![background image](http://html1.mh-extra.com/html/desa/vs18ntb/vs18ntb_owners-operation-and-installation-manual_2485662010.webp)
10
104414
DESA INTERNATIONAL
UNVENTED NATURAL GAS LOG HEATER
INSTALLATION
Continued
INSTALLING HEATER BASE
ASSEMBLY
WARNING: You must secure
this heater to fireplace floor. If
not, heater will move when you
adjust controls. Moving heater
may cause a gas leak.
WARNING: If installing in a
sunken fireplace, special care
is needed. You must raise the
fireplace floor to allow access
to heater control panel. This will
insure adequate air flow and
guard against sooting. Raise
fireplace floor with noncombus-
tible material. Make sure mate-
rial is secure.
CAUTION: Do not pick up
heater base assembly by burners.
This could damage heater. Only
handle base assembly by grates.
IMPORTANT:
Make sure the heater burn-
ers are level. If heater is not level, heater will
not work properly. For thermostat models,
avoid damage to thermostat bulb. Avoid
nicks or sharp bends in thermostat bulb
wire. Keep thermostat bulb in mounting
bracket.
CAUTION: Do not remove the
metal data plates attached to the
heater base assembly. The data
plates contain important warranty
information.
INSTALLING DAMPER
CLAMP ACCESSORY FOR
VENTED OPERATION
Note:
When used as a vented heater, appli-
ance must be installed only in a solid-fuel
burning fireplace with a working flue and
constructed of noncombustible material.
If your heater is a manually controlled model,
you may use this heater as a vented product.
There are three reasons for operating your
heater in the vented mode.
1.
The fireplace does not meet the clear-
ance to combustibles requirements for
vent-free operation.
2.
State or local codes do not permit vent-
free operation.
3.
You prefer vented operation.
If reasons number 1 or 2 above apply to you,
you must permanently open chimney flue
damper. You must install the damper clamp
accessory (to order, see Accessories, page
28). This will insure vented operation (see
Figure 10). The damper clamp will keep
damper open. Installation instructions are
included with clamp accessory.
See chart below for minimum permanent
flue opening you must provide. Attach
damper clamp so the minimum permanent
flue opening will be maintained at all times.
Figure 10 - Attaching Damper Clamp
Damper
Damper Clamp
Damper
Clamp
Damper
Damper
Manufactured Fireplace
Masonry Fireplace
Chimney
Minimum Permanent
Height (ft.) Flue Opening (sq. ins.)
6' to 15'
39 sq. inches
15' to 30'
29 sq. inches
Area of Various Standard
Round Flues
Diameter (ins.)
Area (sq. ins.)
5"
20 sq. inches
6"
29 sq. inches
7"
39 sq. inches
8"
51 sq. inches
Installation Items Needed
• hardware package (provided with heater)
• approved flexible gas hose (not provided)
(if allowed by local codes)
• sealant (resistant to LP gas, not provided)
• electric drill with 3/16" masonry drill bit
1.
Apply pipe joint sealant lightly to male
threads of gas fitting (not provided).
Connect approved flexible gas hose to
gas regulator of heater (see Figure 11,
page 11).
IMPORTANT:
Hold gas regulator with
wrench when connecting flexible gas
hose.
2.
Locate mounting brackets, bolts, and
nuts in hardware package. Attach
mounting brackets to heater base (see
Figure 12, page 11). Attach nuts finger
tight.
3.
Position heater base assembly in fire-
place.
4.
Mark screw locations through holes in
mounting brackets. If installing in a
brick-bottom fireplace, mark screw lo-
cations in mortar joint of bricks.
5.
Remove heater base from fireplace.
Remove mounting brackets from heater
base.
6.
Drill holes at marked locations using
3/16" drill bit.
7.
Attach mounting brackets to fireplace
floor using masonry screws (in hard-
ware package).