Natco F85H Fire Coil 85 200 User manual

WARNING
If the information in this manual is not
followed exactly, a fire or explosion may
result causing property damage, personal
injury or loss of life.
Do not store or use gasoline or other
flammable 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.
• Immediately call your gas supplier from
a nearby 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 qualified installer, service agency, or gas
supplier.
Installation and Operation Instructions Document 1240
H2341100-
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualified in hot water boiler installation and maintenance. Improper installation and/or operation could
create carbon monoxide gas in flue gases which could cause serious injury, property damage, or
death. Improper installation and/or operation will void the warranty. For indoor installations, as an
additional measure of safety, NATCO strongly recommends installation of suitable Carbon Monoxide
detectors in the vicinity of this appliance and in any adjacent occupied spaces.
AVERTISSEMENT
Assurez-vous de bien suivres les instructions
données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion ou
pour éviter tout dommage matériel, toute blessure
ou la mort.
Ne pas entreposer ni utiliser d’essence ni d’autres
vapeurs ou liquides inflammables dans le voisinage
de cet appareil ou de tout autre appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ:
• Ne pas tenter d’allumer d’appareils.
• Ne touchez à aucun interrupteur. Ne pas vous
servirdestéléphonesdanslebâtimentoùvous
trouvez.
• Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions
du fournisseur.
• Si vous ne pouvez rejoindre le fournisseur de
gaz, appelez le sservice des incendies.
L’installation et l’entretien doivent être assurés par
un installateur ou un service d’entretien qualifié ou
par le fournisseur de gaz.
Installation and Operation
Instructions for
Fire Coil 85
Hydronic Boiler
Model F85H
Water Heater
Model F85V
Sizes 200, 300, 400

National Combustion Co., Inc.
Page 2
SECTION 1. General Information
1.1 Introduction......................................................3
1.2 Model Identification..........................................4
1.3 Warranty ..........................................................4
1.4 Dimensions......................................................4
1.5 Locating the Appliance..................................... 4
1.6 Locating Pump-Mounted Water Heater
with Respect to Storage Tank(s)......................7
1.7 Locating Pump-Mounted Boiler with
Respect to Return/Supply Header...................7
1.8 Locating Appliance for Correct Horizontal Vent/
Ducted Air Distance From Outside Wall ..........7
SECTION 2. Venting and Combustion Air
2.1 Combustion Air ................................................ 8
2.1.1 Combustion Air From Room ............................8
2.1.2 Intake Combustion Air...................................... 9
2.2 Venting.............................................................9
2.2.1 Vent Categories...............................................9
2.2.2 Category I Vent................................................9
2.2.3 Common Venting Systems ..............................9
2.2.4 Category III Vent............................................10
2.3 Locating Vent & Combustion Air Terminals....10
2.3.1 Side Wall Vent Terminal.................................10
2.3.2 Side Wall Combustion Air Terminal................13
2.3.3 Vertical Vent Terminal.................................... 13
2.3.4 Vertical Combustion Air Terminal................... 13
2.4 Common Vent Test – Boilers .........................13
2.5 Vent Terminals for Outdoor Units...................14
SECTION 3. Gas Supply and Piping
3.1 Gas Supply and Piping..................................15
SECTION 4A. Water Connections –
Boiler
4A.1 Heating System Piping:
Hot Supply Connections – Boiler...................16
4A.2 Cold Water Make-Up – Boiler........................16
4A.3 Water Flow Requirements – Boiler................16
4A.4 Freeze Protection – Boiler.............................16
SECTION 4B. Water Connections –
Water Heater
4B.1 Water System Piping – Water Heater............20
4B.2 Hot Water Supply Piping – Water Heater ......20
4B.3 Water Flow Requirements – Water Heater....20
4B.4 Combined Water (potable)
Heating and Space Heating...........................20
4B.5 Freeze Protection – Water Heater.................21
SECTION 5. Electrical Connections
5.1 Main Power....................................................24
5.2 Field Wiring ...................................................25
SECTION 6. Operating Instructions
6.1 Filling the Boiler System................................29
6.2 Operating Temperature Control..................... 29
6.3 External Boiler Operations.............................29
6.4 Sequence of Operation..................................30
6.5 Ignition Control Reaction to Air Flow/
Blocked Vent Pressure Switch.......................30
6.6 Operating the Burner and Set Up..................31
6.6.1 Set Up for 0 to 2500 Feet Altitude..................31
6.6.2 High Altitude Adjustment and Set Up.............31
6.7 Shutting Down the Fire Coil 85......................31
6.8 To Restart the Fire Coil 85.............................32
SECTION 7. Maintenance
7.1 System Maintenance.....................................32
7.2 Appliance Maintenance and
Component Description.................................32
7.2.1 Burners..........................................................33
7.2.2 Filter...............................................................33
7.2.3 Gas Valves.....................................................33
7.2.4 Manual Reset High Limit Control...................33
7.2.5 Ignition Control...............................................33
7.2.6 Ignitor.............................................................33
7.2.7 Transformer ...................................................33
7.2.8 Flow Switch....................................................34
7.2.9 Heat Exchanger Coil......................................34
SECTION 8. Trouble Shooting
8.1 Resolving Lockouts........................................35
8.2 Delayed Ignition – Possible Causes..............35
8.3 Short Cycling – Boiler....................................35
8.4 Short Cycling – Water Heater........................35
8.5 High Gas Consumption..................................35
SECTION 9. Replacement Parts
9.1 General Information.......................................36
9.2 Parts List........................................................36
TABLE OF CONTENTS

Fire Coil 85 (200, 300, 400) Page 3
SECTION 1.
General Information
USING THIS MANUAL– Because the Fire
Coil 85 Boilers and Fire Coil 85 Water Heaters are
identical appliances, with the exception of materials
of manufacture, labels and ultimate use application,
this manual provides information for the proper
installation, operation and maintenance of both
products. Where differences exist between the
application of the appliances and their operation,
the sections pertinent to only one appliance or the
other will be so identified.
In the Commonwealth of Massachusetts, this
appliance must be installed by a licensed plumber or
gas fitter.
WARNING
To minimize the risk of electric shock, fire or other
hazards which could result in property damage,
injury, or death. The Fire Coil 85 hydronic, boiler
or water heater must be installed in accordance
with the procedures detailed in this manual, or the
NATCO warranty may be voided. The installation
must conform to the requirements of the local
jurisdiction having authority, and, in the United
States, to the latest edition of the National Fuel
Gas Code, ANSI Z223.1/NFPA54. In Canada, the
installation must conform to the latest edition of
the Natural Gas and Propane Installation Code,
CSA B149.1 and/or applicable local codes. Where
required by the authority having jurisdiction, the
installation of Fire Coil 85 appliances must conform
to the Standard for Controls and Safety Devices
for Automatically Fired Boilers, ANSI/ASME
CSD-1. Any modifications to the boiler, its gas
controls, or wiring may void the warranty. If field
conditions require modifications, consult the factory
representative before initiating such modifications.
1.1 Introduction
This manual provides information necessary for
the installation, operation, and maintenance of NATCO
Fire Coil 85 copper tube appliances, sizes 200-400
MBTU/hr (larger models are covered in a separate
manual). Read it carefully before installation.
AVERTISSEMENT
Afin de réduire au minimum les risques de
commotion électrique, de feu ou d’autre nature,
qui pourraient causer des dommages matériels,
des blessures ou des accidents mortels, les
chaudières à eau chaude ou les chauffe-eau Fire
Coil 85 doivent être installés conformément aux
directives détaillées contenues dans ce manuel,
à défaut de quoi la garantie fournie par NATCO
Heating Systems serait annulée. L’installation doit
être conforme aux exigences de la réglementation
locale en vigueur et, aux États-Unis, à l’édition
la plus récente du Natural Fuel Gas Code (Code
pour le gaz combustible naturel) ANSI Z223.1/
NFPA54.Au Canada, l’installation doit respecter
les exigences de la plus récente édition du Code
d’installation du gaz naturel et du propane CSA
B149.1, et/ou des codes locaux de construction en
vigueur. Lorsque la réglementation locale l’exige,
l’installation des appareils électroménagers Fire
Coil 85 doit respecter les exigences du Standard
for Controls and Safety Devices for Automatically
Fired Boilers (Code pour les équipements de
commande et de sécurité des chaudières à
combustion automatique), ANSI/ASME CSD-
1. Toute modification apportée à la chaudière,
aux régulateurs de gaz ou au câblage, peut
compromettre la garantie. Si certaines conditions
particulières rendent des adaptations nécessaires,
consulter un représentant du fabricant avant
d’entreprendre ces modifications.
All application and installation procedures should
be reviewed completely before proceeding with the
installation. Consult National Combustion Co., or local
representative, with any issues or questions regarding
this equipment. Experience has shown that most
operating issues are caused by improper installation.
The Fire Coil 85 appliance is protected against
over pressurization. A pressure relief valve is fitted to
all appliances. It is installed on the outlet header, at the
water outlet of the appliance.
IMPORTANT: The inlet gas pressure to the appliance
must not exceed 13 in. w.c. (3.2 kPa).
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
F 8 5 A C 1
SERIES
F 8 5 USAGE H
V
SIZE
0 2 0 0
0 3 0 0
0 4 0 0
FUEL
N
P
ALTITUDE
AFIRING
MODE
C
K
LOCATION
CREVISION 1HEAT
EXCHANGER
B
C
N
P
2
5
OPTIONS
CODE
X
L
PUMP
OPTIONS
X
N
S

National Combustion Co., Inc.
Page 4
All installations must be made in accordance with:
1) In the U.S., the " National Fuel Gas Code "ANSI
Z223.1/NFPA54, Latest Edition and all applicable
local codes as required by the Authorities Having
Jurisdiction (AHJ), or
2) In Canada, the "Natural Gas and Propane
Installation Code", CSA B149.1, latest edition and all
applicable local codes as required by the AHJ.
All electrical wiring is to be done in accordance with:
1). In the U.S., the "National Electrical Code" (NEC),
ANSI/NFPA 70, latest Edition and all applicable local
codes as required by the AHJ, or
2). In Canada, the “Canadian Electrical Code - Part
1”, CSA STD. C22.1 and all applicable local codes as
required by the AHJ.
This appliance must be electrically grounded in
accordance with the applicable codes and standards
referenced above.
1.2 Model Identification
Consult the rating plate on the unit. The
following information describes the model number
structure.
Model Character Designation
1-3 Model Series Designation
F 8 5 = Fire Coil 85
4 Usage
H = Hydronic
V = Volume Water
5-8 Size
0 2 0 0 = 199,900 BTU/h input
0 3 0 0 = 299,000 BTU/h input
0 4 0 0 = 399,900 BTU/h input
9 Fuel
N = Natural Gas
P = Propane
10 Altitude
A = 0-10,000 feet
11 Location
C = Indoor and Outdoor
12 Firing Mode
C = On-Off (standard)
K = Two-stage (optional)
13 Revision
1 = Revision Level 1
14 Heat Exchanger
B = Glass-lined CI / copper / brz trim (std. F85V)
C = Glass-lined cast iron / copper (std. F85H)
N = Glass-lined cast iron / cu-nickel
P = Glass-lined cast iron / cu-nickel / brz trim
2 = Glass-lined cast iron / copper, brz trim, HLW
5 = Glass-lined cast iron / cu-nickel / brz, HLW
15 Options Code
X = Standard unit
L = Low temperature control (std. F85V)
16 Pump Options
X = No Pump
N = Pump mounted, normal pump
S = Pump mounted, soft water pump (F85V only)
1.3 Warranty
NATCO Fire Coil 85 appliances are covered
by a limited warranty. The owner should fill out the
warranty registration card and return it to NATCO.
All warranty claims must be made to an
authorized NATCO representative or directly to the
factory. Claims must include the serial number and
model (this information can be found on the rating
plate), installation date, and name of the installer.
Shipping costs are not included in the warranty
coverage.
Some accessory items are shipped in separate
packages. Verify receipt of all packages listed on
the packing slip. Inspect everything for damage
immediately upon delivery, and advise the carrier of
any shortages or damage. Any such claims should be
filed with the carrier. The carrier, not the shipper, is
responsible for shortages and damage to the shipment
whether visible or concealed.
1.4 Dimensions
See Figures 1A and 1B.
1.5 Locating the Appliance
The appliance should be located to provide
clearances on all sides for maintenance and inspection.
It should not be located in an area where leakage of
any connections will result in damage to the area
adjacent to the appliance or to lower floors of the
structure.
When such a location is not available, it is
recommended that a suitable drain pan, adequately
drained, be installed under the appliance.
The appliance is design certified by CSA-
International for installation on combustible flooring;
in basements; in closets, utility rooms or alcoves. Fire
Coil 85 Boilers or Water Heaters must never be
installed on carpeting. The location for the appliance
should be chosen with regard to the vent pipe lengths
and external plumbing. The unit shall be installed
such that the gas ignition system components are
protected from water (dripping, spraying, rain, etc.)
during operation and service (circulator replacement,
control replacement, etc.). When vented vertically,
the Fire Coil 85 must be located as close as practical
to a chimney or outside wall. If the vent terminal and/
or combustion air terminal terminate through a wall,
and there is potential for snow accumulation in the
local area, both terminals should be installed at an
appropriate level above grade such that blockage of
the terminal from accumulated debris or precipitation
is prevented.

Fire Coil 85 (200, 300, 400) Page 5
Figure 1A. Dimensional Data - Non Pump Mounted.
*Air and vent connections may be on top or back of the Fire Coil 85, and are field convertible.
Model A Combustion Air Connection
B* Vent Connection
C* Horizontal
(Cat III)
Vent Pipe Size
in. cm in. cm in. cm in. cm
200 20.5 52 410 513 410
300 26.5 67 410 615 513
400 33.6 85 615 718 615
Dimensions shown in inches, cm.

National Combustion Co., Inc.
Page 6
Figure 1b. Dimensional Data - Pump Mounted.
*Air and vent connections may be on top or back of the Fire Coil 85, and are field convertible.
Model A Combustion Air Connection
B* Vent Connection
C* Horizontal
(Cat III)
Vent Pipe Size
in. cm in. cm in. cm in. cm
200 20.5 52 410 513 410
300 26.5 67 410 615 513
400 33.6 85 615 718 615
Dimensions shown in inches, cm.

Fire Coil 85 (200, 300, 400) Page 7
The dimensions and requirements that are shown
in Table 2 should be met when choosing the locations
for the appliance.
1.6 Locating Pump-Mounted Water Heater
with Respect to Storage Tank(s)
For best results, a pump-mounted Fire Coil 85
water heater should be located within 15 feet (4.6m)
of the storage tank(s). The pump is sized for 30 feet
(9.1m) of piping.
If the appliance must be installed with longer
piping runs, then larger diameter pipe or tubing may be
acceptable. Consult the factory for assistance.
1.7 Locating Pump-Mounted Boiler with
Respect to Return/Supply Header
For the best results, a pump-mounted Fire Coil
85 boiler should be located within 15 feet (4.6m) of
the supply and return headers. The pump is sized for
30 feet (9.1m) of piping.
If the appliance must be installed with longer
piping runs, then larger diameter tubing may be
acceptable. Consult the factory for assistance.
Heater
Size Vent Collar Size Horizontal Vent Pipe
Diameter
Intake
Air Collar
& Pipe
Diameter
Max. Pipe
Length Max. No. of Elbows Side Vent Terminal
Part Number
Side Wall
Combustion
Air Terminal
Part Number
in cm in cm in cm ft m
200 513 410 410 50 15 3 CA003101 CA003201
300 615 513 410 50 15 3 CA003102 CA003201
400 718 615 615 50 15 3 CA003103 CA003202
Table 1. Horizontal Vent / Combustion Air Parameters.
Appliance
Surface Required Clearance From
Combustible Material
Recommended
Service Access
Clearance
inches cm inches cm
Left Side 12.5 24 61
Right Side 12.5 24 61
Top 12.5 12 30
Back 12.5 12** 30**
Front 12.5 36 91
Vertical
(Category 1)
Vent 6* 15.2*
Horizontal
(Category 3)
Vent
per UL 1738 venting
system supplier's
instructions
*1" (2.5 cm) when b-vent is used.
**When vent and/or combustion air connects to the back,
recommended clearance is 36" (91cm).
Table 2. Clearances.
1.8 Locating Appliance for Correct
Horizontal Vent/Ducted Air Distance
From Outside Wall
The forced draft combustion air blower in the
appliance has sufficient power to pull air and vent
properly when the guidelines for horizontal air and
vent are followed (see Table 1).
NOTE: On some models, the vent collar size is
larger than the size of the vent pipe that can be
used. Vent collar size and horizontal pipe diameters
can be found in Table 1. The larger vent collar
size is to accommodate Category I (vertical) vent
systems.
NOTE: When located on the same wall, the Fire
Coil 85 combustion air intake terminal must be
installed a minimum of 12" (30cm) below the
exhaust vent terminal and separated by a minimum
of 36 inches (91cm) horizontally.
The air intake terminal must be installed high
enough to avoid blockage from snow, leaves and other
debris.

National Combustion Co., Inc.
Page 8
SECTION 2.
Venting and Combustion Air
WARNING
For indoor installations, as an additional measure of
safety, NATCO strongly recommends installation of
suitable Carbon Monoxide detectors in the vicinity of
this appliance and in any adjacent occupied spaces.
AVERTISSEMENT
Pour des installations intérieures, NATCO
recommande fortement, comme mesure de sécurité
supplémentaire, l’installation de détecteurs de
monoxyde de carbone adaptés dans le voisinage
de l’appareil et dans chacune des pièces habitées
adjacentes.
2.1 Combustion Air
Fire Coil 85 boilers and water heaters must
have provisions for combustion and ventilation air in
accordance with the applicable sections addressing
requirements for air for combustion and ventilation of
the National Fuel Gas Code, ANSI Z223.1. In Canada,
the applicable sections of the Natural Gas and Propane
Installation Code (CSA B149.1) must be followed. In
all cases any and all applicable local installation codes
must also be followed.
A Fire Coil 85 appliance may receive combustion
air from the space in which it is installed, or it can be
ducted directly to the unit from the outside. Proper
ventilation air must be provided in either case.
2.1.1 Combustion Air From Room
In the United States, the most common
requirements specify that the space shall communicate
with the outdoors in accordance with method 1 or 2,
which follow. Where ducts are used, they shall be of
the same cross-sectional area as the free area of the
openings to which they connect.
Method 1: Two permanent openings, one
commencing within 12 inches (30 cm) of the top
and one commencing within 12 inches (30 cm) of
the bottom, of the enclosure shall be provided. The
openings shall communicate directly, or by ducts,
with the outdoors or spaces that freely communicate
with the outdoors. When directly communicating
with the outdoors, or when communicating to the
outdoors through vertical ducts, each opening shall
have a minimum free area of 1 square inch per 4000
Btu/hr (5.5 square cm/kW) of total input rating of all
equipment in the enclosure. When communicating to
the outdoors through horizontal ducts, each opening
shall have a minimum free area of not less than
1 square inch per 2000 Btu/hr (11 square cm/kW) of
total input rating of all equipment in the enclosure.
Table 3 shows data for this sizing method, for each
Fire Coil 85 model.
Method 2: One permanent opening, commencing
within 12 inches (30 cm) of the top of the enclosure,
shall be permitted. The opening shall directly
communicate with the outdoors or shall communicate
through a vertical or horizontal duct to the outdoors
or spaces that directly communicate with the outdoors
and shall have a minimum free area of 1 square inch
per 3000 Btu/hr (7 square cm/kW) of the total input
rating of all equipment located in the enclosure. This
opening must not be less than the sum of the areas of
all vent connectors in the confined space.
Other methods of introducing combustion and
ventilation air are acceptable, providing they conform
to the requirements in the applicable codes listed
above.
In Canada, consult local building and safety
codes or, in absence of such requirements, follow
CSA B149.1, the Natural Gas and Propane Installation
Code.
Boiler
Model Each Opening*
Square inches Square cm
200 50 323
300 75 484
400 100 645
*Net Free Area in Square Inches / Square cm
Area indicated is for one of two openings; one at floor level
and one at the ceiling, so the total net free area could be
double the figures indicated.
This chart is for use when communicating directly with the
outdoors. For special conditions and alternate methods, refer
to the latest edition of ANSI Z223.1.
Note: Check with louver manufacturers for net free area of
louvers. Correct for screen resistance to the net free area
if a screen is installed. Check all local codes applicable to
combustion air.
Table 3. Combustion Air Openings.
Figure 2. Combustion Air and Vent Through Roof.

Fire Coil 85 (200, 300, 400) Page 9
2.1.2 Intake Combustion Air
The combustion air can be taken through the
wall, or through the roof. When taken from the wall,
it must be taken from out-of-doors by means of the
NATCO horizontal wall terminal (see Table 1). When
taken from the roof, a field-supplied rain cap or an
elbow arrangement must be used to prevent entry of
rain water (see Figure 2).
Use single-wall galvanized pipe, per Table
4, for the combustion air intake (see Table 1 for
appropriate size). Route the intake to the heater as
directly as possible. Seal all joints with tape. Provide
adequate hangers. The unit must not support the
weight of the combustion air intake pipe. Maximum
linear pipe length allowed is 50 feet (15.2m). Three
elbows have been calculated into the 50-foot (15.2m)
linear run. Subtract 10 allowable linear feet (3.0m) for
every additional elbow used (see Table 1). When fewer
than 3 elbows are used, the maximum linear pipe
length allowed is still 50 feet (15.2m).
Term Description
Pipe Single-wall galvanized steel pipe, 24 gauge
minimum (either insulated or non-insulated)
Joint Sealing Permanent duct tape or aluminum tape
Table 4. Required Combustion Air Piping Material.
The connection for the intake air pipe is on
the filter box. The Fire Coil 85 appliances may have
venting and combustion air ducting attached to the top
or the back. They are shipped with the connections
at the top. For attaching either or both pipes to the
back, the mounting flanges are reversible by removing
the mounting screws and orienting the flanges in the
desired position. Replace the screws after positioning
flanges. Run a bead of silicone around the collar and
slide the pipe over the collar. Secure with sheet metal
screws.
In addition to air needed for combustion, air
shall also be supplied for ventilation, including all air
required for comfort and proper working conditions
for personnel. The Fire Coil 85 loses less than 1
percent of its input rating to the room, but other heat
sources may be present.
2.2 Venting
2.2.1 Vent Categories
Depending upon desired Fire Coil 85 venting,
it may be considered a Category I or a Category III
appliance. In general, a vertical vent system will be
a Category I system. However, in rare instances, a
Fire Coil 85’s vertical vent system may be considered
Category III. In the U.S., the National Fuel Gas Code
(ANSI Z223.1), or in Canada the Natural Gas and
Propane Installation Code (CSA B149.1), defines a
Category I vent system, and includes rules and tables
to size these vent systems. If the Fire Coil 85’s vertical
vent system does not satisfy the criteria for Category I
venting, it must be vented as a Category III system.
All Fire Coil 85 vent systems which discharge
horizontally (without the use of a power venter) are
considered Category III vent systems.
2.2.2 Category I Vent
When vented as a Category I appliance, the
vent system must conform to the National Fuel Gas
Code (ANSI Z223.1-Latest Edition) in the U.S., or in
Canada, to the Natural Gas and Propane Installation
Code (CSA B149.1 latest edition). The vent system
must be sized and installed for a Category I Fan-
Assisted Appliance.
If chimney height is greater than 25 feet, or
if multiple units are vented into the same vertical
vent, a barometric damper must be installed on each
appliance, such that the flue draft does not exceed
(negative) 0.1 in. w.c.
If using a power venter for any type of Category
I venting, the draft should be set between (negative)
0.01 and 0.05 in. w.c.
2.2.3 Common Venting Systems
Fire Coil 85 units are Category I fan-assisted
when vented vertically and adhering to all applicable
codes. Fire Coil 85 units are not allowed to be vented
into a common horizontal vent system, unless a
properly sized vent fan is used, and the common
vent system is properly designed by the vent fan
manufacturer or a qualified engineer. When common
venting Fire Coil 85 fan-assisted unit with other
appliances through one shared vertical duct called a
“common vent”, special care must be taken by the
installer to ensure safe operation. In the event that
the common vent is blocked, it is possible, especially
for fan-assisted devices, to vent backwards through
non-operating appliances sharing the vent, allowing
combustion products to infiltrate occupied spaces.
If the appliances are allowed to operate in this
condition, serious injury or death may occur.
WARNING
Operation of appliances with a blocked common
vent may lead to serious injury or death. Safety
devices must be implemented to prevent blocked
common vent operation. If safe operation of all
appliances connected to a common vent cannot
be assured, including prevention of spillage of flue
gasses into living spaces, common venting should
not be applied, and appliances should each be
vented separately.

National Combustion Co., Inc.
Page 10
AVERTISSEMENT
Le fonctionnement d’appareils connectés à un
évent commun bouché peut provoquer de sérieuses
blessures corporelles ou la mort. Des dispositifs de
sécurité doivent être mis en place pour empêcher
que les appareils soient utilisés avec un évent
commun bouché. Si un fonctionnement sécuritaire
de tous les appareils reliés à un évent commun et si
la prévention des dégagements accidentels de gaz
de combustion dans des zones habitées ne peuvent
pas être assurés, un évent commun ne doit pas
être mis en place et les appareils doivent être munis
d’évents individuels séparés.
It is for this reason that, in addition to
following proper vent sizing, construction and safety
requirements from the National Fuel Gas Code,
ANSI Z223.1 or in Canada, from the Natural Gas and
Propane Installation Code (CSA B149.1) as well as
all applicable local codes, it is required that installers
provide some means to prevent operation with a
blocked common vent. It is suggested that a blocked
vent safety system be employed such that if the switch
from one appliance trips due to excessive stack spill or
back pressure indicating a blocked vent condition, that
all appliances attached to the vent be locked out and
prevented from operating. Note that the Fire Coil 85 is
equipped with a blocked vent safety (pressure) switch,
as shipped. However, this safety switch has only been
designed and tested to be effective in installations
where the Fire Coil 85 is vented separately and
NOT common vented with other appliances.As an
additional precaution, it is recommended that a Carbon
Monoxide (CO) alarm be installed in all enclosed
spaces containing combustion appliances. If assistance
is required in determining how a blocked vent safety
system should be connected to a NATCO product,
please call the NATCO applications department at
718-291-8400.
Refer to the installation and operating
instructions on all appliances to be common vented
for instructions, warnings, restrictions and safety
requirements. If safe operation of all appliances
connected to a common vent cannot be assured,
including prevention of spillage of flue gases into
living spaces, common venting should not be applied,
and appliances should each be vented separately.
2.2.4 Category III Vent
When the Fire Coil 85 is vented with horizontal
discharge, it must be installed per this installation
manual and the venting system manufacturer’s
installation instructions. The vent system must be
sealed stainless steel, per Table 5.
Route the vent pipe to the heater as directly as
possible. Seal all joints and provide adequate hangers
as required in the venting system manufacturer’s
installation instructions. Horizontal portions of the
venting system must be supported to prevent sagging
and may not have any low sections that could trap
condensate.
The unit must not support the weight of the vent
pipe. Horizontal runs must slope downwards not less
than ¼ inch per foot (2 cm/m) from the unit to the vent
terminal.
L’appareil ne doit pas supporter le poids de la
gaine d’évent. Les parties horizontales doivent être
installées avec une pente de 2 cm/m (1/4 inch par pied)
descendant de l’appareil vers la sortie de l’évent.
Reference Table 1 for the size of the Category
III vent system. Up to three elbows can be used with
50 linear feet (15.2m) of pipe. Subtract 10 allowable
linear feet (3.0m) for every additional elbow used.
2.3 Locating Vent & Combustion Air
Terminals
2.3.1 Side Wall Vent Terminal
The appropriate NATCO side wall vent terminal
must be used, and is listed in the installation and
operation manual. The terminal provides a means of
installing the vent piping through the building wall,
and must be located in accordance with ANSI Z223.1/
NFPA 54 and applicable local codes. In Canada, the
installation must be in accordance with CSA B149.1
and local applicable codes. Consider the following
when installing the terminal:
1. Figure 3 shows the requirements for mechanical
vent terminal clearances for the U.S. and Canada.
2. Locate the vent terminal so that vent gases cannot
be drawn into air conditioning system inlets.
3. Locate the vent terminal so that vent gases cannot
enter the building through doors, windows,
gravity inlets or other openings. Whenever
possible, locations under windows or near doors
should be avoided.
4. Locate the vent terminal so that it cannot be
blocked by snow. The installer may determine
that a vent terminal must be higher than the
minimum shown in codes, depending upon local
conditions.
5. Locate the terminal so the vent exhaust does
not settle on building surfaces or other nearby
objects. Vent products may damage such surfaces
or objects.
Term Description
Pipe Must comply with UL Standard 1738 such
as Type AL29-4C Stainless Steel
(either insulated or non-insulated).
Joint
Sealing Follow vent manufacturer's instructions.
Table 5. Required Horizontal Venting Material.

Fire Coil 85 (200, 300, 400) Page 11
U.S. Installations (see note 1) Canadian Installations (see note 2)
A= Clearance above grade, veranda, porch, 12 inches (30 cm) 12 inches (30 cm)
deck, or balcony
B= Clearance to window or door that may Direct Vent Only: 12 inches (30 cm)
be opened Other Than Direct Vent: 4 feet (1.2 m) below or 36 inches (91 cm)
to side of opening; 1 foot (30 cm) above opening
C= Clearance to permanently closed window See note 4 See note 5
D= Vertical clearance to ventilated soffit located
above the terminal within a horizontal See note 4 See note 5
distance of 2 feet (61cm) from the center line of the terminal
E= Clearance to unventilated soffit See note 4 See note 5
F= Clearance to outside corner See note 4 See note 5
G= Clearance to inside corner See note 4 See note 5
H= Clearance to each side of center line See note 4 3 feet (91 cm) within a height 15 feet
extended above meter/regulator assembly above the meter/regulator assembly
I= Clearance to service regulator vent outlet See note 4 3 feet (91 cm)
J= Clearance to non mechanical air supply Direct Vent Only: 12 inches (30 cm)
inlet to building or the combustion air inlet Other Than Direct Vent: 4 feet (1.2 m) below or 36 inches (91 cm)
to any other appliance to side of opening; 1 foot (30 cm) above opening
K= Clearance to a mechanical air supply inlet 3 feet (91 cm) above if within 10 feet (3 m) 6 feet (1.83 m)
horizontally
L= Clearance above paved sidewalk or paved Vent termination not allowed in this location Vent termination not allowed in this
driveway located on public property location
M= Clearance under veranda, porch, deck, See note 4 12 inches (30 cm) (see note 3)
or balcony
Notes:
1. In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code.
2. In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code.
3. Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
4. For clearances not specified in ANSI Z223.1 / NFPA 54, clearance is in accordance with local installation codes and the requirements of
the gas supplier.
5. For clearances not specified in CSA B149.1, clearance is in accordance with local installation codes and the requirements of the gas
supplier.
Figure 3. Vent Terminal Clearance.

National Combustion Co., Inc.
Page 12
6. If the boiler or water heater uses ducted
combustion air from an intake terminal located
on the same wall, locate the vent terminal at least
3 feet (0.9m) horizontally from the combustion
air terminal, and locate the vent terminal at least
1 foot (0.3m) above the combustion air terminal.
WARNING
The outdoor vent terminal gets hot. Unit must be
installed in such a way as to reduce the risk of
burns from contact with the vent terminal.
AVERTISSEMENT
La sortie d’évent à l’extérieur devient très chaude.
Elle doit être installée de façon à réduire le risque
de brûlures au contact de l’extrémité de l’évent.
Important Note: Massachusetts Code
Requirement.
From Massachusetts Rules and Regulations 248
CMR 5.08:
(a) For all side wall horizontally vented gas
fueled equipment installed in every dwelling,
building or structure used in whole or in
part for residential purposes, including those
owned or operated by the Commonwealth and
where the side wall exhaust vent termination
is less than seven (7) feet above finished grade
in the area of the venting, including but not
limited to decks and porches, the following
requirements shall be satisfied:
1. INSTALLATION OF CARBON MONOXIDE
DETECTORS.
At the time of installation of the side wall
horizontal vented gas fueled equipment, the
installing plumber or gasfitter shall observe that
a hard-wired carbon monoxide detector with
an alarm and battery back-up is installed on
the floor level where the gas equipment is to be
installed. In addition, the installing plumber or
gasfitter shall observe that a battery operated or
hard-wired carbon monoxide detector with an
alarm is installed on each additional level of the
dwelling, building or structure served by the side
wall horizontal vented gas fueled equipment.
It shall be the responsibility of the property
owner to secure the services of qualified licensed
professionals for the installation of hard-wired
carbon monoxide detectors.
a. In the event that the side wall horizontally
vented gas fueled equipment is installed
in a crawl space or an attic, the hard-wired
carbon monoxide detector with alarm and
battery back-up may be installed on the next
adjacent floor level.
b. In the event that the requirements of this
subdivision cannot be met at the time of
completion of installation, the owner shall
have a period of thirty (30) days to comply
with the above requirements; provided,
however, that during said thirty (30) day
period, a battery operated carbon monoxide
detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE
DETECTORS.
Each carbon monoxide detector as required
in accordance with the above provisions shall
comply with NFPA 720 and be ANSI/UL 2034
listed and IAS certified.
3. SIGNAGE.
A metal or plastic identification plate shall be
permanently mounted to the exterior of the
building at a minimum height of eight (8) feet
above grade directly in line with the exhaust vent
terminal for the horizontally vented gas fueled
heating appliance or equipment. The sign shall
read, in print size no less than one-half (½) inch
in size, “GAS VENT DIRECTLY BELOW.
KEEP CLEAR OF ALL OBSTRUCTIONS”.
4. INSPECTION.
The state or local gas inspector of the side
wall horizontally vented gas fueled equipment
shall not approve the installation unless, upon
inspection, the inspector observes carbon
monoxide detectors and signage installed in
accordance with the provisions of 248 CMR
5.08(2)(a) 1 through 4.
(b) EXEMPTIONS: The following equipment is
exempt from 248 CMR 5.08(2)(a) 1 through 4:
1. The equipment listed in Chapter 10 entitled
“Equipment Not Required To Be Vented” in the
most current edition of NFPA 54 as adopted by
the Board; and
2. Product Approved side wall horizontal vented gas
fueled equipment installed in a room or structure
separate from the dwelling, building or structure
used in whole or in part for residential purposes.
(c) MANUFACTURER REQUIREMENTS
– GAS EQUIPMENT VENTING SYSTEM
PROVIDED. When the manufacturer of
ProductApproved side wall horizontally
vented gas equipment provides a venting
system design or venting system components
with the equipment, the instructions provided
by the manufacturer for installation of the
equipment and the venting system shall
include:

Fire Coil 85 (200, 300, 400) Page 13
1. Detailed instructions for the installation of the
venting system design or the venting system
components; and
2. A complete parts list for the venting system
design or venting system.
(d) MANUFACTURER REQUIREMENTS
– GAS EQUIPMENT VENTING SYSTEM
NOT PROVIDED. When the manufacturer
of a ProductApproved side wall horizontally
vented gas fueled equipment does not
provide the parts for venting the fuel gases,
but identifies “special venting systems”, the
following requirements shall be satisfied by
the manufacturer:
1. The referenced “special venting system”
instructions shall be included with the appliance
or equipment installation instructions; and
2. The “special venting systems” shall be Product
Approved by the Board, and the instructions for
that system shall include a parts list and detailed
installation instructions.
(e) Acopy of all installation instructions for all
ProductApproved side wall horizontally
vented gas fueled equipment, all venting
instructions, all parts lists for venting
instructions, and/or all venting design
instructions shall remain with the appliance
or equipment at the completion of the
installation.
2.3.2 Side Wall Combustion Air Terminal
The NATCO side wall combustion air terminal
(listed in Table 1) must be used when the unit takes
its combustion air through a duct from a side wall.
Consider the following when installing the terminal:
1. Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning fluid,
chlorinated compounds, etc.)
2. Locate the terminal so that it will not be subject
to damage by accident or vandalism.
3. Locate the combustion air terminal so that it
cannot be blocked by snow. The National Fuel
Gas Code requires that it be at least 12 inches (30
cm) above grade, but the installer may determine
it should be higher, depending upon local
conditions.
4. If the Fire Coil 85 is side-wall vented to the
same wall, locate the vent terminal at least 3
feet (0.9m) horizontally from the combustion air
terminal, and locate the vent terminal at least 1
foot (0.3m) above the combustion air terminal
(see Figure 3).
2.3.3 Vertical Vent Terminal
When the unit is vented through the roof, the
vent must extend at least 3 feet (0.9m) above the point
at which it penetrates the roof. It must extend at least
2 feet (0.6m) higher than any portion of a building
within a horizontal distance of 10 feet (3.0m), and high
enough above the roof line to prevent blockage from
snow. When the combustion air is taken from the roof,
the combustion air must terminate at least 12" (30cm)
below the vent terminal (see Figure 2).
2.3.4 Vertical Combustion Air Terminal
When combustion air is taken from the roof, a
field-supplied rain cap or an elbow arrangement must
be used to prevent entry of rain water (see Figure 2).
The opening on the end of the terminal must be at least
12" (30cm) above the point at which it penetrates the
roof, and high enough above the roof line to prevent
blockage from snow. When the vent terminates on the
roof, the combustion air must terminate at least 12"
(30cm) below the vent terminal.
2.4 Common Vent Test — Boilers
When an existing boiler is removed from a
common venting system, the common venting system
is likely to be too large for proper venting of the
appliances remaining connected to it.
At the time of removal of an existing boiler, the
following steps shall be followed with each appliance
remaining connected to the common venting system
placed in operation, while the other appliances
remaining connected to the common venting system
are not in operation.
1. Seal any unused openings in the common venting
system.
2. Visually inspect the venting system for proper
size and horizontal pitch and determine there is
non blockage or restriction, leakage, corrosion
and other deficiencies which could cause an
unsafe condition.
3. Insofar as it is practical, close all building doors
and windows and all doors between the space in
which the appliances remaining connected to the
common venting system are located and other
spaces of the building. Turn on clothes dryers
and any appliance not connected to the common
venting system. Turn on any exhaust fans, such
as range hoods and bathroom exhausts, so they
will operate at maximum speed. Do not operate a
summer exhaust fan. Close fireplace dampers.
4. Place in operation the appliance being
inspected. Follow the lighting instructions.
Adjust thermostat so appliance will operate
continuously.
5. Test for spillage at the draft hood relief opening
after 5 minutes of main burner operation. Use
the flame of a match or candle, or smoke from a
cigarette, cigar or pipe.
6. After it has been determined that each appliance
remaining connected to the common venting
system properly vents when tested as outlined

National Combustion Co., Inc.
Page 14
above, return doors, windows, exhaust fans,
fireplace dampers and any other gas burning
appliance to their previous conditions of use.
7. Any improper operation of the common venting
system should be corrected so that the installation
conforms with the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 and/or CSA B149.1,
Natural Gas and Propane Installation Codes.
When resizing any portion of the common
venting system, the common venting system
should be resized to approach the minimum size
as determined using the appropriate tables in
Appendix F in the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 and/or CSA B149.1, Natural
Gas and Propane Installation Codes.
2.4 Vérification des évents communs
— Chaudières
Lorsqu’une chaudière existante est déconnectée
du réseau d’évents commun, ce réseau d’évents
commun devient probablement trop grand pour
les appareils qui lui restent connectés. Lorsqu’une
chaudière existante est retirée, les étapes suivantes
doivent être accomplies pour chaque appareil qui
reste connecté au réseau d’évents commun utilisé,
alors que les autres appareils qui sont encore
connectés au réseau commun d’évents ne sont pas en
fonctionnement.:
1. Sceller toutes les ouvertures non utilisées du
système d'évacuation.
2. Inspecter de façon visuelle le système
d'évacuation pour déterminer la grosseur et
l'inclinaison horizontale qui conviennent et
s'assurer que le système est exempt d'obstruction,
d'étranglement, de fuite, de corrosion et autres
défaillances qui pourraient présenter des risques.
3. Dans la mesure du possible, fermer toutes les
portes et les fenêtres du bâtiment et toutes les
portes entre l'espace où les appareils toujours
raccordés au système d'évacuation sont installés
et les autres espaces du bâtiment. Mettre en
marche les sécheuses, tous les appareils non
raccordés au système d'évacuation common
et tous les ventilateurs d'extraction comme
les hottes de cuisinière et les ventilateurs des
salles de bain. S'assurer que ces ventilateurs
fonctionnent à la vitesse maximale. Ne pas faire
fonctionner les ventilateurs d'été. Fermer les
registres des cheminées.
4. Mettre l'appareil inspecté en marche. Suivre les
instructions d'allumage. Réegler le thermostat de
façon continue.
5. Faire fonctionner le brûleur principal pendant
5 min ensuite, déterminer si le coupe-tirage
déborde à l'ouverture de décharge. Utiliser la
flamme d'une allumette ou d'une chandelle ou la
fumée d'une cigarette, d'un cigare ou d'une pipe.
6. Une fois qu'il a été déterminé, selon la méthode
indiquée ci-dessus, que chaque appareil
raccordé au système d'évacuation est mis à l'air
libre de façon adéquate. Remettre les portes
et les fenêtres, les ventilateurs, les registres de
cheminées et les appareils au gaz à leur position
originale.
7. Tout mauvais fonctionnement du système
d'évacuation commun devrait être corrigé
de façon que l'installation soit conforme au
National Fuel Gas Code, ANSI Z223.1/NFPA
54 et (ou) aux codes d'installation CSA-B149.1.
Si la grosseur d'une section du système devrait
être modifié, le système devrait être modifié pour
respecter les valeurs minimales des tableaux
pertinents de l'appendice F du National Fuel Gas
Code, ANSI Z223.1/NFPA 54 et (ou) les codes
d'installation CSA-B149.1
2.5 Vent Terminals for Outdoor Units
For outdoor applications, the vent and
combustion air openings must be covered with proper
terminals to prevent rain, snow and other objects from
falling into the Fire Coil 85.
Outdoor Vent / Air kit part numbers are shown in
Table 6. These kits contain parts for both combustion
air inlet and exhaust vent connections. An angled sheet
metal assembly with louvers replaces the sheet metal
assembly with the air collar. An adapter, a 12" length
of pipe, and a rain cap are included for the exhaust
vent opening.
If local codes allow, NATCO kits are not
required for outdoor units. The installer may use
12" of appropriately sized galvanized single wall or
b-type vent pipe and a rain cap for the exhaust vent. In
addition, an appropriately sized galvanized 90° elbow,
positioned with the opening facing down, may be used
on the combustion air inlet.
Model (Size) Outdoor Vent and
Air Terminal Kit
200 CA003001
300 CA003002
400 CA003003
Table 6. Vent / Air Kits for Outdoor Units.

Fire Coil 85 (200, 300, 400) Page 15
SECTION 3.
Gas Supply and Piping
3.1 Gas Supply and Piping
Gas piping should be supported by suitable
hangers or floor stands, not by the appliance.
The Fire Coil 85’s gas train allows the user to
pipe the gas from either the right side or the left side
of the unit. As shipped, the right side of the gas train is
capped off, and there is a manual valve on the left side.
If desired, the manual valve on the left side of the gas
train may be moved to the right side, and the cap on
the right side may be moved to the left.
Review the following instructions before
proceeding with the installation.
1. Verify that the appliance is fitted for the proper
type of gas by checking the rating plate. Fire
Coil 85 appliances are equipped to operate
at elevations up to 10,000 feet (3050m). Fire
Coil 85 appliances may be adjusted to operate
properly at altitudes above 2500 feet (see Section
6.5.2) and the input will be reduced if the heating
value of the gas supply is below sea level values.
2. The maximum inlet gas pressure must not
exceed 13" w.c. (3.2kPa). The minimum inlet gas
pressure is 5 in. w.c. (1.2 kPa).
3. Refer to Table 7, size supply.
4. Run gas supply line in accordance with all
applicable codes.
5. Locate and install manual shutoff valves in
accordance with state and local requirements.
6. A sediment trap must be provided upstream of
the gas controls.
7. All threaded joints should be coated with
piping compound resistant to action of liquefied
petroleum gas.
8. The appliance and its individual shutoff valve
must be disconnected from the gas supply piping
during any pressure testing of that system at test
pressures in excess of 0.5 psig (3.45 kpa).
9. The unit must be isolated from the gas supply
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 0.5 psig (3.45 kpa).
10. The appliance and its gas connection must be
leak tested before placing it in operation.
11. Purge all air from gas lines.
WARNING
Do not use open flame to check for leaks. An open
flame could lead to explosion, which could result in
property damage, serious injury or death.
AVERTISSEMENT
Ne recherchez pas les fuites avec une flamme nue.
Une flamme nue peut provoquer une explosion qui
peut causer des dommages matériels, de sérieuses
blessures corporelles ou la mort.
NOTE: The Fire Coil 85 appliance and all other
gas appliances sharing the gas supply line must
be firing at maximum capacity to properly measure
the inlet supply pressure. The pressure can be
measured at the supply pressure port on the gas
valve. Low gas pressure could be an indication of
an undersized gas meter, undersized gas supply
lines and/or an obstructed gas supply line.
Distance from Gas Meter or Last Stage Regulator
Model and
Gas Type 0-100' 0-31 m 100-200' 31-61m 200-300' 61-91m
200 natural 1¼" 3.2 cm 1¼" 3.2 cm 1¼" 3.2 cm
200 propane 1" 2.5 cm 1" 2.5 cm 1¼" 3.2 cm
300 natural 1¼" 3.2 cm 1½" 4.0 cm 1½" 4.0 cm
300 propane 12.5 cm 1¼" 3.2 cm 1¼" 3.2 cm
400 natural 1¼" 3.2 cm 1½" 4.0 cm 2" 5.0 cm
400 propane 1¼" 3.2 cm 1¼" 3.2 cm 1½" 4.0 cm
Notes:
1. These figures are based on 1/2" (0.12 kPa) water column pressure drop.
2. Check supply pressure and local code requirements before proceeding with work.
3. Pipe fittings must be considered when determining gas pipe sizing.
Table 7. Gas Piping Size.

National Combustion Co., Inc.
Page 16
SECTION 4A.
Water Connections —
Fire Coil 85 Boiler
4A.1 Heating System Piping:
Hot Supply Connections — Boiler
NOTE: This appliance must be installed in a closed
pressure system with a minimum of 12 psig (82.7
kPa) static pressure at the boiler.
Hot water piping should be supported by suitable
hangers or floor stands. Do not support piping with
this appliance. Due to expansion and contraction of
copper pipe, consideration should be given to the type
of hangers used. Rigid hangers may transmit noise
through the system resulting from the piping sliding in
the hangers. It is recommended that padding be used
when rigid hangers are installed. Maintain 1" clearance
to combustibles for hot water pipes.
Pipe the discharge of the relief valve (full size)
to a drain or in a manner to prevent injury in the event
of pressure relief. Install an air purger, an air vent,
a diaphragm-type expansion tank, and a hydronic
flow check in the system supply loop. Minimum fill
pressure must be 12 psig (82.7 kPa). Install shutoff
valves where required by code.
Suggested piping diagrams are shown in Figures
4, 5, 6, 7 and 8. These diagrams are meant only as a
guide. Components required by local codes must be
properly installed.
4A.2 Cold Water Make-Up — Boiler
1. Connect the cold water supply to the inlet
connection of an automatic fill valve.
2. Install a suitable back flow preventer between the
automatic fill valve and the cold water supply.
3. Install shut off valves where required.
NOTE: The boiler, when used in connection with a
refrigeration system, must be installed so the chilled
medium is piped in parallel with the boiler with
appropriate valves to prevent the chilled medium
from entering the boiler.
The boiler piping system of a hot water heating
boiler connected to heating coils located in air
handling appliances where they may be exposed to
refrigerated air circulation must be equipped with flow
control valves or other automatic means to prevent
gravity circulation of the boiler water during the
cooling cycle.
A boiler installed above radiation level, or as
required by the authority having jurisdiction, must be
provided with a low water cutoff device either as a part
of the boiler or at the time of boiler installation.
4A.3 Water Flow Requirements — Boiler
A hydronic heating (closed loop) application
recirculates the same fluid in the piping system. As a
result, no new minerals or oxygen are introduced into
the system. To ensure a proper operating temperature
leading to long boiler life, a flow rate has been
established based on the fluid temperature rise for this
specific size boiler.
Pump-mounted boilers can be ordered for use in
primary secondary piping systems. The pumps used
are sized for the head loss through the heater, plus 30
feet (9.1 m) of full-sized piping (same size as boiler
outlet) and a normal number of fittings.
Table 8 specifies water flow rates for boilers,
which will enable the user to size a pump. The head
loss shown is for the heater only, and the user will
need to add the head loss of the system piping to
properly size the pump.
The minimum inlet water temperature for the
Fire Coil 85 is 120°F (49°C) to avoid condensing on
the copper coils.
4A.4 Freeze Protection — Boiler
Boiler installations are not recommended in
areas where the danger of freezing exists unless proper
precautions are made for freeze protection. A non
toxic, heating system, anti-freeze may be added to
the hydronic system provided that the concentration
does not exceed 50% and the anti freeze contains an
anti foamant. When a 50/50 mixture is used, increase
the water flow requirements by 15%, and increase the
head loss requirements by 20%.
Power outage, interruption of gas supply, failure
of system components, activation of safety devices,
etc., may prevent a boiler from firing. Any time a
boiler is subjected to freezing conditions, and the
boiler is not able to fire, and/or the water is not able
to circulate, there is a risk of freezing in the boiler
or in the pipes in the system. When water freezes,
it expands. This can result in bursting of pipes in the
system, or damage to the boiler, which could result in
leaking or flooding conditions.
IMPORTANT NOTES: Different glycol products
may provide varying degrees of protection. Glycol
products must be maintained properly in a heating
system, or they may become ineffective. Consult
the glycol specifications, or the glycol manufacturer,
for information about specific products,
maintenance of solutions, and set up according to
your particular conditions. Never use ethylene glycol
(automotive antifreeze).

Fire Coil 85 (200, 300, 400) Page 17
Model
(Size) 20°F 25°F 30°F 35°F
flow
gpm H/L feet flow gpm H/L feet flow gpm H/L feet flow gpm H/L feet
200 17 1.6 14 1.0 11 0.7 10 0.5
300 26 3.5 20 2.3 17 1.6 15 1.2
400 34 6.3 27 4.0 23 2.8 19 2.1
Metric Equivalent
Model
(Size) 11°C 14°C 17°C 19°C
flow
lpm H/L mflow lpm H/L mflow lpm H/L mflow lpm H/L m
200 64 0.5 51 0.3 43 0.2 37 0.2
300 97 1.1 77 0.7 64 0.5 55 0.4
400 129 1.9 103 1.2 86 0.9 74 0.6
Notes: gpm = gallons per minute, lpm = liters per minute,
H/L = head loss, ft = head loss in feet,
m = head loss in meters.
Maximum temperature rise is 35°F (19°C), as shown.
Head loss is for boiler’s heat exchanger only.
N/R = not recommended.
Table 8. Water Flow Requirements - F85H.
Figure 4. Hydronic Piping — Multiple Boilers, Primary Secondary System.

National Combustion Co., Inc.
Page 18
Figure 5. Hydronic Piping — Multiple Boilers, Low Temperature System.
Figure 6. Hydronic Piping — One Boiler, Multi-Temperature System.

Fire Coil 85 (200, 300, 400) Page 19
Figure 7. Hydronic Piping — Primary-Secondary, Reverse-Return.
Figure 8. Hydronic Piping — Primary-Secondary, Reverse-Return, Low Temperature.

National Combustion Co., Inc.
Page 20
SECTION 4B.
Water Connections —
Fire Coil 85 Water Heater
4B.1 Water System Piping —
Water Heater
Hot water piping should be supported by suitable
hangers or floor stands. Do not support piping with
this appliance. Due to expansion and contraction of
copper pipe, consideration should be given to the type
of hangers used. Rigid hangers may transmit noise
through the system resulting from the piping sliding in
the hangers. It is recommended that padding be used
when rigid hangers are installed.
The Fire Coil 85 can be used with several
different types of readily available storage tanks.A
pump draws water from the storage tank and pumps
the water through the heater and back into the tank.
Pump-mounted units have a circulating pump built
into the water heater. The pumps used are sized for
the head loss through the heater, plus 30 feet (9.1 m)
of full-sized piping (same size as boiler outlet) and
a normal number of fittings. Pumps used on pump-
mounted unit are sized for soft/normal or hard water,
so make sure a pump-mounted unit matches the water
quality of the installation.
Pipe the outlet from the heater’s relief valve
such that any discharge from the relief valve will be
conducted to a suitable place for disposal when relief
occurs. Do not reduce line size or install any valves in
this line. The line must be installed to allow complete
drainage of both the valve and the line.
Suggested piping diagrams are shown in Figures
9, 10, 11 and 12. These diagrams are meant only as a
guide. Components required by local codes must be
properly installed.
Note the recommended location of the
temperature sensor on the diagrams. The Fire Coil 85
is shipped with an additional sensor that can be used
for more full-featured domestic water heating control.
To get these features, you must provide a location for
the additional sensor. It can be strapped to a pipe from
1" to 4" diameter, or inserted into a tank immersion
well. The minimum inlet water temperature for the
Fire Coil 85 is 120°F (49°C) to avoid condensing on
the copper coils. See the supplemental application
drawing for 120° (49°C) (or less) stored hot water
applications on next page.
4B.2 Hot Water Supply Piping —
Water Heater
Follow the tank manufacturer’s guidelines for
completion of the hot water system connections.
NOTE: A listed temperature and pressure relief
valve listed as complying with the Standard
for Relief Valves and Automatic Gas Shutoff
Devices for Hot Water Supply Systems (ANSI
Z21.22/CSA 4.4), of suitable discharge capacity
must be installed in the separate storage tank
system.
If the Fire Coil 85 water heater is installed in
a closed water supply system, such as one having a
backflow preventer in the cold water supply line, the
relief valve may discharge periodically, due to thermal
expansion. Means (such as a properly-sized expansion
tank) shall be provided to control thermal expansion.
Contact the water supplier or local plumbing inspector
on how to control this situation.
4B.3 Water Flow Requirements —
Water Heater
In a water heating application (an open system),
new water is constantly being introduced. With the
new water comes a fresh supply of minerals that can
be deposited on the unit’s heat exchanger. This is
commonly known as scaling. The amount of minerals
will depend upon the hardness of the water. Water can
also be aggressive, and can erode metals, including
copper, if the water is moved too quickly. The water
flow requirements for the Fire Coil 85 water heater
are based upon the hardness of the water. The water
flow is kept high enough to prevent scaling, but low
enough to prevent tube erosion. For extremely soft or
hard water, cupro-nickel tubes are available. Contact
a NATCO representative if you have questions or
concerns about water quality.
Pump-mounted water heaters can be ordered
with standard pumps for soft or normal water or with
pumps for hard water. The pumps used are sized for
the head loss through the heater, plus 30 feet (9.1m)
of full-sized piping (same size as heater outlet) and a
normal number of fittings.
Table 9 specifies water flow rates for water
heaters, which will enable the user to size a pump. The
head loss shown is for the heater only, and the user
will need to add the head loss of the piping system to
properly size the pump.
4B.4 Combined Water Heating (potable)
and Space Heating — Water Heater
NOTE: These systems are not allowed in the
Commonwealth of Massachusetts.
Piping and components connected to this water
heater for the space heating application shall be
suitable for use with potable water.
Toxic chemicals, such as used for boiler
treatment, shall not be introduced into the potable
water used for space heating.
This water heater when used to supply potable
water shall not be connected to any heating system
or component(s) previously used with a non-potable
water heating appliance.
When the system requires water for heating at