and dust from carpeting, bedding
material, etc. Turn off the gas valve and pilot
light before cleaning fireplace.
10. Have venting system inspected annually by a
qualified service person. If needed, have vent-
ing system cleaned or repaired. See Cleaning
and Maintenance, page 21.

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11. Keep the area around your fireplace clear of
combustible materials, gasoline and other
flammable vapor and liquids. Do not run fire-
place where these are used or stored. Do not
place items such as clothing or decorations on
or around fireplace.
12. Do not use this fireplace to cook food or burn
paper or other objects.
13. Do not use any solid fuels (wood, coal, paper,
cardboard, etc.) in this fireplace. Use only the
gas type indicated on fireplace nameplate.
14. This appliance, when installed, must be electri-
cally grounded in accordance with local codes
or, in the absence of local codes, with the
National Electrical Code, ANSI/NFPA 70 or
the Canadian Electrical Code, CSA C22.1.
15. Do not obstruct the flow of combustion and
ventilation air in any way. Provide adequate
clearances around air openings into the combus-
tion chamber along with adequate accessibility
clearance for servicing and proper operation.
16. Do not install fireplace directly on carpeting,
vinyl tile or any combustible material other
than wood. The fireplace must set on a metal
or wood panel extending the full width and
depth of the fireplace.
17. Do not use fireplace if any part has been ex-
posed to or under water. Immediately call a
qualified service person to arrange for replace-
ment of the unit.
18. Do not operate fireplace if any log is broken.
19. Do not use a blower insert, heat exchanger
insert or other accessory not approved for use
with this fireplace.
20. Provide adequate clearances around air
openings.
UNPACKING
The following items are packed inside the firebox.
Remove before positioning firebox into framing.
• Transition Collar - For vent connection
• Ceramic Log Pack - Shrink-wrapped on card-
board
• Three (3) plastic bags containing lava rock, pan
and ember materials
• Rear Log - Remove the two plastic quick ties
from around the burner and grate
• Grate Stand - Lift off of burner pan
SAFETY INFORMATION
Continued
Check all items for any shipping damage. If dam-
aged, promptly inform dealer or distributor where
you bought the product.
Safely retain these items for later installation.
INTRODUCTION
Models M36(P)(B,H), VM36(P)(B,H),
M42(P)(B,H) and VM42(P)(B,H) are vented gas
fireplaces that use a millivolt gas control valve with
a millivolt ignition system. A 6" B-Type venting
system and a listed type vent cap are not supplied
but are required for proper operation. See venting
instructions on pages 9 and 10.
WARNING: This gas appli-
ance must not be connected to
a chimney flue servicing a solid
fuel burning appliance.
Models M36(B,H), VM36(B,H), M42(B,H) and
VM42(B,H) are factory equipped for use with
natural gas and must be converted when intended
for use with propane/LP gas. A respective model
PCBM-36 or PCBM-42 conversion kit may be
purchased for simple conversion to propane/LP
gas. See Accessories, page 31.
BEFORE YOU BEGIN
Before beginning the installation of your appli-
ance, read these instructions through completely.
This DESA appliance and its approved compo-
nents are safe when installed according to this
installation manual and are operated as recom-
mended by DESA. Unless you use DESA approved
components tested for this appliance, YOU MAY
CAUSE A FIRE HAZARD!
The DESA warranty will be voided by and DESA dis-
claims any responsibility for the following actions :
A) Modification of the appliance or any of the
components.
B) Use of any component part not approved by
DESA in combination with this appliance.
C) Installation and/or operation in a manner other
than instructed in this manual.
D) The burning of anything other than the type of
gas approved for use in this gas appliance.
The installation must conform with local codes or, in
the absence of local codes, with the current National
Fuel Gas Code, ANSI Z223.1/NFPA 54 or with the
current CAN/CGA B149 Installation Codes.
This appliance complies with ANSI Z21.50-2000
and CSA 2.22-2000 as Vented Gas Fireplaces and
is listed and tested by the Canadian Standards
Association to the above test standards.

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108795-01N 5
WARNING: Installation of
this appliance should be done
by a qualified service person
well trained in the installation
of such appliances. You will
also need a building permit from
your local Building and Safety
Commissioner before installing
this appliance; otherwise your
insurance co. may not cover this
appliance.
NOTICE: This appliance is not
intended to be used as a primary
source of heat.
CAUTION: Do not connect
appliance before pressure test-
ing gas piping. Damage to gas
valve may result and an unsafe
condition may be caused.
The appliance and itʼs individual shutoff valve
must be disconnected from the gas supply piping
system during any pressure testing of that system at
test pressures in excess of 1/2 psig (3.5 kPa).
The appliance must be isolated from the gas sup-
ply piping system by closing its individual manual
shutoff valve during any pressure testing of the gas
supply piping system at test pressures equal to or
less than 1/2 psig (3.5 kPa).
For the purpose of input adjustment two pressure
taps (for IN and OUT pressures) are provided on
the gas control valve for test gauge connections
to the appliance.
INTRODUCTION
Continued
Figure 1 - Possible Locations for
Installing Appliance
INTERNAL WALL
INSTALLATION
CORNER
INSTALLATION
FULL
PROJECTION
INSTALLATION
FLUSH
INSTALLATION
SELECTING LOCATION
To determine the safest and most efficient location
for your appliance, you must take into consider-
ation the following guidelines:
1. The location must allow for proper clearances
(see Clearances, page 7).
2. Consider a location where heat output would
not be affected by drafts, air conditioning
ducts, windows or doors.
3. A location that avoids the cutting of joists
or roof rafters will make installation easier.
Figure 1 shows a plan view of a few common
locations.
Flush installations are recommended where
living space is limited or at a premium and since
the space required to enclose the appliance would
be located beyond an outside wall, this would also
reduce the cutting of joists, roof rafters and such.
Check local codes for any restrictions.
Projected installations can extend any distance
into the room. A projection may be ideal for a new
addition on an existing, finished wall.
Corner installations make use of space that may
not normally be used and provides a wider and
more efficient range for radiant heat transference.
Internal wall installations provide a discreet
option for room separation and can also be ideal
as an addition to an existing wall.

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Model 36 Model 42 Model 36 Model 42 Model 36 Model 42
A 29" 36" I 40 1/4" 44 1/4" Q 13 7/8" 14"
B 5/8" 5/8" J 21" 24" R 10 1/2" 12 1/2"
C 41" 48" K 8" 9" S 2 1/2" 2 1/2"
D 12" 14" L 34 3/4" 42" T 8 1/8" 8 1/8"
E 21 1/4" 23" M 42" 49" U 11" 12 3/4"
F 22 1/4" (24" w/o Brick) 29 1/4" (31" w/o Brick) N 36" 40" V 7" 7"
G 32 5/8" (34" w/o Brick) 39 1/2" (41 1/4" w/o Brick) O 37" 41" W 2 1/4" 2 1/4"
H 15 3/4" (16 3/4" w/o Brick) 17 3/4" (18 3/4" w/o Brick) P 8 5/8" 10 1/2" X 5" 4 1/2"
PRODUCT SPECIFICATIONS
GAS RATING - NATURAL
M36(B,H), VM36(B,H) M42(B,H), VM42(B,H)
Max. Input Rating: 40,000 Btu/Hr 45,000 Btu/Hr
Manifold Pressure: 3.5 in. WC (.87 kPa) 3.5 in. WC (.87 kPa)
Minimum Supply Pressure: 4.5 in. WC (1.12 kPa) 4.5 in. WC (1.12 kPa)
Maximum Supply Pressure: 10.5 in. WC (2.66 kPa) 10.5 in. WC (2.66 kPa)
Orifice Size: # 30 # 29
GAS RATING - PROPANE/LP
M36P(B,H), VM36P(B,H) M42P(B,H), VM42P(B,H)
Max. Input Rating: 40,000 Btu/Hr 45,000 Btu/Hr
Manifold Pressure: 10 in. WC (2.49 kPa) 10 in. WC (2.49 kPa)
Minimum Supply Pressure: 11 in. WC (2.74 kPa) 11 in. WC (2.74 kPa)
Maximum Supply Pressure: 13 in. WC (3.23 kPa) 13 in. WC (3.23 kPa)
Orifice Size: # 52 # 50
S
T
P
Q
R
X
Outside Air
Kit Location
(Optional)
K
7"
J
I
M
L
V
13.5"
1.5"
Glass Door
(Optional)
W
O
N
Alternate
Gas Supply
Inlet
7"
G
H
F
A
Stand Off
Collar
For Use With
6"Ø Type B-1
Vent Pipe Only
B
E
D
C
DIMENSIONS
HEARTH AREA
7"
Figure 2 - Appliance Dimensions

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108795-01N 7
PRE-INSTALLATION
PREPARATION
CLEARANCES
Minimum clearances to combustibles are:
• Back and Sides of Outer Surround . . . 0" min.
• Drywall to Sides of Front Face
(Nailing Flanges) . . . . . . . . . . . . . . 0" min.
• “B” Vent Surfaces . . . . . . . . . . . . . . . . 1" min.
• Ceiling to Opening . . . . . . . . . . . . . . 42" min.
• Floor . . . . . . . . . . . . . . . . . . . . . . . . . . 0" min.
• Perpendicular Wall . . . . . . . . . . .See Figure 6
CAUTION: Do not block
required air spaces with insu-
lation or any other material. Do
not obstruct effective opening
of appliance with any type of
facing material.
Figure 3 - Minimum Clearances
(Top View)
0"
0" Clearance
Nailing
Flange
Front Face
Left Side
Surround
Back
Drywall
2 x 4 Stud
Figure 4 - Minimum Clearances
(Front View)
**
**
42" (1067mm)
Min. Clearance
from Opening to
Ceiling 0" Clearance
Ceiling
1" (25mm) Min.
Clearance to
"B" Vent's Outer Pipe
Maintain 2" (51mm) Min.
Clearance to the Transition
Pipe as Measured at the
Outer Vent Collar
Required Air
Spaces are
Indicated with
an "
*
". Do Not
Pack with
Insulation or Any
Other Material
DO NOT BLOCK
OR OBSTRUCT
OPENINGS
0" Clearance to
Combustible or
Noncombustible
Flooring
MANTEL CLEARANCES AND WALL
DETAILS
A combustible mantle shelf maybe installed a
maximum 12" (229 mm) from the wall. Figures
5 and 6 show the minimum allowable distances
from various combustible mantle components
in relation to the fireplace opening.
Spacer
3" (76mm)
1 1/2"
(38mm) Max.
B
6" (152mm)
A
12"
(229mm)
Combustible
Materials
Header
Figure 5 - Mantel Clearances - Side View
(Cross Section)
M36(B,H),
M36P(B,H)
VM36(B,H),
VM36P(B,H)
M42(B,H),
M42P(B,H)
VM42(B,H),
VM42P(B,H)
A 14" (356 mm) 15" (381 mm)
B 8" (203 mm) 9" (229 mm)
1 1/2" (38 mm)
Max. 3" (76 mm)
Max.
6" (152 mm)
Max.
A
B
Outer Surround
Combustible
Material May
Be Used
TOP VIEW
SAFE
ZONE
Perpendicular
Wall
Figure 6 - Side Clearances - Top View
(Cross Section)
M36(B,H),
M36P(B,H)
VM36(B,H),
VM36P(B,H)
M42(B,H),
M42P(B,H)
VM42(B,H),
VM42P(B,H)
A 9" (229 mm) 6" (152 mm)
B 12" (305 mm) 9" (229 mm)

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PRE-INSTALLATION
PREPARATION
Continued
FRAMING
1. Frame appliance enclosure as illustrated in
Figures 7 and 8.
Note: If a wall covering is used to line the
enclosure, then all measurements must be
from the surface of the covering.
2. Place the appliance into the framing and
secure it.
Note: If appliance is to be raised above floor
level, a platform must be built to support the
appliance.
3. Install the supply line to the appliance using a
1/2" NPT black iron gas line terminating 2 5/16"
above the bottom of the appliance. The gas line
must be installed through the lower left side ac-
cess point or alternate access hole in the bottom
of the appliance (see Figure 19, page 13).
4. Repack insulation around the gas line to cover
any remaining openings in the conduit sleeve.
Prepare the incoming gas line with teflon tape
or pipe joint compound and hook-up incoming
gas line to the flexible gas line.
Note: If 1/2" NPT black iron pipe does not
mate with fitting at the end of flexible gas line,
remove fitting and replace with a 37 degree
flare 3/4"-12, 1/2" NPT (female) fitting.
WARNING: When finishing
appliance, do not overlap com-
bustible material onto the black
front face. Brick, tile or other non-
combustible materials may be
applied to the face provided that
any gap is between the material
used and the face is caulked with
a noncombustible caulking.
Figure 7 - Rough Opening for Installing
in Wall
B
C
A
M36(B,H),
M36P(B,H)
VM36(B,H),
VM36P(B,H)
M42(B,H),
M42P(B,H)
VM42(B,H),
VM42P(B,H)
A 40 3/8" (1020 mm) 44 3/8" (1121 mm)
B 21 3/8" (543 mm) 23 1/8" (587 mm)
C 41 1/4" (1048 mm) 48 1/4" (1226 mm)
Figure 8 - Corner Installation Guidelines
A
B
C
D
M36(B,H),
M36P(B,H)
VM36(B,H),
VM36P(B,H)
M42(B,H),
M42P(B,H)
VM42(B,H),
VM42P(B,H)
A 24 1/2"
(622.3 mm)
27 9/16"
(700.1 mm)
B 73 7/8"
(1876.4 mm)
83 7/8"
(2130.4 mm)
C 52 3/16"
(1326 mm)
59 5/16"
(1506.6 mm)
D 17 1/4"
(438.2 mm)
19 1/2"
(495.3 mm)
These Dimensions Allow for a 3/4"
Clearance at Sides and Back of Fireplace.
However, 0" Clearance is Permitted
3/4" Clearance Not Required at
Nailing Flanges

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108795-01N 9
INSTALLING TRANSITION PIPE AND
STARTER COLLAR
The transition pipe and starter collar shown in
Figure 9 are supplied with the fireplace, unattached
and ready for installation. Remove the starter collar
and set aside. Slide the transition pipe over the vent
collar and attach with a minimum of three screws.
Replace the starter collar over the transition pipe
and attach using four screws located on the leg
stands (five used on the model M42). To install
B-vent piping, slide the first piece of B-vent over
the transition pipe and attach with either a mini-
mum of two screws or other means approved by
the vent manufacturer.
Figure 9 - Installing Transition Pipe and
Starter Collar
B-Vent Piping
Transition Pipe
Starter Collar
Vent Collar
PRE-INSTALLATION
PREPARATION
Continued
VENTING INSTALLATION
A B-type venting system must be connected to the
appliance for venting to the outside of the building.
The following section is provided as a guide to a
standard B-type vent installation.
Standing codes requirements concerning B-type
vent installations may vary within your state,
province or local codes jurisdiction. Therefore,
it is recommended that you check with your
local building codes for specific requirements
or in absence of local codes, follow Section 7.0
of the current National Fuel Gas Code ANSI
Z223.1/NFPA 54 and in Canada with CAN/CGA
B149 for Category I systems using double wall
B-1 vent pipe.
This gas appliance must be vented to the outdoors
only and may not be terminated into an attic space
or into a chimney flue servicing a solid-fuel burn-
ing appliance.
This appliance may be vented through a manufac-
tured chimney system or a masonry chimney using
a B-vent adapter or a chimney liner system if all
are listed, inspected and approved by local codes
and/or building authorities.
The examples shown in Figure 10, page 10 are
typical of most B-vent installations and codes
practices.
Example 1: Shows the minimum allowable sys-
tem height and lateral offset for a 60° degree or
greater inclination. Code specifies that offsets at
60° degrees or greater are considered horizontal
and must follow the 75% percent rule for lateral
to total vertical system height. Codes also allows
only one offset in the total system when at 60°
degrees or greater. The total vertical height in this
example represents the minimum height of 8 feet
and therefore the allowable lateral is 6 feet when
the 75% percent rule applies. If the lateral length
must exceed 75% then the system must be sized in
accordance with the Category I venting tables.
Example 2: Shows a multiple offset each at 45°
degrees of inclination. Multiple offsets are permit-
ted if they do not exceed 45° degrees of inclination.
The total lengths of the two offsets are not required
to meet the 75% percent allowable rule.
Example 3: Shows a single offset at 45° degrees
of inclination and therefore the lateral length at
10 feet of offset does not have to meet the 75%
percent rule.
In each case the offsets must be supported and
firestops must be positioned wherever the vent
must pass through a sub-floor, ceiling joist or
an attic overhang. The vent pipe must terminate
vertically into a listed type vent cap and extend a
sufficient height through an approved roof flash-
ing, roof jack or a roof thimble. At all points the
listed clearances must be maintained.
Vent terminations must be located in accordance
with height and proximity rules of NFPA No. 54 or
CAN/CGA B149. These rules apply to vents at 12
in. diameter or less and require a minimum height
in accordance with the roof pitch and a minimum
of 8 ft. distance from a vertical wall or obstruction
(see Figure 11, page 10).
If venting horizontally through a side wall be-
comes necessary, a listed thimble approved for use
with B-type vent must be used. Check with your
local codes before venting through a side wall.
Some codes areas allow the use of existing B-type
vent systems if the system is at or above the recom-
mended diameter of the flue; in this case 6".
The flue connection must be made using listed

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Maintain
Listed
Clearance
12' Min.
12' Min.
45
45
6'
8'
12' Min.
60 45
Position
Firestop
Position
Firestop
Position
Firestop
Listed
Vent Cap
Listed
Vent Cap
Listed
Vent Cap
Maintain
Listed
Clearance
Maintain
Listed
Clearance
Maintain
Listed
Clearance
Maintain
Listed
Clearance
Maintain
Listed
Clearance
Support Each
Lateral At
Least Every
Six (6) Feet
Maintain
Listed
Clearance
10'
EXAMPLE 3EXAMPLE 2EXAMPLE 1
Figure 10 - Typical B-Vent Configuration
VENTING INSTALLATION
Continued
B-type connectors and the existing system must be
code inspected for damage and proper installation.
It is not recommended that this appliance be com-
mon vented with an existing gas burning appliance.
However, if it becomes necessary to common vent
this appliance, the venting system must be sized
and configured in accordance with the common
venting guides Appendix G of the current National
Fuel Gas Code ANSI Z223.1/NFPA 54 and in
Canada with CAN/CGA B149.
Note: Before connecting this appliance to an
existing vent system or a common venting sys-
tem consult with your local architect, planner or
building official.
WARNING: This appliance
must be properly connected
to a system and must not be
connected to a chimney flue
servicing a separate solid fuel
burning appliance.
Lowest
Discharge
Opening
Listed
Vent Cap
8 Ft. Min.
Roof Pitch x/12
Listed Clearance
12
x
Listed Gas
Vent
H (Min)
Height
From Roof
Roof Pitch
H (Min.)
Ft. m
Flat to 6/12 1.0 ax0.30
6/12 to 7/12 1.25 0.38
Over 7/12 to 8/12 1.5 0.46
Over 8/12 to 9/12 2.0 0.61
Over 9/12 to 10/12 2.5 0.76
Over 10/12 to 11/12 3.25 0.99
Over 11/12 to 12/12 4.0 1.22
Over 12/12 to 14/12 5.0 1.52
Over 14/12 to 16/12 6.0 1.83
Over 16/12 to 18/12 7.0 2.13
Over 18/12 to 20/12 7.5 2.27
Over 20/12 to 21/12 8.0 2.44
Figure 11 - B-Vent Terminations

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108795-01N 11
CHECKING FOR PROPER VENTING
After completing and checking the electrical,
gas and vent connections, follow the lighting
instructions and allow the main burner to run for
approximately 5 minutes. Hold a lighted match or
cigarette near the top edge of the fireplace opening
and play it along the entire length of the opening
(see Figure 12). Proper venting should tend to draw
the flame or smoke into the appliance. Improper
venting or escaping of spillage of burned gas, is
indicated when the match flickers or goes out.
Smoke from a cigarette will also tend to disperse
away from the appliance.
If the appliance is found to be improperly venting,
shut it off and notify your installer or a qualified
service agency to inspect the venting system.
NOTICE: This appliance is
equipped with a vent safety shutoff
switch which will shut down the
appliance in the case of a venting
problem. Do not bypass the vent
safety switch. If the appliance
should shut down, contact a quali-
fied installer, service agency or
your gas supplier to have the vent
inspected before operating.
VENTING INSTALLATION
Continued
Check this area along
the entire top edge of
the fireplace opening.
Smoke or flame should
be drawn into the
appliance opening.
Figure 12 - Checking for Spillage
INSTALLATION
WALL SWITCH INSTALLATION
The installation of a wall switch allows you to
activate the gas control valve without the normal
household electricity since the valve operates on
millivolt current supplied by the heat generated by
the thermopile. To install the wall switch:
1. Remove the front refractory access panel by
lifting up and angling out of the firebox open-
ing (see Figure 13).
2. Use wire and connectors provided. Attach red
wire to terminal marked TH/TP on control
valve. Attach white wire to blade connector on
open end of safety circuit wiring (see Wiring
Diagram, page 22).
Note: If any of the original wire from the unit
control must be replaced, use the same type or a
higher rated wire (25 ft. maximum length).
WARNING: Do not wire re-
mote wall switch to main power
supply (Standard 120v house-
hold current).
3. Locate wall switch in a convenient location.
4. After wire connections are complete, replace
refractory access panel.
Figure 13 - Removing Front Refractory
Access Panel

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OPTIONAL WIRELESS HAND-HELD
REMOTE CONTROL INSTALLATION
Note: If using optional wireless hand-held remote
control, the wall switch is no longer operational.
Installing Receiver
1. Remove the front refractory access panel by
lifting up and angling out of the firebox opening
(see Figure 13, page 11) to expose controls.
2. Disconnect wall switch wires from TH
and TH/TP terminals on control valve (see
Figure 14).
3. Install remote receiver unit onto mounting
bracket using the two plastic mounting clips
(see Figure 15).
4. Connect wires to control circuit. Connect
white wire to terminal marked TH/TP on
control valve. Connect red wire to male blade
connector provided at open end of safety cir-
cuit wiring (see Wiring Diagram, page 22).
5. Locate the battery clip mounted on the back
of the receiver (see Figure 16).
6. Slide 9-volt battery (not included) through the
clip. Note: Only use alkaline battery.
7. Attach the terminal wires to the battery (see
Figure 16).
8. Replace refractory brick access panel.
Note: If any of the original wire as supplied must
be replaced, use 18 AWG TYPE CL2 (UL) 105 C
(25 ft. length MAXIMUM) or equivalent.
Conduit Sleeve
To Safety Circuit Route Millivolt
Through Gas Line
To Thermopile
Wires (Supplied)
Wall Switch
(Supplied)
(Back View)
IN
TH
TP
THTP
IN OUT
O
F
F
P
I
L
O
T
O
N
INSTALLATION
Continued
Figure 14 - Wall Switch Wiring Diagram
Figure 15 - Installing Remote Receiver
(Shown from Rear of Mounting Bracket)
Receiver
Mounting Bracket
Plastic
Mounting
Clips
Figure 16 - Installing Battery in Receiver
Battery
Clip
9-Volt Battery
Receiver
Terminal
Wires

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108795-01N 13
GAS LINE HOOK-UP
WARNING: Gas line hookup
should be done by your gas
supplier or a qualified service
person.
WARNING: Before you pro-
ceed, make sure your gas supply
is OFF.
A manual shutoff valve has been included in the
applianceʼs gas supply system. You may consider
installing an extra gas shutoff valve outside the
applianceʼs enclosure (check with local codes)
where it can be accessed more conveniently with
a key through a wall as shown in Figure 18.
In conformance with local codes, route a 1/2" NPT
gas line to the appliance through hole in left side of
firebox or sub-floor as shown in Figure 19.
CAUTION: Do not kink flex-
ible gas line.
Installing 9-Volt Battery in Hand-Held
Remote Control Unit
1. Remove battery cover on back of remote
control unit.
2. Attach terminal wires to the battery (not in-
cluded). Place battery into the battery housing.
Note: Only use alkaline battery.
3. Replace battery cover onto remote control
unit.
Figure 17 - Installing Battery in Hand-
Held Remote Control Unit
Battery Cover
9-Volt
Battery
Terminal
Wires
Remote
Control Unit
Battery
Housing
INSTALLATION
Continued
DESA recommends that a black iron gas line be
routed from the gas source, through a sediment
trap (shown in Figure 20) and into the appliance.
Once connected through the appliance, a flexible
gas line may be used for ease of installation to gas
control valve (see Figure 21, page 14).
Before connecting the black iron gas line to the
inside of the appliance a sediment trap must be
included outside the appliance between the gas
line and the gas shutoff valve. It must extend
down three (3) inches beyond the center of the
pipe. Prepare incoming black iron gas line with
teflon tape or pipe joint compound (Check with
local building codes).
Figure 18 - Manual Shutoff Valve
Installation
Typical Exterior Wall Gas
Shutoff Installation
Key
Extension
Shutoff
Valve
Figure 19 - Routing Incoming Gas Line
A
1/2" NPT Incoming
Black Iron Gas Line
7"
7"
Alternate Gas Supply
Through Sub-Floor
M36(B,H),
M36P(B,H
VM36(B,H),
VM36P(B,H)
M42(B,H),
M42P(B,H)
VM42(B,H),
VM42P(B,H)
A 8 5/8" (219 mm) 10 1/2" (267 mm)
Incoming
1/2" Gas Line
Permitted by
Local Codes
Sediment
Trap (Not
Supplied)
Figure 20 - Sediment Trap
3" Min.
(76mm)

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P
I
L
O
T
ON
OFF
IN OUT
Figure 21 - Connecting Flexible Gas Line to Millivolt Valve
Gas Shutoff
Valve
Flexible Gas Line
Do NOT Kink
1/2" NPT
Incoming
Gas Line
Note:
1) Wire Connections
Not Shown for Clarity
2) * 1/8" NPT Plugged
Tapping
Red Surface Indicates For
Propane/LP Use Only Pilot Adj
Inlet Pressure Tap
Outlet
Pressure Tap
CAUTION: Compounds used
on threaded joints of gas piping
shall be resistant to the action
of Liquefied Petroleum (LP or
propane) and should be applied
lightly to ensure excess sealant
does not enter the gas line.
WARNING: All gas piping
and connections must be tested
for leaks after the installation is
completed.
After ensuring that the gas valve
is on, apply a commercial leak
detection solution to all con-
nections and joints. If bubbles
appear, leaks can be detected
and corrected.
Do not use an open flame for leak
testing and do not operate any
appliance if a leak is detected.
Complete your gas installation by connecting
incoming gas line with flexible gas line. Secure
tightly with wrench but DO NOT OVER-
TIGHTEN.
INSTALLATION
Continued
EMBER AND PAN MATERIAL
PLACEMENT
1. Open the bag(s) of vermiculite and fill the
entire burner pan until the burner tube is
completely covered (see Figure 22).
2. Smooth the pan material just even with edges
of the burner pan.
3. Remove the ember material from the bag and
flatten small amounts into quarter size pieces
and lay on top of the surface of the pan mate-
rial (see Figure 23).
4. Place just enough to cover the entire surface
and leave about a 1/2 inch gap under the
lower grate members to allow air to flow (see
Figure 24, page 15).
Figure 22 - Fill Entire Burner Pan with
Vermiculite
Figure 23 - Ember Material on Surface of
Pan Material (Vermiculite)
Vermiculite
(Pan Material) Burner Pan
Grate
Ember Material
Burner
Pan
Vermiculite (Pan Material)
Grate

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108795-01N 15
0.5"
0.5"
Figure 24 - Pan and Ember Material
Clearances
Grate
Burner Pan
Pan and Ember
Material
INSTALLATION
Continued
LOG PLACEMENT FOR M36, M36P,
VM36 AND VM36P MODELS
1. Place small front right log (log 1) on right front
of grate as shown in Figure 25.
2. Place large back log (log 2) onto grate mak-
ing sure notches rest over grate as shown
in Figure 25.
3. Place log 3 into notch on log 2, resting the
front end on top of log 1 (see Figure 26).
4. Place the upper end of log 4 into the notch on
log 2 as shown in Figure 26. Rest the lower
end of log 4 onto the middle grate finger as
shown in Figure 27.
5. Place the upper end of log 5 into notch on the
left of log 2 (see Figure 27). Rest the lower end
of log 5 on the grate as shown in Figure 28.
6. Insert the lower end of log 6 between the first two
grate fingers as shown in Figure 28 and position
the upper end of log 6 into the notched area on
the front of log 2 as shown in Figure 28.
As an option to enhance the look of the hearth,
you may place the lava rock provided around the
front and sides of the burner.
Figure 25 - Installing Logs 1 and 2
Log 1
Log 2
Notch
Figure 26 - Installing Logs 3 and 4
Log 3
Log 4
Log 2
Log 1
Notches
NOTICE: Do not put lava rock
inside the burner pan or around
the air mixer fitting. Placing lava
rock inside the burner pan or
blocking the openings of the pro-
pane/LP air-mixer could cause
performance problems.
Figure 27 - Installing Logs 5 and 6
Log 5
Log 6
Log 4
Notch
Notch
Figure 28 - Logs Installed for M36, M36P,
VM36 and VM36P Models

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INSTALLATION
Continued
LOG PLACEMENT FOR M42, M42P,
VM42 AND VM42P MODELS
1. Place large back log (log 1) onto grate making
sure notches rest over grate (see Figure 29).
2. Insert lower end of log 2A between the first two
grate fingers and position the upper end into
the notch on the front of log 1. See Figure 29.
Place log 2B on the front right side of grate as
shown in Figure 29.
3. Place log 3 into notch on top left of log 1, rest-
ing the lower end on the left two grate fingers
(see Figure 30).
4. Place the upper end of log 4 into the notch on
log 1 as shown in Figure 30. Rest the lower
end of log 4 on the middle grate finger as
shown in Figure 31.
5. Place the upper end of log 5 into the notch on
the top inner right of log 1 (see Figure 31).
Rest the lower end of log 5 on the middle grate
finger as shown in Figure 32.
6. Place log 6 into the notch on the top right of log
1 (see Figure 31). Rest the lower end of log 6
on top of log 2B (see Figure 32).
As an option to enhance the look of the hearth,
you may place the lava rock provided around the
front and sides of the burner pan.
NOTICE: Do not put lava rock
inside the burner pan or around
the air mixer fitting. Placing lava
rock inside the burner pan or
blocking the openings of the
propane/LP air-mixer could cause
performance problems.
Figure 29 - Installing Logs 1, 2A and 2B
Log 2A
Log 2B
Log 1
Notch
Figure 30 - Installing Logs 3 and 4
Log 4
Log 3
Log 1
Notches
Figure 31 - Installing Logs 5 and 6
Figure 32 - Logs Installed for M42, M42P,
VM42 and VM42P Models
Log 6
Log 5
Notch
Log 1
Log 2B

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108795-01N 17
INSTALLATION
Continued
COMBUSTION AIR KIT MODEL AK4
(OPTIONAL)
The outside air kit may be installed on the left side
of the fireplace only. The vent can be installed
through any outside wall a minimum of three feet
below fireplace termination cap. The handle to
operate the damper door for the outside air inlet
will be located inside the left “screen pocket” of
the firebox (see Figure 33). Pull the handle to open
or push to close.
CAUTION: Air inlet ducts are
not to terminate in attic space.
Figure 33 - Air Kit Handle Location
Air Kit
Handle
Screen
Pocket
APPLIANCE ENCLOSURE
Before finishing the enclosure around the appli-
ance, inspect all joints around the outer surround.
Any gaps between the nailing flanges and the
framing should be sealed with noncombustible
insulation or caulking.
If the appliance is mounted on a raised platform,
it must be a continuous surface and not on blocks
without a solid surface. This will prevent the entry
of cold air by means of conduction through the
total bottom of the appliance (see Figure 34).
Side
Framing
Side
Framing
Caulk Here Pack Insulation
Figure 34 - Sealing Between Appliance
and Framing
INSTALLING OPTIONAL GLASS
DOOR ACCESSORY
CAUTION: Use only glass
doors certified for use with this
appliance.
Note: Glass door may be heavy for some individu-
als. If this is the case, please request help from
someone else.
The M36, VM36, M42 and VM42 B-vent fire-
places are approved for use with optional bi-fold
glass doors (see Accessories, page 31). The glass
panels may be ordered and installed anytime after
the fireplace installation is complete.
Follow these steps to install left and right panels:
1. With the handle at the bottom, completely fold
the panel on its hinges.
2. With the handle facing the center of the firebox
opening, insert the lower pivot pin on the glass
door panel into the hole in pivot plate on the
bottom edge of the fireplace opening (see
Figure 35).
3. Keeping the folded door tilted, slide the upper
two pins into the guide track found under the
upper facial edge of the firebox opening.
4. Tilt the glass assembly fully vertical until the
outer pivot pin snaps into the mounting hole
in the upper spring clip (see Figure 35).
5. Once the top and bottom pins are secured,
unfold the door into the closed position.
Figure 35 - Installing Optional Glass
Door
Spring Clip
Insert Pin Into
Spring Clip
Insert Bottom Pivot Pin Into
Pivot Plate and Swing Door
Into Vertical Position
Pivot Plate
Slide Top
Pin Into
Door Track

www.desatech.com 108795-01N18
6. Repeat the process for the opposite door
assembly.
7. To adjust the doors, slide them partially open.
Using a screwdriver, loosen the hold-down
screws in the spring clip (see Figure 36) and
pivot plate.
8. Close both doors until evenly joined at the
middle and note the gap at the outer edges of
the face.
9. Reopen one door at a time and retighten the
upper and lower hold-down screws.
10. Repeat the process until both doors are evenly
joined, spaced and working freely.
CAUTION: The glass pan-
els become very hot while the
appliance is operating. Do not
attempt to adjust or clean the
glass doors until the appliance
has fully cooled.
The doors may be removed for replacement or
cleaning as follows:
1. Partially open the door and press up on the
upper spring clip with a screw driver until the
outer top pivot pin is free of the clip.
2. Fully fold the frame assembly and slide the
upper edge towards the center of the firebox
opening until the guide pins are free of the
frame rail (see Figure 37).
CAUTION: Always operate
the appliance with the doors ei-
ther fully opened or fully closed.
Operating the appliance with
the doors partially open can re-
sult in improper venting of flue
products.
INSTALLATION
Continued
Figure 36 - Adjusting Glass Doors
Spring
Clip
Hold-Down
Screw
Side
Front
Face
Partially
Opened
Door
Figure 37 - Removing Glass Doors
Spring Clip
Depress
Spring Clip
to Release
Pivot Pin
Remove Bottom Pin
From Pivot Plate While
Sliding Door Out of the
Upper Track
Pivot Plate
Fold Bi-Fold
Door After
Releasing
Spring Clip
and Slide
Door Out of
Upper Track
OPENING VENT DAMPER
Vent damper must be locked in the full open posi-
tion before operating the fireplace. If vent damper
is not open, fireplace will not light.
CLOSEOPEN
VENT DAMPER MUST BE LOCKED
IN THE FULL OPEN POSITION
TO OPERATE THE APPLIANCE
Figure 38 - Opening Vent Damper

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108795-01N 19
OPERATING FIREPLACE
FOR YOUR SAFETY
READ BEFORE LIGHTING
WARNING: If you do not fol-
low these instructions exactly,
a fire or explosion may result
causing property damage, per-
sonal injury or loss of life.
A. This appliance has a pilot which must be
lighted by hand. When lighting the pilot,
follow these instructions exactly.
B. BEFORE LIGHTING smell all around the
appliance area for gas. Be sure to smell next
to the floor because some gas is heavier than
air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electric switch; do not
use any phone in your building.
• Immediately call your gas supplier
from a neighborʼs phone. Follow the
gas supplierʼs instructions.
• If you cannot reach your gas supplier,
call the fire department.
C. Use only your hand to push in or turn the
gas control knob. Never use tools. If the
knob will not push in or turn by hand, donʼt
try to repair it, call a qualified service tech-
nician or gas supplier. Force or attempted
repair may result in a fire or explosion.
D. Do not use this appliance if any part has
been under water. Immediately call a
qualified service technician to inspect the
appliance and to replace any part of the
control system and any gas control which
has been under water.
LIGHTING
INSTRUCTIONS
NOTICE: During initial operation
of new heater, burning logs will
give off a paper-burning smell.
Orange flame will also be pres-
ent. Open damper or window to
vent smell. This will only last a
few hours.
1. STOP! Read the safety information,
column 1.
2. Turn wall switch to the OFF position.
3. Turn off all electric power to the appliance.
4. Fully open glass doors if installed.
5. Remove front refractory brick access panel.
6. Turn gas control knob clockwise
to the OFF position (see Figure 39).
7. Wait five (5) minutes to clear out any gas.
Then smell for gas, including near the floor.
If you smell gas, STOP! Follow “B” in the
safety information above. If you donʼt smell
gas, go to the next step.
8. Turn control knob counterclockwise
to the PILOT position.
9. Push in the knob all the way and hold in.
Immediately light the pilot manually. Con-
tinue to hold the control knob in for about
(1) minute after the pilot is lit. Release knob
and it will pop back up. Pilot should remain
lit. If it goes out, repeat steps 5 through 9.
• If knob does not pop up when released,
stop and immediately call your service
technician or gas supplier.
• If the pilot will not stay lit after sev-
eral tries, turn the gas control knob to
“OFF” and call your service technician
or gas supplier.
10. Turn gas control knob counterclockwise
to “ON”. Knob can be turned to
“ON” only if the control knob is popped out.
11. Replace front refractory brick access panel.
12. Fully close glass doors if installed.
13. Turn on all electric power to the appliance.
P
I
L
O
T
ON
OFF
IN OUT
IN
Figure 39 - Control Knob in the PILOT
position
Position
Indicator
Gas Control
Knob
Pilot Adjustment
Screw

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TO TURN OFF GAS
TO APPLIANCE
1. Turn off the wall switch.
2. Turn off all electric power to the appliance
if service is to be performed.
3. Fully open glass doors if installed.
4. Remove front hearth brick and control
access panel.
5. Turn gas control knob clockwise
to “OFF”. Do not force.
6. Replace front refractory brick access
panel.
7. Fully close glass doors if installed.
OPERATING FIREPLACE
Continued
Figure 40 - Pilot
Thermopile
Pilot
Burner
Ignitor
Figure 41 - On/Off Hand-Held Remote
Control Unit HRC100
Control
Button
Indicator
Light
INSPECTING BURNERS
Check pilot flame pattern and burner flame pat-
terns often.
PILOT ASSEMBLY
The pilot assembly is factory preset for the proper
flame height. Alterations may have occurred dur-
ing shipping and handling. The pilot is located on
the back right hand side of the burner.
The height of the thermopile must be 3/8" to 1/2"
above the pilot flame. The flame from the pilot
burner must extend beyond the thermopile.
If your pilot assembly does not meet these re-
quirements:
• Turn the adjustment screw marked pilot
clockwise to decrease or counterclockwise to
increase the flame to proper size (see Figure
39, page 19). Do not remove the adjustment
screw.
• see Troubleshooting, page 19
OPTIONAL HAND-HELD
REMOTE OPERATION
Note: The receiver and hand-held remote
control kit must be purchased separately (see
Accessories, page 31). Follow installation in-
structions on page 10 of this manual.
1. After lighting, let pilot flame burn for
about one minute. Turn control knob to
ON position. Slide the selector switch to
the REMOTE position. Note: The burner
may light if hand-held remote was on when
selector switch was last turned off. You can
now turn the burner on and off with the
hand-held remote control unit.
IMPORTANT: Do not leave the selector
switch in the REMOTE or ON position
when the pilot is not lit. This will drain the
battery.
2. Press the control button on the hand-held
remote to turn the burner on. Press the
control button again to turn burner off (see
Figure 41).
3. To Lock press both buttons on remote
control until light stops flashing. Remote is
now locked. If the fire is on it will be turned
off automatically. In the locked state, the
light will not light up when any button is
pressed.
4. To Unlock press both buttons together on
remote control until light stops flashing.
The remote is now unlocked.