U.S. Boiler Company Alpine ALP500C Service manual

1
106307-02 - 2/17 Price - $5.00
WARNING: Improper installation, adjustment, alteration, service or maintenance can cause property damage,
injury, or loss of life. For assistance or additional information, consult a qualied installer, service agency or the
gas supplier. This boiler requires a special venting system. Read these instructions carefully before installing.
INSTALLATION, OPERATING AND
SERVICE INSTRUCTIONS FOR
ALPINE™
CONDENSING HIGH EFFICIENCY
DIRECT VENT
GAS - FIRED HOT WATER BOILER
Size Range - 399 MBH through 800 MBH
9700609
Alpine “C” Models:
• ALP399C
• ALP500C
• ALP600C
• ALP700C
• ALP800C
http://waterheatertimer.org/Two-water-heaters.html#boiler
http://waterheatertimer.org/What-size-indirect-heater.html

2
IMPORTANT INFORMATION - READ CAREFULLY
NOTE: The equipment shall be installed in accordance with those installation regulations enforced in the area where the
installation is to be made. These regulations shall be carefully followed in all cases. Authorities having jurisdiction
shall be consulted before installations are made.
All wiring on boilers installed in the USA shall be made in accordance with the National Electrical Code and/or local regulations.
All wiring on boilers installed in Canada shall be made in accordance with the Canadian Electrical Code and/or local regulations.
The following terms are used throughout this manual to bring attention to the presence of hazards of various risk levels,
or to important information concerning product life.
DANGER
Indicates an imminently hazardous situation
which, if not avoided, will result in death, serious
injury or substantial property damage.
CAUTION
Indicates a potentially hazardous situation
which, if not avoided, may result in moderate or
minor injury or property damage.
WARNING
Indicates a potentially hazardous situation
which, if not avoided, could result in death,
serious injury or substantial property damage.
NOTICE
Indicates special instructions on installation,
operation, or maintenance which are important
but not related to personal injury hazards.
WARNING
Explosion Hazard. DO NOT store or use gasoline or other ammable vapors or liquids in the vicinity of this
or any other appliance.
If you smell gas vapors, DO NOT try to operate any appliance - DO NOT touch any electrical switch or use
any phone in the building. Immediately, call the gas supplier from a remotely located phone. Follow the
gas supplier’s instructions or if the supplier is unavailable, contact the re department.

3
Special Installation Requirements for Massachusetts
A. For all sidewall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in whole or
in part for residential purposes and where the sidewall exhaust vent termination is less than seven (7) feet above grade, the
following requirements shall be satised:
1. If there is no carbon monoxide detector with an alarm already installed in compliance with the most current edition of
NFPA 720, NFPA 70 and the Massachusetts State Building Code in the residential unit served by the sidewall horizontally
vented gas fueled equipment, a battery operated carbon monoxide detector with an alarm shall be installed in compliance
with the most current edition of NFPA 720, NFPA 70 and the Massachusetts State Building Code.
2. In addition to the above requirements, if there is not one already present, a carbon monoxide detector with an alarm
and a battery back-up shall be installed and located in accordance with the installation requirements supplied with the
detector on the oor level where the gas equipment is installed. The carbon monoxide detector with an alarm shall
comply with 527 CMR, ANSI/UL 2034 Standards or CSA 6.19 and the most current edition of NFPA 720. In the event
that the requirements of this subdivision can not be met at the time of the completion of the installation of the equipment,
the installer shall have a period of thirty (30) days to comply with this requirement; provided, however, that during
said thirty (30) day period, a battery operated carbon monoxide detector with an alarm shall be installed in compliance
with the most current edition of NFPA 720, NFPA 70 and the Massachusetts State Building Code. In the event that the
sidewall horizontally vented gas fueled equipment is installed in a crawl space or an attic, the carbon monoxide detector
may be installed on the next adjacent habitable oor level. Such detector may be a battery operated carbon monoxide
detector with an alarm and shall be installed in compliance with the most current edition of NFPA 720, NFPA 70 and the
Massachusetts State Building Code.
3. A metal or plastic identication 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 (1/2) inch in size, “GAS VENT
DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS”.
4. A nal inspection by the state or local gas inspector of the sidewall horizontally vented equipment shall not be performed
until proof is provided that the state or local electrical inspector having jurisdiction has granted a permit for installation of
carbon monoxide detectors and alarms as required above.
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 sidewall horizontally 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. When the manufacturer of Product Approved sidewall horizontally vented gas equipment provides a venting system design
or venting system components with the equipment, the instructions for installation of the equipment and the venting system
shall include:
1. A complete parts list for the venting system design or venting system; and
2. Detailed instructions for the installation of the venting system design or the venting system components.
D. When the manufacturer of a Product Approved sidewall horizontally vented gas fueled equipment does not provide the parts
for venting ue gases, but identies “special venting systems”, the following shall be satised:
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. A copy of all installation instructions for all Product Approved sidewall 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.

4
TABLE OF CONTENTS
I. Product Description, Specications and Dimensional Data...................... 5
II. Unpacking Boiler........................................................................................ 9
III. Pre-Installation and Boiler Mounting.......................................................... 10
IV. Venting...................................................................................................... 15
A. General Guidelines............................................................................... 15
B. CPVC/PVC Venting.............................................................................. 22
C. Polypropylene Venting......................................................................... 27
D. Stainless Steel Venting........................................................................ 33
E. Optional Room Air for Combustion....................................................... 35
F. Removing the Existing Boiler............................................................... 36
G. Multiple Boiler Installation Venting....................................................... 37
V. Condensate Disposal................................................................................. 40
VI. Water Piping and Trim............................................................................... 42
VII. Gas Piping ............................................................................................... 54
VIII. Electrical ................................................................................................... 59
IX. System Start-Up ....................................................................................... 71
X. Operation...................................................................................................... 79
A. Overview.............................................................................................. 79
B. Supply Water Temperature Regulation................................................ 80
C. Boiler Protection Features.................................................................... 81
D. Multiple Boiler Control Sequencer........................................................ 82
E. Boiler Sequence of Operation.............................................................. 84
1. Normal Operation............................................................................ 84
2. Using the Display............................................................................ 85
3. Status Screens............................................................................... 86
4. Detail Screens................................................................................. 88
5. Multiple Boiler Sequencer Screens................................................ 89
F. Changing Adjustable Parameters......................................................... 90
1. Entering Adjust Mode..................................................................... 90
2. Adjusting Parameters...................................................................... 90
XI. Service and Maintenance ........................................................................ 109
XII. Troubleshooting........................................................................................ 116
XIII. Repair Parts ............................................................................................. 122
Appendix A - Instructions for High altitude Installations Above 2000 ft..... 135
Appendix B - Figures................................................................................ 138
Appendix C - Tables.................................................................................. 141

5
I. Product Description, Specications and Dimensional Data
Alpine Series boilers are condensing high efciency gas-
red direct vent hot water boilers designed for use in forced
hot water space or space heating with indirect domestic hot
water heating systems, where supply water temperature
does not exceed 210°F. These boilers have special coil
type stainless steel heat exchangers, constructed, tested and
stamped per Section IV ‘Heating Boilers’ of ASME Boiler
and Pressure Vessel Code, which provide a maximum heat
transfer and simultaneous protection against ue gas product
corrosion. These boilers are not designed for use in gravity
hot water space heating systems or systems containing
signicant amount of dissolved oxygen (swimming pool
water heating, direct domestic hot water heating, etc.).
Table 2: Dimensions (See Figures 1, 2, and 3)
Table 1: Specications
Specication Boiler Model
ALP399C ALP500C ALP600C ALP700C ALP800C
Altitude (ft. above sea level) 10-10,100 0-10,100 20-10,100 0-10,100 30-6,000 4
Fuel Shipped for Natural Gas, Field
Converted for LP Gas
Shipped for Natural Gas or Shipped for LP Gas
(no Field Conversion)
Max. Allowable Water Temperature (°F) 210 210 210 210 210
Max. Allowable Working Pressure (psi) 160 160 160 160 160
Factory Supplied Safety Relief Valve (psi)* 50 50 60 60 60
Boiler Water Volume (gal.) 3.4 4.3 5.4 5.4 6.2
Heat Transfer Area (sq. ft.) 41.8 58.1 76.2 76.2 87.0
Approx. Shipping Weight (lb.) 316 368 458 458 500
* Optional 80 psi and 100 psi safety relief valves are available for all models.
1 Follow Instructions for High Altitude Installations above 2000 ft. (see Appendix A)
2 ALP500C LP cannot be installed above 6,000 ft.
3 ALP700C LP cannot be installed above 7,800 ft.
4 ALP800C natural gas cannot be installed above 6,000 ft. ALP800C LP can be installed up to 10,100 ft.
Dimension
Boiler Model
ALP399C ALP500C ALP600C ALP700C ALP800C
A - Inch
(mm)
31-3/16
(792)
46-1/2
(1181)
49-1/2
(1258)
49-1/2
(1258)
53-5/16
(1258)
B - Inch
(mm)
5-1/2
(140) N/A N/A N/A N/A
C - Inch
(mm)
12-3/8
(314)
21-5/16
(541)
23-1/4
(591)
23-1/4
(591)
23-7/16
(596)
D - Inch
(mm)
23
(584)
34-13/16
(884)
38-1/16
(967)
38-1/16
(967)
41-3/16
(1046)
E - Inch
(mm)
15-1/8
(384)
28-5/16
(719)
30-7/8
(784)
30-7/8
(784)
32-9/16
(827)
Gas Inlet G - Inch 3/4 (FPT) 1 (FPT)
Return H - Inch 1-1/2 FPT 2 MPT
Supply J - Inch 1-1/2 FPT 2 MPT
PP Condensate Drain K - Inch 3/4 PVC Compression Coupling
PVC Combustion Air Connector - Inch 4
CPVC/PP/SS Vent Connector - Inch
(mm)
4
(100)
6
(150)

6
I. Product Description, Specications and Dimensional Data (continued)
Figure 1: Alpine - Model ALP399C
16 7
8
"
43 1
2
"
5 1
8
"
2 9
16
"
5 1
2
"
'B'
'C'
'D'
17 5
16
"
32 1
2
"
5 5
16
"
'E'
'A'
7 13
16
"
11
16
"
1 1
4
"
12 1
2
"
4" CPVC/PP/SS VENT CONNECTOR
LINE VOLTAGE KNOCKOUTS (120 VOLTS)
LOW VOLTAGE KNOCKOUTS (24 VOLTS)
ACCESS PANEL
ACCESS PANELACCESS PANEL
ACCESS PANEL ACCESS PANEL
'H' 1-1/2" FPT
RETURN TAPPING
'J' 1-1/2" FPT
SUPPLY TAPPING
'G'
GAS VALVE INLET
'K'
CONDENSATE DRAIN
4" PVC COMBUSTION AIR CONNECTOR
3/4" FPT
RELIEF/DRAIN
TAPPING

7
Figure 2: Alpine - Model ALP500C
I. Product Description, Specications and Dimensional Data (continued)
16 7
8
"
11
16
"
35 1
16
"
20 5
16
"
12 3
8
"
8 5
16
"
5 3
8
"
'C'
'E'
'D'
'A'
8 1
8
"
2 9
16
"
5 1
2
"
1 1
4
"
15 1
2
"
4" CPVC/PP/SS VENT CONNECTOR
'H' 2" MPT
RETURN TAPPING
'J' 2" MPT
SUPPLY TAPPING
'K'
CONDENSATE DRAIN
'G'
GAS VALVE INLET
LINE VOLTAGE
KNOCKOUTS
(120 VOLTS)
LOW VOLTAGE
KNOCKOUTS
(24 VOLTS)
ACCESS PANEL ACCESS PANEL
ACCESS PANELACCESS PANEL
ACCESS PANEL
4" PVC COMBUSTION AIR CONNECTOR

8
I. Product Description, Specications and Dimensional Data (continued)
Figure 3: Alpine - Models ALP600C, ALP700C and ALP800C
16 7
8
"
11
16
"
35 1
16
"
10 5
16
"
20 5
16
"
8 1
8
"
6 7
8
"
'C'
'E'
'D'
'A'
2 9
16
"
7 1
16
"
8 5
16
"
1 1
4
"
15 9
16
"
ACCESS PANEL ACCESS PANEL
ACCESS PANELACCESS PANEL
'H' 2" MPT
RETURN TAPPING
'J' 2" MPT
SUPPLY TAPPING
'G'
GAS VALVE INLET
'K'
CONDENSATE DRAIN
6" CPVC/PP/SS
VENT CONNECTOR
LINE VOLTAGE
KNOCKOUTS
(120 VOLTS)
LOW VOLTAGE
KNOCKOUTS
(24 VOLTS)
ACCESS PANEL
4" PVC COMBUSTION AIR CONNECTOR

9
NOTICE
Do not drop boiler.
A. Move boiler to approximate installed position.
B. Remove all crate fasteners.
C. Lift and remove outside container.
D. Remove boiler from cardboard positioning sleeve
on shipping skid.
E. Move boiler to its permanent location.
I. Product Description, Specications and Dimensional Data (continued)
Table 3: Ratings
II. Unpacking Boiler
Alpine Series Gas-Fired Boilers
Model
Number
Input (MBH) Gross Output
(MBH)
Net Ratings Water 1
(MBH)
Thermal
Efciency (%)
Combustion
Efciency (%)
Min. Max.
ALP399C 80 399 375 326 94.1 94.5
ALP500C 100 500 485 422 97.0 96.0
ALP600C 125 625 594 517 95.0 96.0
ALP700C 145 725 689 599 95.0 95.0
ALP800C 160 800 760 661 95.0 94.0
Ratings shown are for installations at sea level and elevations up to 2000 ft. at minimum vent length. For elevations above 2000
ft., see Appendix A Instructions for High Altitude Installations above 2000 ft.
1 Net AHRI Water Ratings based on allowance of 1.15. Consult manufacturer before selecting boiler for installations having
unusual piping and pickup requirements, such as intermittent system operation, extensive piping systems, etc.

10
WARNING
Explosion Hazard. Asphyxiation Hazard.
Electrical Shock Hazard. Installation of this
boiler should be undertaken only by trained
and skilled personnel from a qualied service
agency. Follow these instructions exactly.
Improper installation, adjustment, service,
or maintenance can cause property damage,
personal injury or loss of life.
NOTICE
Due to the low water content of the boiler, mis-
sizing of the boiler with regard to the heating
system load will result in excessive boiler
cycling and accelerated component failure. U.S.
Boiler Company DOES NOT warrant failures
caused by mis-sized boiler applications. DO
NOT oversize the boiler to the system. Multiple
boiler installations greatly reduce the likelihood
of boiler oversizing.
WARNING
Asphyxiation Hazard.
Apply supplied dielectric grease to gasket
inside vent connector. Failure to apply the
grease could result in ue gas leaks from gasket
rupture during vent pipe installation or gasket
deterioration due to condensate exposure.
A. Installation must conform to the requirements
of the authority having jurisdiction in or, in the absence
of such requirements, to the National Fuel Gas Code,
ANSI Z223.1/NFPA 54, and/or Natural Gas and
Propane Installation Code, CAN/CSA B149.1.
Where required by the authority having jurisdiction, the
installation must conform to the Standard for Controls
and Safety Devices for Automatically Fired Boilers,
ANSI/ASME CSD-1.
B. Boileriscertiedfor installation on combustible
ooring. Do not install boiler on carpeting.
C. Provide clearance between boiler jacket and
combustible material in accordance with local re
ordinance. Refer to Figure 4 for minimum listed
clearances from combustible material. Recommended
service clearance is 24 in. (610 mm) from left side,
front, top and rear of the boiler. Recommended front
clearance may be reduced to the combustible material
clearance providing:
1. Access to boiler front is provided through a door or
removable front access panel.
2. Access is provided to the condensate trap located
underneath the heat exchanger.
3. Access is provided to thermal link located at boiler
rear.
D. Protect gas ignition system components
from water (dripping, spraying, rain, etc.) during
boiler operation and service (circulator replacement,
condensate trap, control replacement, etc.).
E. Provide combustion and ventilation air in
accordance with applicable provisions of local building
codes, or: USA - National Fuel Gas Code, ANSI
Z223.1/NFPA 54, Air for Combustion and Ventilation;
Canada - Natural Gas and Propane Installation Code,
CAN/CSA-B149.1, Venting Systems and Air Supply for
Appliances.
Contaminants to avoid:
Spray cans containing chloro/uorocarbons (CFC’s)
Permanent wave solutions
Chlorinated waxes/cleaners
Chlorine-based swimming pool chemicals
Calcium chloride used for thawing
Sodium chloride used for water softening
Refrigerant leaks
Paint or varnish removers
Hydrochloric acid/muriatic acid
Cements and glues
Antistatic fabric softeners used in clothes dryers
Chlorine-type bleaches, detergents, and cleaning solvents found
in household laundry rooms.
Adhesives used to fasten building products and other similar
products
Excessive dust and dirt
Areas likely to have contaminants:
Dry cleaning/laundry areas and establishments
Swimming pools
Metal fabrication plants
Beauty shops
Refrigeration repair shops
Photo processing plants
Auto body shops
Plastic manufacturing plants
Furniture renishing areas and establishments
New building construction
Remodeling areas
Garages with workshops
Table 4: Corrosive Combustion Air Contaminants
and Sources
III. Pre-Installation and Boiler Mounting

11
III. Pre-Installation and Boiler Mounting (continued)
WARNING
Asphyxiation Hazard. Adequate combustion and
ventilation air must be provided to assure proper
combustion. Install combustion air intake per
Section IV “Venting”.
F. The boiler should be located so as to minimize
the length of the vent system. Locate combustion air
pipe termination away from areas that may contaminate
combustion air, (see Table 4). In particular, avoid
areas near chemical products containing chlorines,
chlorouorocarbons, paint removers, cleaning solvents
and detergents. Avoid areas containing saw dust, loose
insulation bers, dry wall dust etc.
NOTICE
Avoid operating this boiler in an environment
where sawdust, loose insulation bers, dry wall
dust, etc. are present. If boiler is operated under
these conditions, the burner interior and ports
must be cleaned and inspected daily to insure
proper operation.
G. General.
1. Alpine boilers are intended for installations in an
area with a oor drain, or in a suitable drain pan to
prevent any leaks or safety relief valve discharge
resulting in property damage.
2. Alpine boilers are not intended to support external
piping and venting. All external piping and venting
must be supported independently of the boiler.
3. Alpine boilers must be installed level to prevent
condensate from backing up inside the boiler.
4. Boiler Installation:
a. For basement installation provide a solid level
base such as concrete where oor is not level or
where water may be encountered on the oor
around boiler. Floor must be able to support
Table 5: Vent Pipe Clearances to Combustible Material
Boiler Clearances to Combustible (and Non-
Combustible) Material:
Models ALP399C and ALP500C:
These boilers are listed for closet installation with the
following minimum clearances – Top = 1 in. (25 mm),
Front = 1 in. (25 mm), Left Side = 10 in. (250 mm),
Right Side = 2 in. (50 mm), Rear = *6 in. (150 mm)
Models ALP600C, ALP700C and ALP800C:
These boilers are listed for alcove installation with the
following minimum clearances – Top = 1 in. (25 mm),
Front = Open, Left Side = 10 in. (250 mm), Right Side
= 2 in. (50 mm), Rear = *6 in. (150 mm)
* Note:
When boiler is vented vertically, the minimum
clearance from the rear of the jacket is increased to
18 in. (460 mm) with a short radius 90° elbow
provided in order to provide adequate space at boiler
rear for installation of vent and air intake piping and
service access.
Boiler Service Clearances – Applicable to all Boiler
Models:
Top = 24 in. (610 mm), Front = 24 in. (610 mm), Left
Side = 24 in. (610 mm), Right Side = 24 in. (610 mm),
Rear = 24 in. (610 mm)
The above clearances are recommended for service
access but may be reduced to the Combustible Material
Clearances provided:
1. The boiler front is accessible through a door.
2. Access is provided to the condensate trap located on
the left side of boiler.
3. Access is provided to thermal link located at the
boiler rear.
Listed Direct
Vent System Vent Pipe Material Vent Pipe Direction Enclosure Vent Pipe Nominal Diameter
Minimum
Clearance to
Combustible
Material
Standard
Two-Pipe CPVC/PVC Vent and PVC Combustion Air Intake CPVC/PVC
Vertical or
Horizontal
Unenclosed
at all Sides
3 in. (80 mm),
4 in. (100 mm or 110 mm),
6 in.( 150 mm or 160 mm)
1 in. (25 mm)
Optional
Two-Pipe Rigid Polypropylene Vent (or, Flexible Polypropylene
Liner for Vertical Venting only) and Rigid Polypropylene or PVC
Combustion Air Intake
Rigid Polypropylene (or,
Flexible Polypropylene
Liner for Vertical Venting
only)
3 in. (80 mm),
4 in. (100 mm or 110 mm),
6 in.( 150 mm or 160 mm)
1 in. (25 mm)
Optional
Two-Pipe Stainless Steel Vent and Galvanized Steel or PVC
Combustion Air Intake
Stainless Steel
3 in. (80 mm),
4 in. (100 mm or 110 mm),
6 in.( 150 mm or 160 mm)
1 in. (25 mm)
weight of boiler, water and all additional system
components.
b. Boiler must be level to prevent condensate from
backing up inside the boiler.
c. Provide adequate space for condensate piping or
a condensate pump if required.

12
III. Pre-Installation and Boiler Mounting (continued)
H. Boiler Stacking
1. For installations with unusually high space heating
and/or domestic hot water heating loads, where
employing multiple boilers will offer the benets of
greater operational efciency, oor space savings
and boiler redundancy, boilers may be installed
stacked maximum one boiler on top of another.
Refer to Table 6 “Alpine Boiler Model Stacking
Combinations” for details.
Table 6: Alpine Boiler Model Stacking
Combinations
Bottom
Boiler Model Top Boiler Model
ALP399C ALP399C
ALP500C ALP399C or ALP500C
ALP600C ALP399C, ALP500C or ALP600C
ALP700C ALP399C, ALP500C, ALP600C or ALP700C
ALP800C ALP399C, ALP500C, ALP600C, ALP700C or
ALP800C
2. To eld assemble individual Alpine boilers into a
stackable conguration, use the steps below:
a. Position the bottom boiler rst. Refer to Sections
II “Unpacking Boiler” and III “Pre-Installation
& Boiler Mounting” of the manual for details.
Always position higher input boiler model as
bottom boiler.
b. Each Alpine boiler is factory packaged with
2 stacking boiler attachment brackets (P/N
101679-01) and the bracket mounting hardware
[six (6) self-drilling hex washer head plated #8
x ½” long screws, P/N 80860743]. Locate and
remove the brackets and the hardware. The
stacking boiler attachment bracket has three
7/32” diameter holes punched in a triangular
pattern. See Figure 5 “Boiler Stacking”.
c. Alpine boiler left and right side panels have a
series of dimples at panel top and bottom. These
dimples are positioning dimples for stacking
boiler attachment bracket mounting screws. Side
panel bottom positioning dimples are evenly
spaced from boiler front and back, while side
panel top positioning dimples follow specic
pattern to compensate for Alpine boiler model
variable depth.
d. Position the upper boiler on top of the bottom
boiler and align boiler front doors and sides ush
with each other.
• Place rst stacking boiler attachment bracket
onto the upper boiler left side panel, at the
panel lower left corner and align bracket two
upper holes with corresponding side panel
lower dimples.
Figure 4: Clearances To Combustible and Non-combustible Material

13
III. Pre-Installation and Boiler Mounting H. Boiler Stacking (continued)
• The remaining lower bracket hole must align
with a matching bottom boiler left side panel
top positioning dimple.
• Once bracket holes and side panel dimple
alignment is veried, attach the bracket to
top and bottom boiler left side panels with
the mounting screws.
e. Repeat above procedure to install second
stacking boiler attachment bracket and secure the
stacked boiler right side panels together at the
front right corner.
f. Install the third stacking boiler attachment
bracket to secure top and bottom boiler left side
panels at the rear left corner. Align the bracket
holes with corresponding positioning dimples in
the top boiler and bottom boiler left side panels,
then secure bracket with the screws.
g. Repeat above procedure to install the fourth
stacking boiler attachment bracket to secure
stacked boiler right side panels at the rear right
corner.
3. When installing stackable boiler combinations
observe the following guidelines:
a. Venting - Top and bottom boilers must have their
individual vent piping and vent terminals.
WARNING
Asphyxiation Hazard. No common manifold
venting is permitted. Each boiler must have its
own individual vent and combustion air pipes
and terminals.
For sidewall venting individual model vent
terminals must terminate no closer than 12
in. (300 mm) horizontally and 3 ft. (900 mm)
vertically from each other in order to prevent
combustion air contamination. For vertical
through the roof venting, individual vertical
vent terminals, if level with each other, must
be spaced no closer than 12 in. (300 mm)
horizontally. If vertical terminals cannot end in
one plane, they must be spaced no closer than 3
ft. (900 mm) horizontally.
Follow instructions in Section IV “Venting”
of the manual for specics of individual boiler
vent termination. Follow instructions in Section
V “Condensate Disposal” for each individual
boiler ue gas condensate line construction and
condensate disposal. Terminating individual
boiler condensate lines into common pipe prior
to drain disposal is permissible, providing
common pipe has sufcient ow capacity
to handle combined condensate volume of
stackable combination.
b. Gas Piping - Follow instructions in Section
VII “Gas Piping” of the manual for sizing
and installation of an individual boiler. When
common gas piping is sized, insure it will
have adequate capacity for combined input
(CFH gas ow) of the selected stackable boiler
combination.
c. Water Piping and Trim - Follow instructions
in Section VI “Water Piping and Trim” of the
manual for system piping and boiler secondary
piping selection/sizing based on combined
heating capacity and/or gross output of the
selected stackable boiler combination. Follow
instructions of Section VI “Water Piping
and Trim” for each individual boiler trim
installation.
d. Electrical - Follow instructions in Section VIII
“Electrical” of the manual to wire individual
boilers.

14
III. Pre-Installation and Boiler Mounting H. Boiler Stacking (continued)
Figure 5: Boiler Stacking

15
IV. Venting
WARNING
Asphyxiation Hazard. Failure to vent this boiler in accordance with these instructions could cause
products of combustion to enter the building resulting in severe property damage, personal injury or
death.
Do not use a barometric damper, draft hood or vent damper with this boiler.
Do not locate vent termination under a deck.
Do not locate vent termination where exposed to prevailing winds.
Do not locate combustion air termination where chlorines, chlorouorocarbons (CFC’s), petroleum
distillates, detergents, volatile vapors or other chemicals are present. Severe boiler corrosion and
failure will result.
Use specied vent and combustion air pipe diameters.
Do not interchange vent systems or materials unless otherwise specied.
Do not apply thermal insulation to vent pipe or ttings.
Moisture and ice may form on surface around vent termination. To prevent deterioration, surface must
be in good repair (sealed, painted, etc.).
Do not allow low spots in the vent where condensate may pool.
The CPVC vent materials supplied with this boiler do not comply with Natural Gas and Propane
Installation Code, CAN/CSA B149.1.S1-07 and are not approved for use in Canadian jurisdictions that
require vent systems be listed to ULC S636-2008. In these jurisdictions, vent this boiler using either
stainless steel Special Gas vent or a listed ULC S636 Class IIB venting system.
A. General Guidelines
1. Listed Vent/Combustion Air Systems
a. Install vent system in accordance with National
Fuel Gas Code, ANSI Z223.1/NFPA 54 or
Natural Gas and Propane Installation Code,
CAN/CSA B149.1 Installation Code for Canada,
or, applicable provisions of local building codes.
Contact local building or re ofcials about
restrictions and installation inspection in your
area.
b. The Alpine may be installed as a direct vent/
sealed combustion boiler or with optional room
air for combustion. Direct vent is recommended
for residential applications. For direct vent,
pipe combustion air from the outdoors directly
to the boiler cabinet. Room air is optional for
commercial applications. For room air, provide
combustion and ventilation air per the National
Fuel Gas Code, ANSI Z223.1, or, in Canada,
Installation Code for Gas Burning Appliances
and Equipment, CGA Standard B149.
c. The following combustion air/vent system
options are listed for use with the Alpine boilers
(refer to Table 7):
i. Two-Pipe CPVC/PVC Vent/Combustion
Air System - Separate CPVC/PVC pipe
serves to expel products of combustion and
separate PVC pipe delivers fresh outdoor
combustion air. Refer to Part B for specic
details.
ii. Two-Pipe Polypropylene Vent/
Combustion Air System - Separate rigid or
exible polypropylene pipe serves to expel
products of combustion and separate rigid
polypropylene or PVC pipe delivers fresh
outdoor combustion air. Refer to Part C for
specic details.
iii. Two-Pipe Stainless Steel Vent/Combustion
Air System - Separate stainless steel pipe
serves to expel products of combustion
and separate PVC or galvanized steel pipe
delivers fresh outdoor combustion air. Refer
to Part D for specic details.
iv. Room Air for Combustion – CPVC/
PVC, polypropylene, or stainless steel pipe
serves to expel products of combustion and
combustion air is supplied from the boiler
room. Refer to Part E for specic details.
2. Vent/Combustion Air Piping
a. Do not exceed maximum vent/combustion air
lengths listed in Table 8. Vent/combustion
air length restrictions are based on equivalent
length of vent/combustion air pipe (total
length of straight pipe plus equivalent length
of ttings). Table 9 lists equivalent lengths for
ttings. Do not include vent/combustion air
terminals in equivalent feet calculations. Use
vent/combustion air equivalent length worksheet
provided in Table 10.

16
Table 7: Vent/Combustion Air Intake System Options
IV. Venting A. General Guidelines (continued)
Vent & Intake
Materials Option
Penetration
Through
Structure
Termination Figures Component
Table
Reference
Section
Standard CPVC/PVC Two-Pipe,
CPVC/PVC
Vent and PVC Air Intake
1
Intake Horizontal Sidewall 90° Elbow w/ Screen
7, 8 11, 12
A, B
Vent Horizontal Sidewall Coupling w/ Screen
2Intake Horizontal Sidewall Ipex Low Prole 9 13
Vent Horizontal Sidewall
3Intake Horizontal Sidewall 90° Elbow w/ Screen 7, 8, 10 not provided
Vent Vertical Roof Coupling w/ Screen
4
Intake Vertical Roof (2) 90° Elbows w/ Screen
10 14
Vent Vertical Roof Coupling w/ Screen
5
Intake N/A - Room Air
7, 8 not provided
A, B, E
Vent Horizontal Sidewall 90° Elbow or Tee w/ Screen
6
Intake N/A - Room Air
10 not provided
Vent Vertical Roof Coupling w/ Screen
Optional Polypropylene
Two-pipe, Rigid PP
Vent or Flexible PP
Vent (Vertical Only) and Rigid PP
or PVC Air Intake
7
Intake Horizontal Sidewall UV Resistant 90° Elbow
w/Screen 7, 8 17, 18
A,C
Vent Horizontal Sidewall UV Resistant Straight Pipe
w/Screen
8Intake Horizontal Sidewall Ipex Low Prole 9 13, 17, 18
Vent Horizontal Sidewall
9
Intake Horizontal Sidewall UV Resistant 90° Elbow
w/Screen 7, 8, 10 17, 18
Vent Vertical Roof UV Resistant Straight Pipe
w/Screen
10
Intake Vertical Roof (2) UV Resistant 90° Elbows
w/Screen 10 17, 18
Vent Vertical Roof UV Resistant Straight Pipe
w/Screen
11
Intake N/A - Room Air
7, 8 17, 18
A,C, E
Vent Horizontal Sidewall UV Resistant 90° Elbow
w/Screen
12
Intake N/A - Room Air
10 17, 18
Vent Vertical Roof UV Resistant Straight Pipe
w/Screen
Optional Stainless Steel
Two-pipe, SS Vent and
Galvanized Steel or PVC
Air Intake
13
Intake Horizontal Sidewall 90° Elbow w/Screen
7, 8 19, 20, 21
A, D
Vent Horizontal Sidewall Straight Termination
w/Screen
14
Intake Horizontal Sidewall 90° Elbow w/Screen
7, 8, 10 19, 20, 21
Vent Vertical Roof Straight Termination
w/Screen
15
Intake Vertical Roof (2) 90° Elbows w/Screen
10 19, 20, 21
Vent Vertical Roof Straight Termination
w/Screen
16 Intake N/A - Room Air 7, 8 19, 20, 21
A, D, E
Vent Horizontal Sidewall 90° Elbow or Tee w/Screen
17 Intake N/A - Room Air 10 19, 20, 21
Vent Vertical Roof 90° Elbow or Tee w/Screen

17
IV. Venting A. General Guidelines (continued)
Table 8: Vent and Combustion Air Pipe Sizes and Equivalent Lengths
(Applies to All Listed Vent/Combustion Air System Options)
Boiler
Model Option
Combustion Air Length Vent Length Approx. Derate at
Max. Length
(%)
Pipe Dia., in.
(mm)
Min., ft.
(m)
Max., ft.
(m)
Pipe Dia., in.
(mm)
Min., ft.
(m)
Max., ft.
(m)
ALP399C
Standard
Diameter 4 (100 or 110) 0100 (30.5) 4 (100 or 110) 2.5 (760) 100 (30.5) 5
Reduced
Diameter 3 (80) 050 (15.2) 3 (80) 2.5 (760 ) 50 (15.2 ) 5
ALP500C
Standard
Diameter 4 (100 or 110) 0100 (30.5) 4 (100 or 110) 2.5 (760) 100 (30.5) 11
Reduced
Diameter 3 (80) 050 (15.2) 3 (80) 2.5 (760) 50 (15.2 ) 12
ALP600C
Standard
Diameter 4 (100 or 110) 0100 (30.5) 6 (150 or 160) 2.5 (760) 200 (30.5) 7
Reduced
Diameter 4 (100 or 110) 050 (15.2) 4 (100 or 110) 2.5 (760) 50 (15.2 ) 10
ALP700C
Standard
Diameter 4 (100 or 110) 0100 (30.5) 6 (150 or 160) 2.5 (760) 200 (30.5) 11
Reduced
Diameter 4 (100 or 110) 050 (15.2) 4 (100 or 110) 2.5 (760) 50 (15.2 ) 15
ALP800C
Standard
Diameter 4 (100 or 110) 0100 (30.5) 6 (150 or 160) 2.5 (760) 200 (30.5) 14
Reduced
Diameter 4 (100 or 110) 050 (15.2) 4 (100 or 110) 2.5 (760) 50 (15.2 ) 15
Component Equivalent Length
Nominal Diameter 3 in. (80 mm) 4 in. (100 or 110 mm) 6 in. (150 or 160 mm)
90° Elbow, Short Radius 10 ft. (3.0 m) 13 ft. (4.0 m) 22 ft. (6.7 m)
90° Elbow, Long Sweep/Sanitary 4.0 ft. (1.2 m) 9 ft. (2.7 m) 17 ft. (5.2 m)
45° Elbow 3.0 ft. (0.9 m) 4.5 ft. (1.4 m) 7.5 ft. (2.3 m)
Table 9: Vent System and Combustion Air System Component Equivalent Length
(Applies to All Listed Vent/Combustion Air System Options)
Table 10: Vent and Combustion Air Equivalent Length Calculation Worksheet
Component
Combustion Air Vent
Equivalent
Length Per
Piece
x Quantity = Subtotal
Equivalent Length
Equivalent
Length Per
Piece
x Quantity = Subtotal Equivalent
Length
Straight Pipe x = A E
90° Elbow,
Short Radius x= B F
90° Elbow,
Long Sweep/
Sanitary
x= C G
45° Elbow x = D H
Combustion Air Total
Equivalent Length
= A+B+C+D Vent Total
Equivalent Length
= E+F+G+H
Notes:
1. Total equivalent length cannot exceed maximum equivalent length shown in Table 8.
2. Use elbow equivalent lengths provided in Table 9.
3. Combustion air and vent terminations do not count towards total equivalent length.
4. Pressure drop for exible polypropylene liner is 20% greater than for rigid pipe. Multiply measured exible polypropylene liner
length by 1.2 to obtain equivalent length.
Example
Measured length = 35 ft.
Equivalent length =35 ft. x 1.2 = 42 ft.
5. Maximum equivalent length of exible polypropylene liner is 48 ft. (14.6 m).

18
IV. Venting A. General Guidelines (continued)
Figure 6: Location of Vent Terminal Relative to Windows, Doors, Grades, Overhangs, Meters and Forced Air Inlets -
Two-Pipe System Vent Terminal (Shown), Two-Pipe System Air Intake Terminal (Not Shown)

19
IV. Venting A. General Guidelines (continued)
b. Maintain minimum clearance to combustible
materials. See Table 5 for details.
c. Enclose vent passing through occupied or
unoccupied spaces above boiler with material
having a re resistance rating at least equal to the
rating of adjoining oor or ceiling.
Note: For one or two family dwellings, re
resistance rating requirement may not need to be
met, but is recommended.
d. Slope horizontal vent pipe minimum 1/4 in/ft
(21 mm/m) downward towards the boiler.
Les chaudières de catégories I, II et IV doivent
présenter des tronçons horizontaux dont la pente
montante est d’au moins 1/4 po par pied (21
mm/m) entre la chaudière et l’évent.
e. If possible, slope horizontal combustion air
pipe minimum 1/4 in/ft (21 mm/m) downward
towards terminal. If not, slope towards boiler.
f. Use noncombustible ¾ in. pipe strap to support
horizontal runs and maintain vent location and
slope while preventing sags in pipe. Do not
restrict thermal expansion or movement of vent
system. Maximum support spacing 4 ft. (1.2 m).
Avoid low spots where condensate may pool.
Do not penetrate any part of the vent system with
fasteners.
Les instructions d´installation du système
d´évacuation doivent préciser que les sections
horizontales doivent être supportées pour
prévenir le échissement. Les méthodes et les
Figure 7: Direct Vent - Sidewall Standard Terminations
intervalles de support doivent être spéciés.
Les instructions divent aussi indiquer les
renseignements suivants:
les chaudières de catégories II et IV doivent être
installées de façon à empêcher l´accumulation de
condensat: et
si nécessaire, les chaudières de catégories II et IV
doivent être pourvues de dispositifs d´évacuation
du condensat.
g. For multiple boiler installations with vertical
roof terminals, separate vent pipes from multiple
boilers may be piped through a common conduit
or chase so that one roof penetration may be
made.
3. Vent/Combustion Air Terminals
Install venting system components on exterior
of building only as specically required by these
instructions (refer to Figure 6).
a. Use only listed vent/combustion air terminals.
i. Horizontal Sidewall Venting: Use coupling
for vent and 90° elbow pointed down for
combustion air as shown in Figure 7 or
Figure 8. If using room air for combustion,
use 90° elbow or tee for vent. Alternate low
prole termination is shown in Figure 9.

20
IV. Venting A. General Guidelines (continued)
Figure 8: Direct Vent - Sidewall Snorkel Terminations
Figure 9: Direct Vent - Sidewall Low Prole Termination
ii. Vertical Roof Venting: Use coupling on vent
and two 90° elbows turned downwards for
combustion air as shown in Figure 10 and
Figure 11.
b. Maintain correct clearance and orientation
between vent and combustion air terminals.
i. Space center lines of vent and combustion
air terminals minimum 12 in. (300
mm) apart. 36 in. (915 mm) spacing is
recommended.
ii. If possible, locate vent and combustion
air terminals on the same wall to prevent
nuisance shutdowns. If not, boiler may
be installed with roof vent terminal and
sidewall combustion air terminal.
iii. When installed on the same wall, locate
vent terminal at same height or higher than
combustion air terminal.
c. Locate bottom of vent and combustion air
terminals at least 12 in. (300 mm) [18 in.
(460 mm) in Canada] above the normal snow line
and at least 12 in. (300 mm) above grade level.
d. Locate vent and combustion air terminals at
least 12 in. (300 mm) from any door, window, or
gravity inlet into the building.
e. Do not install vent terminal directly above
windows or doors.