Ace Heating Solutions Atlas A050 Operating instructions

Operating and Maintenance Manual
Designed and Manufactured in Accordance with
ASME Code Section IV Heating Boilers
Photo shown may vary from actual model.
Copper-Fin Coil
High Efficiency
Condensing Boiler /
Water Heater
Models A050-A300
E.T.L. Listed
E.T.L.
Canadian
Listed
c
HLW
U.L. 795
CSA 3.1
H

2
Rev 2.1
Table of Contents
Description Page #
1 Introduction.......................................................................................................................................................... 8
1-1 Pre-Installation ............................................................................................................................................. 9
1-2 Boiler Nameplate and Model Number ....................................................................................................... 10
1-3 Rating and Certifications............................................................................................................................ 11
1-4 Connection Information.............................................................................................................................. 11
1-5 General Safety ............................................................................................................................................ 11
2 Installation.......................................................................................................................................................... 13
2-1 Installation Codes ....................................................................................................................................... 13
2-2 Equipment Base.......................................................................................................................................... 13
2-3 Determining Unit Location......................................................................................................................... 13
2-4 Combustion and Ventilation Air ................................................................................................................ 14
2-5 Conventional Combustion Air Supply ....................................................................................................... 16
2-6 Conventional Exhaust Venting................................................................................................................... 17
2-7 Gas Supply.................................................................................................................................................. 20
2-8 Pump Installation........................................................................................................................................ 22
2-9 Electrical Connections................................................................................................................................ 23
2-10 DHW/CH Installation and Programming ................................................................................................. 25
2-10.1 Domestic Hot Water Mode................................................................................................................ 25
2-10.2 Central Heating Mode ....................................................................................................................... 25
2-10.3 4–20 mA Remote Setpoint .............................................................................................................. 26
2-11 Lead Lag Installation and Programming .................................................................................................. 26
2-11.1 Sensor Wiring .................................................................................................................................... 26
2-12 Lead Lag Operation.................................................................................................................................. 26
2-12.1 Sequencing......................................................................................................................................... 26
2-12.2 Rate Allocation Control..................................................................................................................... 26
2-12.3 Add Stage Method ............................................................................................................................. 27
2-12.4 Drop Stage Method............................................................................................................................ 27
2-13 System Integrator Display Wiring and Lead Lag Bus Wiring ................................................................. 27
2-13.1 System Integrator Display Wiring..................................................................................................... 27
2-13.2 Modbus Address Programming ......................................................................................................... 29
2-13.3 Lead Lag Bus Wiring......................................................................................................................... 29
2-13.4 Enable Lead Lag Master.................................................................................................................... 29
2-13.5 Enable Lead Lag Master Using Basic Panel...................................................................................... 29
2-13.6 Enable Lead Lag Master Using Enhanced or System Operator Interface Panel ............................... 29
2-13.7 Enable Lead Lag Slave ...................................................................................................................... 29
2-13.8 Enable Lead Lag Slave Using Basic Panel........................................................................................ 29
2-13.9 Enable Lead Lag Slave Using Enhanced or System Operator Interface Panel ................................. 29
2-14 Suggested Piping ...................................................................................................................................... 30
2-14.1 Suggested Domestic Hot Water Piping Diagrams............................................................................. 30
2-14.2 Suggested Central Heating Piping Diagrams .................................................................................... 35
3 Basic Panel Operating Procedures ..................................................................................................................... 37
3-1 Introduction ................................................................................................................................................ 37
3-2 Basic Panel Description.............................................................................................................................. 37
3-3 Operation .................................................................................................................................................... 37
3-4 User Mode .................................................................................................................................................. 38
3-5 Setup Mode................................................................................................................................................. 39

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Rev 2.1
3-6 Diagnostic Mode ........................................................................................................................................ 41
3-7 Error Mode ................................................................................................................................................. 42
3-8 Honeywell Sola Controller Start Sequence ................................................................................................ 43
3-9 Start/Stop Levels ........................................................................................................................................ 44
3-10 High Limit Setpoint.................................................................................................................................. 44
4 Enhanced/System Operator Interface Panel Operating Procedures................................................................... 45
4-1 Introduction ................................................................................................................................................ 45
4-2 Enhanced Panel And System Operator Interface Panel Description.......................................................... 45
4-3 Operation .................................................................................................................................................... 45
4-4 System Operator Interface Panel Home Page ............................................................................................ 46
4-5 Page Navigation.......................................................................................................................................... 46
4-6 Keyboard .................................................................................................................................................... 46
4-7 Status Page.................................................................................................................................................. 47
4-8 Configuration Page..................................................................................................................................... 47
4-9 Configuration Password ............................................................................................................................. 48
4-10 Change Parameter Settings....................................................................................................................... 49
4-11 Fault/Alarm Handling............................................................................................................................... 51
4-12 History Page ............................................................................................................................................. 52
4-13 Operation Page ......................................................................................................................................... 53
4-14 Diagnostic Page ........................................................................................................................................ 53
4-15 Trend Analysis Page................................................................................................................................. 54
4-16 Configuration............................................................................................................................................ 54
4-17 System Identification & Access Parameters............................................................................................. 54
4-18 Central Heating Parameters...................................................................................................................... 55
4-19 Outdoor Reset Parameters ........................................................................................................................ 55
4-20 DHW Configuration Parameters .............................................................................................................. 56
4-21 Modulation Configuration Parameters ..................................................................................................... 57
4-22 Pump Configuration Parameters............................................................................................................... 57
4-23 Statistics Configuration Parameters ......................................................................................................... 58
4-24 High Limit Configuration Parameters...................................................................................................... 58
4-25 Stack Limit Configuration Parameters ..................................................................................................... 59
4-26 Other Limit Configuration Parameters..................................................................................................... 59
4-27 Frost Protection Configuration Parameters .............................................................................................. 60
4-28 DHW Storage Configuration Parameters ................................................................................................. 60
4-29 Warm Weather Shutdown Configuration Parameters .............................................................................. 60
4-30 T-Rise Limit Configuration Parameters ................................................................................................... 61
4-31 Lead Lag Slave Configuration Parameters............................................................................................... 61
4-32 Lead Lag Master Configuration Parameters............................................................................................. 62
4-33 Lead Lag Master Configuration Parameters Advanced Settings ............................................................. 62
4-34 Monitoring................................................................................................................................................ 64
4-35 Trend Analysis Page................................................................................................................................. 65
4-36 Honeywell Sola Controller Diagnostics ................................................................................................... 66
4-37 Installer Checkouts – Diagnostics Tests................................................................................................... 67
4-38 System Time............................................................................................................................................. 67
5 Installer Integration Guide ................................................................................................................................. 69
5-1 Central Heat Related Configuration ........................................................................................................... 69
5-1.1 To Enable or Disable CH Loop ........................................................................................................... 69
5-1.2 To Change CH Loop Demand Switch................................................................................................. 69
5-1.3 To Select CH Modulation Sensor........................................................................................................ 69
5-1.4 To Change CH Loop Setpoint ............................................................................................................. 69

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Rev 2.1
5-1.5 To Change CH Loop Time Of Day Setpoint....................................................................................... 69
5-1.6 To Change CH Loop Off Hysteresis ................................................................................................... 69
5-1.7 To Change CH Loop On Hysteresis .................................................................................................... 69
5-1.8 To Change CH Loop Hysteresis Step Time ........................................................................................ 70
5-1.9 To Enable Or Disable CH Loop Outdoor Reset .................................................................................. 70
5-1.10 To Change CH loop P-I-D parameters .............................................................................................. 70
5-1.11 To Change CH Loop Setpoint Source ............................................................................................... 71
5-1.12 To Change CH 4-20ma Setpoint Range ............................................................................................ 71
5-1.13 To Change CH Priority Over Lead Lag............................................................................................. 71
5-2 Outdoor Reset Related Configuration ........................................................................................................ 71
5-2.1 To Change Maximum Outdoor Temperature ...................................................................................... 71
5-2.2 To Change Minimum Outdoor Temperature....................................................................................... 71
5-2.3 To Change Minimum Water Temperature .......................................................................................... 71
5-2.4 Outdoor Reset Graph ........................................................................................................................... 71
5-2.5 To Change Low Water Temperature ................................................................................................... 72
5-2.6 To Change Maximum Off Point.......................................................................................................... 72
5-3 Domestic Hot Water Related Configuration .............................................................................................. 72
5-3.1 To Enable Or Disable DHW Loop ...................................................................................................... 72
5-3.2 To Change DHW Loop Demand Switch............................................................................................. 72
5-3.3 To Change DHW Loop Priority Versus CH Loop .............................................................................. 73
5-3.4 To Change DHW Loop Priority Time................................................................................................. 73
5-3.5 To Change DHW Loop Setpoint ......................................................................................................... 73
5-3.6 To Change DHW Loop Time Of Day Setpoint................................................................................... 73
5-3.7 To Change DHW Loop Off Hysteresis ............................................................................................... 73
5-3.8 To Change DHW Loop On Hysteresis ................................................................................................ 73
5-3.9 To Change The DHW Hysteresis Step Time....................................................................................... 73
5-3.10 To Change DHW Loop P-I-D Parameters......................................................................................... 74
5-3.11 To Change DHW Modulation Sensor................................................................................................ 74
5-3.12 To Change DHW Loop Priority Versus LL ...................................................................................... 74
5-4 Modulation Related Configuration............................................................................................................. 74
5-4.1 To Change CH Loop Maximum Modulation Rate.............................................................................. 74
5-4.2 To Change DHW Loop Maximum Modulation Rate.......................................................................... 74
5-4.3 To Change CH Loop Forced Rate Time.............................................................................................. 74
5-4.4 To Change CH Loop Forced Rate ....................................................................................................... 74
5-4.5 To Change DHW Loop Forced Rate Time.......................................................................................... 75
5-4.6 To Change DHW Forced Rate............................................................................................................. 75
5-4.7 To Enable Or Disable CH Loop Slow Start ........................................................................................ 75
5-4.8 To Enable Or Disable DHW Loop Slow Start .................................................................................... 75
5-4.9 To Change Slow Start Degrees............................................................................................................ 75
5-4.10 To Change Slow Start Ramp ............................................................................................................. 75
5-5 Pump Control Related Configuration......................................................................................................... 75
5-5.1 To Set CH Loop Pump Control On Or Auto ....................................................................................... 75
5-5.2 To Change CH Loop Pump Overrun Time ......................................................................................... 75
5-5.3 To Set DHW Loop Pump Control On Or Auto ................................................................................... 76
5-5.4 To Change DHW Loop Pump Overrun Time...................................................................................... 76
5-5.5 To Set System Loop Pump Control On Or Auto................................................................................. 76
5-5.6 To Change System Loop Pump Overrun Time ................................................................................... 76
5-5.7 To Change System Pump Exercise Interval ........................................................................................ 76
5-5.8 To Change System Pump Exercise Time ............................................................................................ 76
5-6 High Limit Related Configuration.............................................................................................................. 76

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Rev 2.1
5-6.1 To Enable Or Disable DHW High Limit............................................................................................. 76
5-6.2 To Change DHW High Limit Setpoint................................................................................................ 77
5-6.3 To Change Outlet High Limit Setpoint ............................................................................................... 77
5-6.4 To Change DHW High Limit Response.............................................................................................. 77
5-7 Stack Limit Related Configuration............................................................................................................. 77
5-7.1 To Enable Or Disable Stack Limit ...................................................................................................... 77
5-7.2 To Change Stack Limit Delay ............................................................................................................. 77
5-7.3 To Change Stack Limit Response ....................................................................................................... 77
5-7.4 To Change Stack Limit Setpoint ......................................................................................................... 77
5-8 Delta-T Limit Related Configuration ......................................................................................................... 78
5-8.1 To Enable Or Disable Delta-T Limit................................................................................................... 78
5-8.2 To Change Delta-T Limit Delay.......................................................................................................... 78
5-8.3 To Change Delta-T Limit Response.................................................................................................... 78
5-8.4 To Change Delta-T Limit Degrees ...................................................................................................... 78
5-8.5 To Change Delta-T Retry Limit .......................................................................................................... 78
5-8.6 To Enable Delta-T Rate Limit ............................................................................................................. 78
5-8.7 To Change Delta-T Inverse Limit Time .............................................................................................. 78
5-8.8 To Change Delta-T Inverse Limit Response ....................................................................................... 78
5-9 Frost Protection Related Configuration...................................................................................................... 79
5-9.1 To Enable Or Disable CH Loop Frost Protection................................................................................ 79
5-9.2 To Enable Or Disable DHW Loop Frost Protection............................................................................ 79
5-9.3 To Change Outdoor Frost Protection Setpoint .................................................................................... 79
5-9.4 To Enable Or Disable Ll Frost Protection ........................................................................................... 79
5-9.5 To Change LL Frost Protection Rate................................................................................................... 79
5-9.6 To Change CH Loop Pump Frost Protection Overrun Time............................................................... 79
5-9.7 To Change DHW Loop Pump Frost Protection Overrun Time........................................................... 79
5-10 DHW Storage Configuration.................................................................................................................... 80
5-10.1 To Enable DHW Storage Mode......................................................................................................... 80
5-10.2 To Change DHW Storage Time ........................................................................................................ 80
5-10.3 To Change DHW Storage Setpoint.................................................................................................... 80
5-10.4 To Change DHW Storage On Hysteresis .......................................................................................... 80
5-10.5 To Change DHW Storage Off Hysteresis.......................................................................................... 80
5-11 Warm Weather Shutdown Configuration................................................................................................. 80
5-11.1 To Enable Wwsd ............................................................................................................................... 80
5-11.2 To Change Wwsd Setpoint ................................................................................................................ 80
5-12 T-Rise Limit Configuration...................................................................................................................... 80
5-12.1 To Enable Outlet T-Rise.................................................................................................................... 80
5-12.2 To Change T-Rise Degree ................................................................................................................. 81
5-12.3 To Change T-Rise Response ............................................................................................................. 81
5-12.4 To Change T-Rise Retry Limit.......................................................................................................... 81
5-12.5 To Change T-Rise Limit Delay ......................................................................................................... 81
5-13 Lead Lag Slave Configuration.................................................................................................................. 81
5-13.1 To Enable Lead Lag Slave................................................................................................................. 81
5-13.2 To Change Lead Lag Slave Mode ..................................................................................................... 81
5-13.3 To Change Base Load Rate ............................................................................................................... 81
5-13.4 To Change Slave Sequence Order ..................................................................................................... 81
5-13.5 To Change Demand To Firing Delay ................................................................................................ 82
5-13.6 To Change Modbus Port.................................................................................................................... 82
5-13.7 To Change Modbus Address ............................................................................................................. 82
5-14 Lead Lag Master Configuration ............................................................................................................... 82

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Rev 2.1
5-14.1 To Enable Lead Lag Master .............................................................................................................. 82
5-14.2 To Change Lead Lag CH Setpoint..................................................................................................... 82
5-14.3 To Change Lead Lag CH TOD Setpoint ........................................................................................... 82
5-14.4 To Change Modbus Port.................................................................................................................... 82
5-15 Lead Lag Advanced Setting: Modulation Parameter ............................................................................... 82
5-15.1 To Change Lead Lag Modulation Backup Sensor............................................................................. 82
5-15.2 To Change Lead Lag Off Hysteresis ................................................................................................. 82
5-15.3 To Change Lead Lag On Hysteresis.................................................................................................. 83
5-15.4 To Change Lead Lag Hysteresis Step Time ...................................................................................... 83
5-15.5 To Change Lead Lag P-I-D Parameters............................................................................................. 83
5-16 Lead Lag Advanced Setting: CH Parameter ............................................................................................ 83
5-16.1 To Change Lead Lag CH Demand Switch ........................................................................................ 83
5-16.2 To Change Lead Lag CH Setpoint Source ........................................................................................ 83
5-16.3 To Change Lead Lag CH Loop Time Of Day Setpoint..................................................................... 83
5-16.4 to change lead lag CH 4-20ma setpoint range................................................................................... 83
5-16.5 To Enable Or Disable Lead Lag CH Loop Outdoor Reset................................................................ 84
5-17 Lead Lag Advanced Setting: DHW Parameter ........................................................................................ 84
5-17.1 To Change Lead Lag DHW Priority Source...................................................................................... 84
5-17.2 To Change Lead Lag DHW Priority Method .................................................................................... 84
5-17.3 To Change Lead Lag DHW Priority Override Time ......................................................................... 84
5-18 Lead Lag Advanced Setting: Frost Protection Parameter ........................................................................ 84
5-18.1 To Enable Or Disable Lead Lag Frost Protection ............................................................................. 84
5-18.2 To Change Lead Lag Frost Protection Setpoint ................................................................................ 84
5-18.3 To Change Lead Lag Frost Protection Rate ...................................................................................... 84
5-19 Lead Lag Advanced Setting: WWSD Parameter ..................................................................................... 85
5-19.1 To Enable Or Disable Lead Lag WWSD .......................................................................................... 85
5-19.2 To Change WWSD Setpoint.............................................................................................................. 85
5-20 Lead Lag Advanced Setting: Algorithms Parameter................................................................................ 85
5-20.1 To Change Lead Selection Method ................................................................................................... 85
5-20.2 To Change Lag Selection Method ..................................................................................................... 85
5-20.3 To Change Lead Rotation Time ........................................................................................................ 85
5-20.4 To Change Forced Lead Rotation Time ............................................................................................ 85
5-21 Lead Lag Advanced Setting: Rate Allocation Parameter......................................................................... 85
5-21.1 To Change Base Load Common Rate ............................................................................................... 85
5-22 Lead Lag Advanced Setting: Add Stage Parameter ................................................................................. 86
5-22.1 To Change Add Stage Method .......................................................................................................... 86
5-22.2 To Change Add Stage Detection Time.............................................................................................. 86
5-22.3 To Change Add Stage Error Threshold ............................................................................................. 86
5-22.4 To Change Add Stage Rate Offset .................................................................................................... 86
5-22.5 To Change Add Stage Interstage Delay............................................................................................. 86
5-23 Lead Lag Advanced Setting: Drop Stage Parameter................................................................................ 86
5-23.1 To Change Drop Stage Method ......................................................................................................... 86
5-23.2 To Change Drop Stage Detection Time ............................................................................................ 86
5-23.3 To Change Drop Stage Error Threshold............................................................................................ 87
5-23.4 to change drop stage rate offset ......................................................................................................... 87
5-23.5 To Change Add Stage Interstage Delay............................................................................................. 87
5-24 Miscellaneous Configuration.................................................................................................................... 87
5-24.1 To Change Alarm Silence Time ........................................................................................................ 87
5-24.2 To Enable Or Disable Pre-Ignition Interlock .................................................................................... 87
5-24.3 To Change Anti Short Cycle Time .................................................................................................... 87

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Rev 2.1
5-24.4 To Change Burner Name................................................................................................................... 87
5-24.5 To Change Installation Data .............................................................................................................. 87
5-24.6 To Change Temperature Units .......................................................................................................... 87
5-24.7 To Turn On And Off The Unit Using Burner Switch........................................................................ 88
5-24.8 To Enable Pump Test ....................................................................................................................... 88
5-24.9 To Enable Modulation Test ............................................................................................................... 88
5-24.10 To Enable Pilot Test ........................................................................................................................ 88
6 Start Up Instructions .......................................................................................................................................... 89
6-1 Factory Test Report (FTR) ......................................................................................................................... 89
6-2 Verification................................................................................................................................................. 90
6-3 Start-Up Detail............................................................................................................................................ 90
6-4 Start Up And Maintenance Tests................................................................................................................ 90
6-4.1 Gas Supply Piping Leak Test .............................................................................................................. 90
6-4.2 Pilot Turndown Test - (Optional at Installation, Required Annually After) ....................................... 91
6-4.3 Pilot Spark Pick Up Test - (Optional at Installation, Required Annually After)................................. 91
6-4.4 Gas Valve Leak Test............................................................................................................................ 92
6-4.5 Safety Shutdown Tests (All Installations) ........................................................................................... 94
6-4.6 Blocked Drain Test - (Optional).......................................................................................................... 95
6-5 Startup Component Adjustments................................................................................................................ 95
6-5.1 Firing Rate Check/Fuel Air Ratio Gas Valve...................................................................................... 95
6-5.2 Air Flow Switch Calibration................................................................................................................ 97
6-6 Combination Fuel Selection ....................................................................................................................... 97
6-7 Shutting Down The Unit ............................................................................................................................ 97
6-8 After Startup Checklist ............................................................................................................................... 98
7 Maintenance....................................................................................................................................................... 99
7-1 Maintenance Descriptions .......................................................................................................................... 99
7-2 Maintenance Schedule.............................................................................................................................. 101
Appendices.......................................................................................................................................................... 102
Appendix A - Troubleshooting And Hold/Lockout Code .............................................................................. 102
Appendix B- Replacement Parts..................................................................................................................... 112
Atlas Warranty.................................................................................................................................................... 114

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Rev 2.1
1 Introduction
This manual covers installation, maintenance, and operation instructions as well as instruction manuals for each of the
control options. Please review this manual carefully before installation or operation. A copy of this manual should be kept
with the boiler at all times for reference. If this manual is misplaced or lost, check the Ace Heating Solutions, LLC.
website, www.aceheatingllc.com , to print from an electronic copy or contact your local Ace Heating Solutions, LLC
representative.
Atlas Series High Efficiency Condensing Boilers have a rugged all-steel frame and low jacket temperatures allowing zero-
clearance installation. It features 6½" forklift holes for easy handing, a front removable exchanger assembly for
serviceability, an efficient blower allowing at least 30 ft each of intake and exhaust vertical venting, and a microprocessor
based flame safeguard with non-volatile ignition lockout.
The heat exchanger tubes are formed into a cylindrical shape to provide maximum waterside and fireside performance.
The entire heat exchanger assembly is easily removable and replaceable using hand tools only, without performing
welding or cutting operations and without the use of gaskets. Your condensing boiler is E.T.L. listed and carries the E.T.L.
listing mark. It is constructed and stamped in accordance with Section IV of the ASME Code, and is stamped on the
nameplate with applicable markings.
Warning: Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal
injury, loss of warranty, exposure to hazardous materials or loss of life. Review the information in this manual carefully.
For your safety: Do not store or use gasoline or other flammable vapors and liquids or other combustible materials in the
vicinity of this or any other appliances. To do so may result in an explosion or fire.
What to do if you smell gas:
xDo not try to light any appliance
xOpen any windows and secure area
xDo not touch any electrical switch; do not use any phone in your building.
xImmediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.
xIf you cannot reach your gas supplier, call the fire department.
Installation and Service must be performed by a qualified installer, service agency or the gas supplier
Warning: Make sure the gas on which the boiler will operate is the same as that specified on the boiler rating plate
(natural gas/propane).
Warning: Caution when servicing gas train components. Propane (LPG) is heavier than air and may trap in pipes, vents,
combustion chamber, or other areas. Always handle with care.
Warning: Should overheating occur or if the gas supply valve fails to shut, do not turn off or disconnect the electrical
supply to the boiler. Instead, shut off the gas supply at a location external to the boiler.
Warning: Do not use this boiler if any part has been under water. Immediately call a qualified service technician to inspect
the boiler and to replace any part of the control system or any gas control which has been under water.
Warning: To minimize the possibility of improper operation, serious injury, fire, or damage to the boiler:
1. Always keep area around the unit(s) free of chlorine, combustible materials, gasoline, and other flammable liquids and
vapors.
2. Water to be heated in the boiler should be free or have low levels of chlorine or other chemicals or water conditions that
would be harmful to the copper heat exchanger. Boiler room ambient temperature shall not exceed 100 degrees F.
3. Boiler should never be covered or have any blockage to the flow of fresh air to the boiler.
Warning: Risk of electrical shock. More than one disconnect switch may be required to de–energize the equipment
before servicing.

9
Rev 2.1
Warning: When servicing ceramic fiber based refractory or insulation blanket, gloves and respirators should be worn to
reduce exposure to airborne Refractory Ceramic Fibers.
Caution: This boiler requires forced water circulation when burner is operating. See minimum and maximum flow rates.
Severe damage will occur if the boiler is operated without proper water flow circulation. A flow switch is used to ensure
that water flows through the boiler, but does not check for the minimum flow rate into the boiler. Numbers are
approximate and may vary depending on installation. See Chart below.
Model
Inlet
Temp
Outlet
Temp
Recommended
Flow rate
Pressure Drop
(ft) for Rec Flow
Min Flow rate
(gpm)
Max Flow rate
(gpm)
500,000 60 79 50 12.5 30 60
750,000 60 88 50 13 30 60
1,000,000 60 97 50 14 30 60
1,500,000 60 116 50 15 30 60
2,000,000 60 97 100 15.5 60 120
2,500,000 60 107 100 17 60 120
3,000,000 60 116 100 18 60 120
xNote for complete information see attached graph for all flow rates for your specific unit.
Table 1.1. Recommended Flow Rates for All Atlas Models
1-1 Pre-Installation
Ace strongly recommends that this manual be reviewed thoroughly before installing your Atlas High Efficiency
Condensing Boiler. Please review the General safety information before installing the boiler. Factory warranty does not
apply to boilers that have been improperly installed or operated (Refer to the warranty in chapter 8). Installation and
service must be performed by a qualified installer, service agency or gas supplier. If, after reviewing this manual, you still
have questions not covered in this manual, please contact the manufacturer or your local Ace representative.
Product Receipt
On receipt of the unit, visually inspect for external damage to the shipping crate or unit. If the crate or unit is damaged,
make a note to that effect on the Bill of Lading when signing for the shipment. Remove the boiler from the shipping
packaging and inspect the unit internally. Report all damages and missing or incorrect parts to the carrier and supplier
immediately. Claims for damages must be filed with the carrier by the consignee. Permission to return goods must be
received from the factory prior to shipping. Goods returned to the factory without an authorized Return Goods
Authorization number will not be accepted. Ace Heating Solutions, LLC. is not responsible for any damage that the unit
receives while in shipping. As each shipping company has its own procedure for filing a claim, please contact the shipper
for claim instructions.
Model Identification
Your Atlas Series Condensing Boiler carries two identification plates: The coil identification plate, which carries the ASME
Code Stamping and Registration Number (when applicable) is attached to the water inlet, with a duplicate on the heat
exchanger top plate. The unit’s nameplate is located on the right side of the rear panel of the unit, and lists information
concerning the input and output of the unit, electrical and gas ratings, working pressure and clearance to adjacent
construction figures. In addition the model and serial numbers are on the plate. You will need these to order replacement
parts from the manufacturing representative in your area or from the factory.
The information on the National Board plate is the same as on the nameplate with the exception of the
National Board registration number, which is required in most states for installation of the unit.
Do not remove any of these plates from the unit for any reason. Removal of these plates will void the warranty.

10
Rev 2.1
1-2 Boiler Nameplate and Model Number
The Boiler Name Plate
The following illustration is an accurate depiction of the nameplate found on the rear side of the boiler. You will also find
an ASME nameplate on the inlet pipe with some of the same information.
A. Boiler description
B. Model number
C. Serial number
D. Minimum relief valve capacity
E. Maximum Btu/Hr fuel input
F. Maximum Btu/Hr output**
G. Boiler horsepower
H. Square feet of heating surface
I. Minimum Btu/Hr fuel input*
J. Minimum Btu/Hr output***
K. Gross E.D.R.
L. Max. allowable working press.***
M. Supply voltage
N. Electrical supply Hertz
O. Electrical supply Phase
P. Required Amperage
Q. Motor amp draw****
R. Control voltage****
S. Control amp draw****
T. Min. Gas pressure*****
U. Max. Gas pressure*****
V. Manifold gas pressure*****
W. Fuel type (See model #)
X. Gallons per hour oil****
Y. Int. Group Prim Safety****
Z. Minimum distances btw. boiler and adjacent construction.
* Minimum Btu/Hr ratings apply to high-low and modulating type boilers only.
** Boiler output ratings are based on factory tests under appropriate conditions. Field results may vary.
*** Maximum allowable working pressure for the boiler. Relief valve set pressure should not exceed the lowest MAWP of any component in your system.
**** Applies to forced draft type burners only
***** Minimum and maximum gas pressure values are measured at the point of connection to the boiler gas train. Manifold gas pressures are measured
after the gas train.
The Boiler Model Number
ATLAS A 150 C - W
Type of boiler:
A = Atlas
Firing Rate:
050 = 500,000 Btu/Hr
075 = 750,000 Btu/Hr
100 = 1,000,000 Btu/Hr
150 = 1,500,000 Btu/Hr
200 = 2,000,000 Btu/Hr
250 = 2,500,000 Btu/Hr
300 = 3,000,000 Btu/Hr
Fuel Type:
G = Natural Gas
P = Propane
C = Combination Natural Gas/Propane (used one at a time)
Jacketing Type:
W = Outdoor

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Rev 2.1
(No Suffix refers to Indoor Jacketing)
1-3 Rating and Certifications
All units must be installed in accordance with all state and local codes, and national codes, including but not limited to:
xANSI Z21.10.2, Gas Water Boilers
xANSI Z223.1/ NFPA 54, National Fuel Code
xANSI/ NFPA 70, National Electric Code
Atlas and Ace Boilers are National Board approved and designed–certified and tested by Intertek (E.T.L.), standards for
the US and Canada (Can Std 1-3.1), and UL 795. Each unit is constructed in accordance with Section IV of the American
Society of Mechanical Engineers (ASME) Boiler Pressure Vessel Code and bears the ASME “HLW” stamp or “H” stamp.
WARNING: Altering any Atlas or Ace boilers pressure vessel by installing replacement heat exchangers, tube
bundles, coils or any ASME parts not manufactured and/or approved by Ace will instantly void the ASME and
E.T.L. rating of the vessel and any Ace warranty on the vessel. Altering the ASME or E.T.L. ratings of the vessel
also violates national, state, and local approval codes.
Installations at Elevation
Rated inputs are suitable for up to 2,000 ft. elevation without de-rating. Consult the factory for installations over 2,000 ft.
above sea level. No hardware changes are required to the unit. (Adjustments may be required).
1-4 Connection Information
Figure 1.1. Atlas Connection Diagram
1-5 General Safety
In order to meet commercial hot water needs, the high limit safety control on this hot water boiler is adjustable up to 240
degrees F by the OEM or installer only. However, water temperatures exceeding over 125 degrees can cause instant
MODEL AIR
INTAKE
EXHAUST
VENT
WATER
IN/OUT
PROPANE/NATURAL
GAS INLET
A050 4" 6" 2" 1"
A075 4" 6" 2" 1"
A100 6" 8" 2" 1"
A150 6" 8" 2" 1 ¼"
A200 8" 10" 2 ½" 1 ¼"
A250 10" 12" 2 ½" 1 ¼"
A300 10" 12" 2 ½" 1 ¼"
CONNECTION SIZES

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Rev 2.1
and severe burns or death from scalds. When supplying general purpose domestic hot water, the recommended
setting for the Operating control is 125 degrees F.
Safety and energy conservation are factors to consider when setting the temperature aquastat on the unit. The most
energy–efficient operation will result when the temperature setting is the lowest that satisfies the needs of the application.
Maximum outlet water temperatures are seen when the boiler reaches the high temperature limit and shuts off. To test the
maximum water temperature delivered, turn on the hot water on a faucet and use a thermometer to read the outlet
temperature.

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Rev 2.1
2 Installation
2-1 Installation Codes
Installations must follow these codes:
xLocal, state, provincial, and national codes, laws, regulations and ordinances
xNational Fuel Gas Code, ANSI Z223.1/ NFPA 54 – latest edition (NFGC)
xNational Electrical Code, ANSI/ NFPA 70 – latest edition (NEC)
xStandards for Controls and Safety Devices for Automatically Fired Boilers, ANSI/ASME CSD–1, (CSD–1) when
required.
Note: If any code listed above conflict, the stricter of the conflicting codes shall be followed
for installation.
Note: Installation and Service must be performed by a qualified installer, service agency or the
gas supplier
2-2 Equipment Base
The boiler should be mounted on a level, structurally sound surface. The boiler is approved for mounting on a combustible
surface but cannot be installed on carpeting. Gas fueled equipment installed in enclosed parking garages must be located
at least 18" above the floor.
Note: Ace strongly recommends that you secure the boiler to the base pad by the mounting holes provided at the base of
the unit.
Figure 2.1. Isometric View of Atlas Base with Mounting Holes
Caution: Locate the unit so that the condensate can be treated and piped to meet city and local code requirements.
The boiler shall be installed such that the gas ignition system components are protected from water (dripping, spraying,
rain, etc.) during boiler operation or service (circulator replacement, control replacement, etc.)
2-3 Determining Unit Location
The optimal location for the boiler is as close to an exterior wall as possible to reduce vent loss and to minimize the costly
exhaust Stainless Steel vent materials. Maintain minimum specified clearances for adequate operation. All installations

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Rev 2.1
must allow sufficient space behind the boiler to service vent connections, water pipe connections, piping and other
auxiliary equipment, as well as the appliance.
MODEL TOP
CLEARANCE
FRONT
CLEARANCE
SIDE
CLEARANCE
BOTTOM
CLEARANCE
A050 18" 36" 6" 0"
A075 18" 36" 6" 0"
A100 18" 36" 6" 0"
A150 18" 36" 6" 0"
A200 22" 40" 6" 0"
A250 22" 40" 6" 0"
A300 22" 40" 6" 0"
Table 2.1. Atlas Minimum Clearances
Multiple appliances may be installed side by side with 6" clearance between adjacent appliances to allow sufficient air for
the pilot blower. It is recommended to maintain 16" clearance between adjacent boilers to allow access for service to the
rear of the unit.
The minimum clearance between an Atlas boiler and a storage tank is 6". For alcove installations, the minimum clearance
to combustible construction is 6" to side, 24" to rear walls and 22" from top of the unit to the ceiling. The front alcove shall
remain open. This will allow boiler to be serviced in its location without movement or removal of the unit.
Note: Local and state codes requiring greater clearances supersedes these minimum clearances.
Outdoor Installations (Optional)
Atlas Condensing Boilers can be design–certified for outdoor installation. Boilers must not be installed under an overhang
that is less than 3’ from the top of the vent terminal. Three sides must be open in the area under the overhang. Roof water
drainage must be diverted away from the boiler(s) installed under overhangs.
It is highly recommended that you allow sufficient space in front and the rear of the unit for replacement and adjustment of
all parts requiring such attention.
Caution: Keep the area around the unit(s) free from combustibles and flammable liquids.
2-4 Combustion and Ventilation Air
WARNING: THE LACK OF ADEQUATE COMBUSTION AIR IS THE SINGLE BIGGEST OPERATING PROBLEM
ENCOUNTERED WITH GAS FIRED WATER BOILERS
Note: Use of the boiler in construction areas where fine particulate matter, such as concrete dust or dry wall dust, is
present may result in damage to the boiler that is not covered by the warranty. If operated in a construction environment,
a clean source of combustion air must be provided directly to the boiler.
Your Atlas boiler is equipped with a filter to help prevent such an occurrence above and must be checked at least every
month. A single replacement filter is located inside the control box.
Indoor Units (Standard)
The boiler must be supplied with sufficient quantities of non–contaminated air to support proper combustion and
equipment ventilation. Combustion air can be supplied via conventional means where combustion air is drawn from the
area immediately surrounding the boiler, or via direct vent, where combustion air is drawn directly from outside. All
installations must comply with the requirements of the National Fuel Gas Code, NFPA 54, Canada B149, and all local
codes.
Note: In calculating free area, the required size of the opening for combustion, ventilation, and dilution air shall be based
on net free area of each opening. If free area through a design of louver or grill is known, it shall be used in calculating the
size opening required to provide the free area specified. For additional information, refer to the latest NFGC code
requirements.

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Rev 2.1
Provisions for combustion and ventilation air must be in accordance with Air for Combustion and Ventilation, of the latest
edition of the National Fuel Gas Code, ANSI Z223.1, in Canada the latest edition of CGA Standard B149 Installation Code
for Gas Burning Appliances and Equipment, or applicable provisions of the local building codes. In order to protect
electrical components, the boiler room ambient air temperature shall not exceed 100 F.
The equipment room MUST be provided with properly sized openings to assure adequate combustion and ventilation air
when unit is installed with a basic Category IV venting system.
Note: All additional gas fired equipment should be considered when calculating the necessary air supply.
Direct vent
If outside air is drawn through the intake vent directly to this unit for combustion:
1. Install combustion air direct vent in accordance with drawing below. (Refer to Section 2-6 for details)
Figure 2.2. Atlas with Vertical Intake and Exhaust Venting
Figure 2.3. Atlas with Horizontal Intake and Exhaust Venting

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Rev 2.1
2. The exhaust vent must be installed with a slight upward slope of not more than ¼ inch per foot of horizontal run to
vent terminal.
3. The exhaust vent must be insulated through the length of the horizontal run.
4. Intake and Exhaust vents with vertical termination should have a rain cap installed.
5. It is recommended to install a drain on the exhaust vent.
6. In cold climates, and to mitigate potential freeze up, Ace highly recommends the installation of a motorized sealed
damper to prevent circulation of cold air through the boiler during the non – operating hours. When installing
motorized damper actuator with switch contacts, prove the damper is fully open to prevent unit from firing when
damper is not fully open.
2-5 Conventional Combustion Air Supply
U.S installations
All Air from inside the building: If all combustion air is drawn from inside the building, the mechanical equipment room
does not receive air from outside, the following applies:
1. The mechanical room must be provided with two permanent openings communicating directly with additional
room(s) of sufficient volume so that the combined volume of all spaces meets the criteria for an unconfined space.
(An unconfined space is defined as a space whose volume is more than 50 cubic feet per 1,000 BTUH of the
aggregate input rating of all appliances installed in that space. (NFGC).
2. Each opening must have a minimum free area of 1 sq. in. per 1,000 BTUH of the total input rating of all gas
utilization equipment in the mechanical room.
3. One opening must commence within 12" of the top, and one opening must commence within 12" of the bottom of
the room.
Ace recommends that one opening shall commence with 6" from the top and one opening shall commence 6" from the
bottom. The combined area of the two opening should not be less than 200 sq. in. for the first 100,000 BTUH boiler input,
and 100 sq. in. for each additional 100,000 BTUH boiler input.
All Air from Outdoors: If all the combustion air is drawn from the air outside the building, the mechanical equipment
room directly communicates with outdoor air, either of the following methods can be used:
Method 1:
1. The mechanical equipment room must be provided with two permanent opening, one commencing within 12" of
the top and one commencing within 12" from the bottom of the room.
2. The opening must communicate directly, or by ducts, with the outdoors
3. Each opening must have a minimum free area of 1 sq. in. per 4,000 BTUH of all equipment in the room when the
opening is communicating directly with the outdoors or through vertical ducts. The minimum free area required for
horizontal ducts is 1 sq. in. per 2,000 BTUH of the total input rating to all the equipment in the room.
(For addition information, refer to the latest NFGC)
Method 2 (normally applied in cold climate regions):
1. The mechanical equipment room must be provided with at least one permanent opening, commencing within 12"
of the top of the enclosure.
2. The opening must communicate directly or by ducts with the outdoors.

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Rev 2.1
3. The opening must have a minimum free area of 1 sq. in. per 3,000 BTUH of the total input rating of all equipment
in the room, or no less than the sum of the areas of all vent connectors in the confined space.
(For additional information, referred to the latest NFGC)
Warning: Do not use the “one permanent opening” method if the equipment room is under negative pressure conditions
or the equipment is common vented with other gas fired appliances.
Note: Louvers and grilles. The required size of opening for combustion, ventilation and dilution air shall be based on the
net free area of each opening. Where free area through a design of louver or grille is known, it shall be used in calculating
the size opening required to provide the free area specified. Where the louver and grille design and free area are not
known, it shall be assumed that wood louvers will have 25% free area, and metal louvers and grilles will have 75% free
area (NFGC).
Canadian Installation
Caution: All combustion air must be drawn from the outside air of the building; the mechanical equipment room must
communicate directly with outdoor air.
1. Ventilation of the space occupied by the boiler shall be provided by an opening(s) for ventilation air at the highest
practical point communicating with the outdoors. The total cross-sectional area of such an opening(s) shall be at
least 10% of the area required in (2) below, but no less than 10 sq. in.
2. For boilers using a barometric damper vent system there shall be a permanent air supply opening(s) having a
cross section area of not less than 1 sq. in. per 7,000 BTUH up to and including 1 million BTUH, plus 1 sq. in. per
14,000 BTUH in excess of 1 million BTUH. This opening(s) shall be located at or ducted to a point no more than
18" nor less than 6" above floor level. The duct can also “goose neck” through the roof. The duct is preferred to be
straight down and terminated 18" from the floor, but not near the piping. This air supply opening requirement shall
be in addition to the air opening for ventilation air required in (1). (above)
3. For additional information, referred to CGA, B149
Warning: Care must be taken to ensure that the equipment room is not under negative pressure conditions.
2-6 Conventional Exhaust Venting
Caution: Proper installation of flue venting is critical for the safe and efficient operation of the boiler.
Definition of ANSI Categories for High Efficiency Appliances
Boilers are divided into four categories based on the pressure produced in the exhaust and the likelihood of condensate
production in the vent.
Category I A boiler which operates with a non-positive vent static pressure and with a vent gas temperature that avoids
excessive condensate production in the vent.
Category II: A boiler which operates with a non-positive vent static pressure and with a vent gas temperature that may
cause excessive condensate production in vent.
Category III: A boiler which operates with a positive vent pressure and a vent gas temperature that avoids excessive
condensate production in the vent.
Category IV: A boiler which operates with a positive vent pressure and with a gas temperature that may cause
excessive condensate production in the vent.
Note: These definitions apply to the appliances and do not necessarily reflect the performance of the connected vent
system.
Note: For additional information on appliance categorization, see appropriate ANSI Z21 Standard and the NFGC (US), or
CGA (Canada) B149, or applicable provisions of local building codes.

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Rev 2.1
Note: Your Atlas Series Condensing Boiler requires Category IV venting. (See NFGC, NFPA 54, Section 7 “Venting
Equipment” for more detailed information).
The Atlas is designed to operate with a chamber pressure of 0 to +0.5" w.c. The Atlas Condensing boiler is capable of
100 feet of vertical equivalent exhaust when equipped with the standard exhaust vent. When more than 100 feet of
exhaust venting is used, the chamber pressure could increase beyond the maximum designed +0.5”w.c. An optional
enlarged vent maybe be used to increase vent runs in case more than the 100ft maximum is needed, however venting
must be designed by a professional to ensure the boiler chamber pressure stays within the designed range. Boiler vents
must be constructed of AL29-4C or similar suitable material acceptable for use with exposure to condensate.
Atlas combustion air intake can be taken using the boiler room air or may be vented directly outside. When using direct
combustion air venting, the Atlas is capable of up to 30ft of equivalent venting. If more than 30ft of equivalent venting
must be used, an enlarged vent diameter may be used to extend maximum vent lengths, but must be properly sized to
allow for sufficient combustion air to be supplied to the boiler. Although direct intake is possible, it is recommended to take
combustion air from a well ventilated boiler room.
Warning: Using improper venting materials can result in personal injury, death or property damage.
Support of the vent stack
The weight of the vent stack or chimney must not rest on the boiler vent connection. Support must be provided in
compliance with applicable codes. The vent should also be installed to maintain proper clearances from combustible
materials. Use insulated vent pipe spacers where the vent passes through combustible roofs and walls.
Vent Termination Location
Note: During winter months check the vent cap and make sure no blockage occurs from buildup of snow and ice.
Condensate can freeze on the cap. Frozen condensate on the vent cap can result in a blocked flue.
1. Give special attention to the location of the vent termination to avoid possibility of property damage or personal
injury.
2. Gases may form a white vapor plume in the winter. The plume could allow hazardous flue gas in through an open
window or obstruct a window view if the termination is installed near windows.
3. Prevailing winds, in combination with below freezing temperatures, can cause freezing of condensate and
water/ice build up on building, plants or roofs.
4. The bottom of the vent terminal and air intake shall be located at least 12" above grade, including normal snow
line.
5. Un-insulated single wall Category IV metal vent pipe shall not be used outdoors in cold climates for venting gas –
fired equipment without insulation.
6. Through the wall vents for Category IV appliances shall not terminate over public walkways or over an area where
condensate or vapor could be detrimental to the operation of regulators, relief valves, or other equipment.
7. Locate and guard vent termination to prevent accidental contact by people or pets.
8. Do not terminate vent in window well, stairwell, alcove, courtyard or other recessed area.
9. Do not terminate above any door, window, or gravity air intake. Condensate can freeze, causing ice formations.
10. Locate or guard vent to prevent condensate from damaging exterior finishes. Use a rust resistant sheet metal
backing plate against brick masonry surfaces.
11. Do not extend exposed vent pipe outside of building beyond minimum distance required for vent termination.
Condensate could freeze and block vent pipe.

19
Rev 2.1
US Installations
Refer to the latest edition of the National Fuel Gas Code.
1. Vent must terminate at least 4ft below, 4 ft horizontally from or 1 ft above any door, window or gravity air inlet to
the building.
2. The vent must not be less than 7ft above grade when located adjacent to public walkways.
3. Terminate vent at least 3ft above forced air inlet located within 10ft.
4. Vent must terminate at least 4ft horizontally, and in no case above or below unless 4ft horizontal distance is
maintained, from electric meters, gas meters, regulators, and relief equipment.
5. Terminate vent at least 6ft away from adjacent walls.
6. Do not terminate vent closer to 5ft below roof overhang.
7. Terminate vent at least 1ft above grade, including snow line.
8. Multiple direct vents installations require a 4ft clearance between the ends of vent caps located on the same
horizontal plane.
Canadian Installations
Refer to the latest edition of CGA, B149 Installation Code.
1. A vent shall not terminate directly above a paved sidewalk or driveway which is located between two single –
family dwelling and serves both dwellings.
2. A vent shall not terminate less than 7ft above a paved sidewalk or paved driveway located on public property.
3. A vent shall not terminate within 6ft of a mechanical air supply inlet to any building.
4. A vent shall not terminate above a meter/regulator assembly within 3ft horizontally of the vertical centre – line of
the regulator.
5. A vent shall not terminate within 6ft of any gas service regulator.
6. A vent shall not terminate less than 1ft above grade level.
7. A vent shall not terminate within 3ft of a window or door which can be opened in any building, any non –
mechanical air supply inlet of any other appliance.
8. A vent shall not terminate underneath a verandah, porch or deck, unless the verandah, porch or deck is fully open
on a minimum of two sides beneath the floor, and the distance between the top of the vent termination and the
underside of the verandah, porch or deck is greater than 1ft.
Venting Tips:
Support piping: For horizontal runs, add supports at least every 5ft.; For vertical runs, use braces under or near elbows.
Warning: Examine the venting system at least once a year. Check all joints and vent pipe connections for
tightness, corrosion or deterioration.
Venting Configurations
For boilers connected to gas vents or chimneys, vent installations shall be in accordance with the NFGC (US) or CGA,
B149 (Canada), or applicable provisions of local building codes.

20
Rev 2.1
Vertical Venting (Category IV)
The maximum and minimum venting length for this Category IV appliance shall be determined per the NFGC (US) or
CGA, B149 (Canada).
The diameter of the vent flue pipe should be sized according to NFGC (US) and Appendix B of the CGA, B149 (Canada).
The minimum flue diameter for conventional venting using Category IV, stainless steel AL29-4C vent is:
6 inches for Models A050 – A075
8 inches for models A100 – A150
10 inches for model A200
12 inches for models A250 – A300
The connections from the appliance vent to stack must be as direct as possible and shall be same diameter as the vent
outlet. The horizontal breaching of a vent must have an upward slope of not less than ¼" per linear foot from the boiler to
vent terminal. The horizontal portions of the vent shall also be supported for the design and weight of the material
clearances and to prevent physical damage or separation of joints.
Note: A vent adapter (field supplied) may be required to connect the Category IV vent to the boiler.
Termination
The vent terminal should be vertical and should terminate outside the building at least 2ft above the highest point of the
roof that is within 10ft. The vent cap should have minimum clearance of 4ft horizontally from, and in no case above or
below (unless a 4ft horizontal distance is maintained), electric meters, gas meters, regulators and relief equipment. The
distance of the vent terminal from adjacent public walkways, adjacent building, open windows and building opening must
be consistent with the NFGC (US) or CGA, B149 (Canada). Gas vents supported only by flashing and extended above the
roof more than 5ft should be secured by guy-wires or braced to withstand snow and wind loads.
Caution: A listed vent cap terminal suitable for connection to the Category IV vent materials, adequately sized, must be
used to evacuate the flue products from boilers.
Common Venting
The NFGC does not address sizing guidelines for the common venting of multiple Category IV boilers. When common
venting multiple units together, the venting must be designed by a professional engineer to ensure the chamber pressure
of each boiler is always below 0.5” w.c. at high fire.
Warning: Vent connectors serving any other appliances shall not be connected into any portion of the mechanical draft
systems operating under positive pressure. If an Ace unit is installed to replace an existing boiler, the vent system must be
verified to be of the correct size and of Category IV AL29-4C vent material. If it is not, it must be replaced.
2-7 Gas Supply
Danger: Make sure the gas on which the boiler will operate is the same as that specified on the boiler rating plate (natural
gas/propane).
The gas line should be a separate line running directly from the gas meter to the unit, unless the existing gas line is of
ample capacity. Verify the capacity of the existing gas piping if it is to be used.
The gas pipe must have a sediment trap ahead of the boiler connection controls and a manual shut – off valve (one set for
each fuel source if using an Atlas Combination Fuel Unit) located outside the boiler cabinet. It is highly recommended that
a union be installed in the gas supply line adjacent to the boiler for serving (see diagram below). The maximum working
gas pressure for both natural gas and propane is 14" w.c. Keep in mind that an increase the gas pressure, without
making additional adjustments, leads to an increased BTU input and a decreased efficiency.
Caution: If the gas pressures exceed 14" w.c., a gas pressure regulator must be installed prior to the gas connection to
reduce the supply pressure.
WARNING: A sediment trap MUST be installed on the gas piping for each gas line.