Empire Comfort Systems VFD26FM20N-2 Quick start guide

INSTALLATION INSTRUCTIONS
AND
OWNER'S MANUAL
UNVENTED
GAS FIREPLACE
MODELS
VFD26FM(2,3)0(N,W,C)-2
VFD26FP(2,3)0L-2
VFD26FP30L10-3
Vent-Free Gas Fireplaces
This appliance may be installed in an aftermar-
ket, permanently located, manufactured (mobile)
home, where not prohibited by local codes.
This appliance is only for use with the type of
gas indicated on the rating plate. This appliance
is not convertible for use with other gases.

(oxygen) from the room in which it is installed.
Provisions for adequate combustion and ventila-
tion air must be provided. Refer to page 9.
WATER VAPOR: A BY-PRODUCT OF UNVENTED
ROOM HEATERS
Water vapor is a by-product of gas combustion.
An unvented room heater produces approxi-
mately one (1) ounce (30ml) of water for every
1,000 BTU's (.3KW's) of gas input per hour. Refer
to page 8.
WARNING: If not installed, operated and main-
tained in accordance with the manufacturer's
instructions, this product could expose you to
substances in fuel or from fuel combustion which
can cause death or serious illness.
         -
mable vapors and liquids in the vicinity of
this or any other appliance.
— WHAT TO DO IF YOU SMELL GAS
  
  
use any phone in your building.
       
a neighbor’s phone. Follow the gas sup-
plier’s instructions.
  

— Installation and service must be performed

gas supplier.
WARNING: If the information in these instruc-
-
sion may result causing property damage,
personal injury or loss of life.
Installer: Leave this manual with the appli-
ance.
Consumer:Retain this manual for future refer-
ence.
EMPIRE
EMPIRE
Comfor t Systems
Page 1

27525-2-0411Page 2
SECTION PAGE
IMPORTANT SAFETY INFORMATION........................................................................... 3
SAFETY INFORMATION FOR USERS OF LP-GAS ...................................................... 4
INTRODUCTION ............................................................................................................. 5
BUILT-IN FIREPLACE INSTALLATION........................................................................... 6
FIREPLACE DIMENSIONS............................................................................................. 7
WATER VAPOR: A BY-PRODUCT OF UNVENTED ROOM HEATERS ......................... 8
SPECIFICATIONS........................................................................................................... 8
PROVISIONS FOR ADEQUATE COMBUSTION & VENTILATION AIR ....................9-10
GAS SUPPLY ................................................................................................................ 11
CLEARANCES .............................................................................................................. 12
COMBUSTIBLE MATERIAL .......................................................................................... 12
INSTALLATION OF FIREPLACE AND MANTEL......................................................13-14
LOG PLACEMENT ........................................................................................................ 15
PLACEMENT OF GLOWING EMBERS (ROCK WOOL) .............................................. 16
OPERATION INSTRUCTIONS/FLAME APPEARANCE ............................................... 16
10,000 BTU MILLIVOLT LIGHTING INSTRUCTIONS .................................................. 17
MILLIVOLT LIGHTING INSTRUCTIONS ...................................................................... 18
HYDRAULIC THERMOSTAT LIGHTING INSTRUCTIONS........................................... 19
PILOT FLAME CHARACTERISTICS .......................................................................20-21
MAIN BURNER AND THERMOSTAT OPERATION...................................................... 21
OUTER TRIM INSTRUCTIONS .................................................................................... 22
HOOD INSTRUCTIONS................................................................................................ 22
MILLIVOLT WIRING ...................................................................................................... 23
JUNCTION BOX WIRING INSTALLATION INSTRUCTIONS ....................................... 24
TROUBLESHOOTING .................................................................................................. 25
PARTS LIST .................................................................................................................. 26
PARTS VIEW................................................................................................................. 27
FBBX BLOWER KIT EXTENSION INSTALLATION INSTRUCTIONS .....................28-29
FBB4 OPTIONAL VARIABLE SPEED BLOWER .......................................................... 29
FPP26E OPTIONAL BRICK LINER KIT INSTALLATION INSTRUCTIONS.................. 30
MASTER PARTS DISTRIBUTOR LIST......................................................................... 31
HOW TO ORDER REPAIR PARTS ............................................................................... 31
TABLE OF CONTENTS

27525-2-0411 Page 3
Whenusedwithoutadequatecombustionandventilation air, heater
may give off CARBON MONOXIDE, an odorless, poisonous gas.
Do not install heater until all necessary provisions are
made for combustion and ventilation air. Consult the writ-
ten instructions provided with the heater for information
concerning combustion and ventilation air. In the absence
of instructions, refer to the National Fuel Gas Code, ANSI
Z223.1/NFPA 54, Air for Combustion and Ventilation, or ap-
plicable local codes.
This heater is equipped with a PILOT LIGHT SAFETY SYSTEM
designed to turn off the heater if not enough fresh air is avail-
able.
DO NOT TAMPER WITH PILOT LIGHT SAFETY SYSTEM!
If heater shuts off, do not relight until you provide fresh air.
If heater keeps shutting off, have it serviced. Keep burner and
control compartment clean.
CARBON MONOXIDE POISONING MAY LEAD TO DEATH.

headache, dizziness and/or nausea. If you have these signs, heater
may not be working properly. Get fresh air at once! Have heater
serviced.
Some people — pregnant women, persons with heart or lung dis-

altitudes — are more affected by carbon monoxide than others.
The pilot light safety system senses the depletion of oxygen at
its location. If this heater is installed in a structure having a high
vertical dimension, the possibility exists that the oxygen supply
at the higher levels will be less than that at the heater. In this type
of application, a fan to circulate the structure air will minimize this
effect. The use of this fan will also improve the comfort level in the
structure. When a fan is used to circulate air, it should be located

WARNING
DANGER: Indicates a hazardous situation which, if not avoided,
will result in death or serious injury.
WARNING: Indicates a hazardous situation which, if not avoid-
ed, could result in death or serious injury.
CAUTION: Indicates a hazardous situation which, if not avoided,
could result in minor or moderate injury.
NOTICE: Addresses practices not related to personal injury.
 
6,000 Btu per hour shall not be installed in a bathroom.
          
than 10,000 Btu per hour shall not be installed in a bedroom
or bathroom.
 

 
surface temperature and should stay away to avoid burns
or clothing ignition.
  
are in the same room with the appliance.
 
the appliance.
 Installation and repair should be done by a QUALIFIED
SERVICE PERSON. Thisapplianceshouldbeinspectedbefore
use and at least annually by a professional service person.
More frequent cleaning may be required due to excessive
lint from carpeting, bedding materials, etc. It is imperative
that control compartments, burners and circulating air
passageways of the appliance be kept clean.
 


any gas control which has been under water.
 
place. Do not close glass doors while operating heater.
 
operation.
      
components of this appliance are treated with certain oils,
        
harmful but may produce annoying smoke and smells as
they are burned off during initial operation of the appliance.
This is a normal temporary occurrence. A window should be
opened during the initial bake out period.
 
        
avoid potential problems with sooting. Sooting, resulting
from improper installation or operation, can settle on

installation.
 WARNING: Do not allow fans to blow directly into the

 WARNING: Do not use a blower insert, heat exchanger
insert or other accessory not approved for use with this
heater.
 
        

fresh air is not available.
        
materials, gasoline and other flammable vapors and
liquids.
THIS IS A HEATING APPLIANCE
IMPORTANT SAFETY INFORMATION

27525-2-0411Page 4
Some people cannot smell well. Some people cannot smell the

can smell the odorant in propane. Smoking can decrease your
ability to smell. Being around an odor for a time can affect your
sensitivity or ability to detect that odor. Sometimes other odors in
the area mask the gas odor. People may not smell the gas odor
or their minds are on something else. Thinking about smelling a
gas odor can make it easier to smell.
The odorant in LP-gas is colorless, and it can fade under some
circumstances. For example, if there is an underground leak, the
movement of the gas through soil can lter the odorant. Odorants
in LP-Gas also are subject to oxidation. This fading can occur if
there is rust inside the storage tank or in iron gas pipes.
by point with the members of your household. Someday
when there may not be a minute to lose, everyone's safety
will depend on knowing exactly what to do. If, after read-
ing the following information, you feel you still need more
information, please contact your gas supplier.

and explosions. In its natural state, propane is odorless and
colorless. You may not know all the following safety precau-
tions which can protect both you and your family from an
accident. Read them carefully now, then review them point
The odorant in escaped gas can adsorb or absorb onto or into
walls, masonry and other materials and fabrics in a room. That
will take some of the odorant out of the gas, reducing its odor
intensity.
LP-Gas may stratify in a closed area, and the odor intensity
could vary at different levels. Since it is heavier than air, there
may be more odor at lower levels. Always be sensitive to the
slightest gas odor. If you detect any odor, treat it as a serious
leak. Immediately go into action as instructed earlier.
• Learn to recognize the odor of LP-gas. Your local LP-Gas
Dealer can give you a "Scratch and Sniff" pamphlet. Use it to
nd out what the propane odor smells like. If you suspect that
your LP-Gas has a weak or abnormal odor, call your LP-Gas
Dealer.
• If you are not qualied, do not light pilot lights, perform service,
or make adjustments to appliances on the LP-Gas system. If
you are qualied, consciously think about the odor of LP-Gas
prior to and while lighting pilot lights or performing service or
making adjustments.
• Sometimes a basement or a closed-up house has a musty
smell that can cover up the LP-Gas odor. Do not try to light
pilot lights, perform service, or make adjustments in an area
where the conditions are such that you may not detect the
odor if there has been a leak of LP-Gas.
• Odor fade, due to oxidation by rust or adsorption on walls of
new cylinders and tanks, is possible. Therefore, people should
be particularly alert and careful when new tanks or cylinders
are placed in service. Odor fade can occur in new tanks, or
reinstalled old tanks, if they are lled and allowed to set too
long before relling. Cylinders and tanks which have been
out of service for a time may develop internal rust which will
cause odor fade. If such conditions are suspected to exist,
a periodic sniff test of the gas is advisable. If you have any
question about the gas odor, call your LP-gas dealer. A
periodic sniff test of the LP-gas is a good safety measure
under any condition.
• If, at any time, you do not smell the LP-Gas odorant and you
think you should, assume you have a leak. Then take the
same immediate action recommended above for the occasion
when you do detect the odorized LP-Gas.
• If you experience a complete "gas out," (the container is un-
der no vapor pressure), turn the tank valve off immediately.
If the container valve is left on, the container may draw in
some air through openings such as pilot light orices. If this
occurs, some new internal rusting could occur. If the valve is
left open, then treat the container as a new tank. Always be
sure your container is under vapor pressure by turning it off
at the container before it goes completely empty or having it
relled before it is completely empty.
• Do not operate electric switches, light matches, use your
phone. Do not do anything that could ignite the gas.
• Get everyone out of the building, vehicle, trailer, or area. Do
that IMMEDIATELY.
• Close all gas tank or cylinder supply valves.
• LP-Gas is heavier than air and may settle in low areas such
as basements. When you have reason to suspect a gas leak,
keep out of basements and other low areas. Stay out until
reghters declare them to be safe.
• Use your neighbor's phone and call a trained LP-Gas service
person and the re department. Even though you may not
continue to smell gas, do not turn on the gas again. Do not
re-enter the building, vehicle, trailer, or area.
• Finally, let the service man and reghters check for escaped
gas. Have them air out the area before you return. Properly
trained LP-Gas service people should repair the leak, then
check and relight the gas appliance for you.
SOME POINTS TO REMEMBER
NO ODOR DETECTED - ODOR FADE
LP-GAS WARNING ODOR
If a gas leak happens, you should be able to smell the gas because of the odorant put in the LP-Gas.
That's your signal to go into immediate action!
SAFETY INFORMATION FOR USERS OF LP-GAS

27525-2-0411 Page 5
Unvented Room Heater and should be installed according to these
instructions.
Any alteration of the original design, installed other than as
shown in these instructions or use with a type of gas not
shown on the rating plate is the responsibility of the person
and company making the change.
Important
All correspondence should refer to complete Model Number, Serial
Number and type of gas.
Attention: During initial use of ceramic log you will detect
an odor as the ceramic log is cured. Also, during the curing

Notice: During initial ring of this unit, its paint will bake out, and
smoke will occur. To prevent triggering of smoke alarms, ventilate
the room in which the unit is installed.
Installation on Rugs and Tile
If this appliance is installed directly on carpeting, tile or other
combustible material other than wood ooring the appliance shall
be installed on a metal or wood panel extending the full width and
depth of the appliance.
The base referred to above does not mean the re-proof base as
used on wood stoves. The protection is for rugs that are extremely
thick and light colored tile.
Solid-fuels shall not be burned in a masonry or UL 127 factory-built
replace in which an unvented room heater is installed.

Installation and replacement of gas piping, gas utilization equip-
ment or accessories and repair and servicing of equipment shall
be performed only by a qualied agency. The term "qualied
agency" means any individual, rm, corporation or company which
either in person or through a representative is engaged in and is
responsible for (a) the installation or replacement of gas piping or
(b) the connection, installation, repair or servicing of equipment, who
is experienced in such work, familiar with all precautions required
and has complied with all the requirements of the authority having
jurisdiction.
State of Massachusetts: The installation must be made by a
licensed plumber or gas tter in the Commonwealth of Mas-
sachusetts.
Sellers of unvented propane or natural gas-red supplemental
room heaters shall provide to each purchaser a copy of 527
CMR 30 upon sale of the unit.
In the State of Massachusetts, unvented propane and natural
gas-red space heaters shall be prohibited in bedrooms and
bathrooms.
The installation must conform with local codes or, in the absence of
local codes, with the National Fuel Gas Code, ANSI Z223.1.*
*Available from theAmerican National Standards Institute, Inc. 1430
Broadway, New York, N.Y. 10018.
High Altitudes
For altitudes/elevations above 2,000 feet (610m), ratings should be
reduced at the rate of 4 percent for each 1,000 feet (305m) above
sea level. Contact the manufacturer or your gas company before
changing spud/orice size.
WARNING
Failure to keep the primary air opening(s) of the burner(s)
clean may result in sooting and property damage.
Instructions to Installer
1. Installer must leave instruction manual with owner after
installation.
2. Installer must have owner ll out and mail warranty card supplied
with unvented room heater.
3. Installer should show owner how to start and operate unvented
room heater.
Always consult your local Building Department regarding regula-
tions, codes or ordinances which apply to the installation of an
unvented room heater.
This appliance may be installed in an aftermarket* manufactured
(mobile) home, where not prohibited by state or local codes.
*Aftermarket: Completion of sale, not for purpose of resale, from
the manufacturer.
This appliance is only for use with the type of gas indicated on the
rating plate. This appliance is not convertible for use with other
gases.
Well Head Gas Installations
Some natural gas utilities use "well head" gas. This may affect the
Btu output of the unit. Contact the gas company for the heating value.
Contact the manufacturer or your gas company before changing
spud/orice size.
WARNING
ANY CHANGE TO THIS HEATER OR ITS CONTROLS CAN
BE DANGEROUS.
Improper installation or use of the heater can cause seri-
         
monoxide poisoning.
Operation
This unvented replace requires no outside venting. This unvented
replace is designed for vent-free operation with ue damper closed.
State and local codes in some areas prohibit the use of unvented
replace.
VFD26F(M,P)3 Series, Millivolt controls
The valve regulator controls the burner pressure which should be
checked at the pressure test point. Turn captured screw counter
clockwise 2 or 3 turns and then place tubing to pressure gauge over
test point (Use test point “A” closest to control knob). After taking
pressure reading, be sure and turn captured screw clockwise rmly
to re-seal. Do not over torque. Check for gas leaks.
Millivolt System
When you ignite the pilot, the thermocouple produces millivolts
(electrical current) which energizes the magnet in the gas valve.
After 30 seconds to 1 minute time period you can release the gas
control knob and the pilot will stay ON. Allow your pilot ame to
operate an additional one (1) to two (2) minutes before you turn the
gas control knob from the PILOT position to the ON position. This
time period allows the millivolts (electrical current) to build-up to a
sufcient level allowing the gas control to operate properly.
WARNING
This appliance is equipped for (natural gas or propane) gas. Field
conversion is not permitted.
General Information
This series is design certied in accordance with American National
Standard Z21.11.2 by the Canadian Standards Association as an
INTRODUCTION

27525-2-0411Page 6
BUILT-IN FIREPLACE INSTALLATION
Built-In Fireplace Installation
Built-in installation of this replace involves installing the replace
into a framed-in enclosure. This makes the front of the replace
ush with a wall. If installing a mantel above the replace, you
must follow the clearances shown in Figure 9. Follow the instruc-
tions below to install the replace in this manner.
Frame in rough opening. Use dimensions show in Figure 1 for a
conventional rough opening. Use dimensions shown in Figure 2
for corner rough opening. Be sure to provide gas line for replace
and electrical power for optional blower assembly.
1. Attach two (2) nailing anges to rebox sides with two (2) 10
x 1/2" screws for each nailing ange.
2. Gas line connections must be made at this time. When facing
the appliance, the gas supply will enter on the right-hand side.
See "Gas Supply" page 11.
3. Insert replace into enclosure.
4. Attach nailing anges to framing with a screw or nail.
5. Finished wall surface will be ush to the leading edge of re-
place top and sides.
6. Installation of built-in replace is completed. Figure 2
Figure 3
Figure 1
Rough Opening for Installing in Wall
Rough Opening for Installing in Corner

27525-2-0411 Page 7
FIREPLACE DIMENSIONS
GAS LINE
OPENING JUNCTION BOX
ASSEMBLY
GAS LINE
OPENING
J
I
K
B
C
G
AD
E
Figure 4
VFD26 Series Dimensions
Index Letter Dimension
A30 1/4"
768mm
B30"
762mm
C13 1/8"
333mm
D18 1/8"
460mm
E26"
660mm
G25"
635mm
I36 1/4"
921mm
J36 1/4"
921mm
K51 1/4"
1302mm

27525-2-0411Page 8
SPECIFICATIONS
Model VFD26F(M,P)3 VFD26F(M,P)2 VFD26FP30L10
Input Maximum 20,000 20,000 10,000
Minimum 14,000 14,000 N/A
NAT
Orice 2.10 mm (P-288) #49 (.073") P-265 #53 (.0595") P-214
Air Shutter Opening 1/8" 1/8" 1/8"
LP
Orice #55 (.052") P-182 #55 (.052") P-182 #64 (.036") P-193
Air Shutter Opening 1/4" 1/4" 1/4"
Fireplace Dimensions
Height 30 1/4" 30 1/4" 30 1/4"
Depth 13 1/8" 13 1/8" 13 1/8"
Front Width 30" 30" 30"
Rear Width 25" 25" 25"
Gas Inlet 3/8" 3/8" 3/8"
Accessories
FBBX Blower Extension Kit (MUST order FBB4)
FBB4 Automatic Blower (MUST order FBBX)
VPS26HP Bottom Trim Kit
VF2H26HP Hammered Pewter Hood Kit
VPF26HP Hammered Pewter Trim Kit
FPP26E Brick Liner
VPL26HP Hammered Pewter Slat Louver
Accessories for Millivolt VFD26F(M,P)3 Only
FRBC Battery Operated Remote Control
FRBTC Battery Operated Remote Control w/Thermostat
FREC Electric Remote Control
FWS-1 Wall Switch
TMV Wall Thermostat, Millivolt - Reed Switch
TRW Wireless Remote Wall Thermostat
Water vapor is a by-product of gas combustion. An unvented room
heater produces approximately one (1) ounce (30ml) of water for
every 1,000 BTU's (.3KW's) of gas input per hour. .
Unvented room heaters are recommended as supplemental heat (a
room) rather than a primary heat source (an entire house). In most
supplemental heat applications, the water vapor does not create a
problem. In most applications, the water vapor enhances the low
humidity atmosphere experienced during cold weather.
The following steps will help insure that water vapor does not
become a problem.
1. Be sure the heater is sized properly for the application, including
ample combustion air and circulation air.
2. If high humidity is experienced, a dehumidier may be used to
help lower the water vapor content of the air.
3. Do not use an unvented room heater as the primary heat
source.
WATER VAPOR: A BY-PRODUCT OF UNVENTED ROOM HEATERS

27525-2-0411 Page 9
3. Add the BTU/Hr of all fuel burning appliances in the space.
Vent-free heater BTU/Hr
Gas water heater BTU/Hr
Gas furnace BTU/Hr
Vented gas heater BTU/Hr
Gas replace logs BTU/Hr
Other gas appliances* + BTU/Hr
Total = BTU/Hr
Example: Vented gas heater 20,000 BTU/Hr
Vent-free heater + 18,000 BTU/Hr
Total = 38,000 BTU/Hr
*Do not include direct-vent gas appliances. Direct vent draws
combustion air from the outdoors and vents to the outdoors.
4. Compare the maximum BTU/Hr the space can support with the
actual amount of BTU/Hr used.
BTU/Hr (maximum the space can support)
BTU/Hr (actual amount of BTU/Hr used)
Example:
25,600 BTU/Hr (maximum the space can support)
38,000 BTU/Hr (actual amount of BTU/Hr used)
WARNING
If the area in which the heater may be operated is smaller than that
dened as an unconned space or if the building is of unusually
tight construction, provide adequate combustion and ventilation
air by one of the methods described in the National Fuel Gas
Code, ANSI Z223.1/NFPA 54, Air for Combustion and Ventilation,
or applicable local codes.
The space in the above example is a conned space because the
actual BTU/Hr used is more than the maximum BTU/HR the space
can support. You must provide additional fresh air. Your options
are as follows:
A. Rework worksheet, adding the space of an adjoining room. If
the extra space provides an unconned space, remove door
to adjoining room or add ventilation grills between rooms. See
Ventilation Air From Inside Building.
B. Vent room directly to the outdoors. See Ventilation Air From
Outdoors.
C. Install a lower BTU/Hr heater, if lower BTU/Hr size makes room
unconned.
If the actual BTU/Hr used is less than the maximum BTU/Hr the
space can support, the space is an unconned space. You will need
no additional fresh air ventilation.
WARNING

space.
This heater shall not be installed in a conned space or unusu-
ally tight construction unless provisions are provided for adequate
combustion and ventilation air.
A conned space is an area with volume less than 50 cubic feet per
1,000 Btuh of the combined input rates of all appliances drawing
combustion air from that space. Small areas such as equipment
rooms are conned spaces. Furnaces installed in a conned space
which supply heated air to areas outside the space must draw return
air from outside the space through tightly sealed return air ducts. A
conned space must have 2 openings into the space for combus-
tion air. One opening must be within 12 inches of the ceiling and
the other must be within 12 inches of the oor. The required sizing
of these openings is determined by whether inside or outside air is
used to support combustion, the method by which the air is brought
to the space (vertical or horizontal duct) and by the total input rate
of all appliances in the space.
Unusually Tight Construction
The air that leaks around doors and windows may provide enough
fresh air for combustion and ventilation. However, in buildings of
unusually tight construction, you must provide additional fresh air.
      
where:
a. Walls and ceilings exposed to the outside atmosphere have
a continuous water vapor retarder with a rating of one perm
or less with openings gasketed or sealed, and
b. Weatherstripping has been added on openable 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 at
other openings.
If your home meets all of the three criteria above, you must provide
additional fresh air. See “VentilationAir From Outdoors,” page
10.

Use this worksheet to determine if you have a conned or unconned
space.
Space: Includes the room in which you will install heater plus any
adjoining rooms with doorless passageways or ventilation grills
between the rooms.
1. Determine the volume of the space (length x width x height).
Length x Width x Height = cu. ft. (volume of
space)
Example: Space size 16 ft. (length) x 10 ft. (width) x 8 ft. (ceiling
height) = 1,280 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills
or openings, add the volume of these rooms to the total volume
of the space.
2. Divide the space volume by 50 cubic feet to determine the
maximum BTU/Hr the space can support.
(volume of space) ÷ 50 cu. ft. = (maximum
BTU/Hr the space can support)
Example: 1,280 cu. ft. (volume of space) ÷ 50 cu. ft. = 25.6 or
25,600 (maximum BTU/Hr the space can support)
PROVISIONS FOR ADEQUATE COMBUSTION & VENTILATION AIR

27525-2-0411Page 10
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining unconned space. When
ventilating to an adjoining unconned space, you must provide two
permanent openings: one within 12" of the ceiling and one within
12" of the oor on the wall connecting the two spaces (see options
1 and 2, Figure 5). You can also remove door into adjoining room
(see option 3, Figure 5). Each ventilation grill or opening shall have
a minimum free area of one square inch per 1,000 BTU/HR of the
total input rating of the gas equipment in the conned space.
Figure 5
WARNING
Rework worksheet, adding the space of the adjoining

fresh air to supply all appliances in both spaces.
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills or ducts. You must
provide two permanent openings: one within 12" of the ceiling and
one with 12" of the oor. Connect these items directly to the outdoors
or spaces open to the outdoors. These spaces include attics and
crawl spaces. In most cases for direct communication with the
outdoors or direct communication through a vertical duct a free
area opening of one square inch per 4,000 BTU/HR of heater input
rating for each grill. If a horizontal duct is used, a grill free area or
duct opening shall have a free area opening of one square inch per
2,000 BTU/HR for each grill. Follow the National Fuel Code, ANSI
Z223.1/NFPA 54, Air for Combustion and Ventilation, or applicable
local codes, for required size of ventilation grills or ducts.
IMPORTANT: Do not provide openings for inlet or outlet air into attic
if attic has a thermostat-controlled power vent. Heated air entering
the attic will activate the power vent.
Figure 6
PROVISIONS FOR ADEQUATE COMBUSTION & VENTILATION AIR