Applications ManualGas condensing boilerWARNING!Improper installation, adjustment, alteration, service or maintenancecan cause injury, loss of life or property damage. Refer to theinstallation and operating manuals. For assistance or additionalinformation, consult a trained and certified installer, service agencyor the gas supplier.CAUTION!The installation and operating manuals are part of the documentationthat is delivered to the installation's operator. Go through theinformation in this manual with the owner/operator and make sure thathe or she is familiar with the appliance and its operation.Logamax plus GB142

2 Technical specifications are subject to change without prior noticeGB142 Applications ManualLogamax plus GB142 applications manual 04.2017

3GB142 Applications ManualTable of Contents1 Reference Documents42 Boiler Components & Controls52.1 Periphery62.2 Low Loss Header (LLH)72.3 AM10 Outdoor Reset Modulating Boiler Control92.4 RC35 Room Controller and User Interface132.5 0-10V BMS Interface & Common Fault Module EM10202.6 MCM10 Multi Cascade Module213 Sample Applications25Legend263.1 System 1: Single boiler with outdoor reset, multipleheating zones with zone pumps and DHW273.2 System 2: Single boiler with outdoor reset, multipleheating zones with zone relays and DHW313.3 System 3: Single boiler with RC35, one heating zone,WM10 and DHW priority353.4 System 4: Single boiler with RC35, WM10, SM10,one heating zone, & solar thermal DHW393.5 System 5: Multi-boiler Cascade43Appendix47Appendix 1 - Single boiler with 0-10V heat demand input48Appendix 2 - Multi-boiler cascade with 0-10V heatdemand input50Appendix 3 - Adding DHW priority to a multi-boilercascade52Logamax plus GB142 applications manual 04.2017Technical specifications are subject to change without prior notice

4 GB142 Applications Manual1 Reference DocumentsThe following table references all related documentation to theGB142 series boiler. To obtain copies of these documents,please go to our website at NameDescription Of ContentsInstallation Instructions Safety and general instructionsProduct specificationsInstallationElectrical connectionsOperation (start-up and shut down procedure)Servicing Instructions Product descriptionSafety and general instructionsOperationSymptomsDiagnosisInspection / MaintenanceUser‘s Instructions Safety informationLighting instructionsOperating the BC10 basic controllerBoiler start-up and shut downOperating and error messagesRecord Book - Water Quality Requirements Requirements Operator‘s logPropane Conversion Kit Instructions Technical Service Bulletin:TBG-03 Removing Fan Assembly Service manual supplement Replacement instructionsTechnical Service Bulletin:TBG-04 Flue Gas Venting Requirements for Canada ULC S636 venting standard for CanadaTechnical Service Bulletin:TBG-05 Guidelines for Venting Through Unconditioned Space Installation requirements for venting throughunconditioned spaceTechnical Service Bulletin:TBG-06 Burner Removal & Installation Service manual supplement Replacement instructionsTechnical Service Bulletin:TBG-07 Boiler Water Chemistry & Freeze Prevention Guidelines Technical Service Bulletin:TBG-08 Pressure Sensor Maintenance Problem statement and cause Corrective action and work instructionTechnical Service Bulletin:TBG-10 Side Wall Vent Termination Spacing for Multiple Boilers Clearance guidelines - Stainless Steel concentric vents Clearance guidelines - PVC concentric ventsTechnical Service Bulletin:TBG-22 Condensate Tee Installation Location requirements Installation requirementsTechnical Service Bulletin:TBG-24 Vent Adaptor Change Notification of adaptor release Benefits of adaptorTechnical Service Bulletin:TBG-27 High Limiit Validation Procedure High limit test procedureSafety considerationsParts listLiquid Propane conversionOperating instructionsRecommended steps for commissioning boilerWater chemistry guidelinesDielectric isolationCleaning requirements / Eliminating system leaksAluminum safe anti-freeze guidelinesBuderus selected suppliers of water treatment productsTable 1Technical specifications are subject to change without prior noticeLogamax plus GB142 applications manual 04.2017

GB142 Applications Manual 52 Boiler Components & ControlsThis chapter outlines the various components availablewith the GB142 series boiler along with the following controloptions: AM10 - Outdoor Reset Modulating Boiler Control MCM10 - Multi-boiler Cascade Module RC35 - Energy Management System (EMS) withOutdoor Reset, Room Reset, Zoning and SolarThermal capabilities Logamatic 4000 Control System (see Logamatic 4000Applications Manual)This manual outlines the most common applications availableusing these components and controls. These applicationsections contain diagrams of preferred piping with associatedwiring diagrams and controller programming, along withadditional important information.Logamax plus GB142 applications manual 04.2017Technical specifications are subject to change without prior notice

6 GB142 Applications Manual2.1 Periphery2.1.1 Low Water Cut-off (LWCO) and External Manual Reset High LimitNational or local code may require the installation of an externalLow Water Cut-Off (LWCO) and/or an External Manual ResetHigh Limit.Notes:1. Contractor to furnish and install LWCO and Manual ResetHigh Limit devices as required by local codes.2.Do not install any type of valve or check valve in betweenboiler and LWCO or Manual Reset High Limit.3.Refer to the manufacturer’s instructions when installingLWCO and Manual Reset High Limit.4.LWCO is installed external to the boiler and mustbe located above the highest point of the boiler heatexchanger.5.Manual Reset High Limit remote sensing bulb must belocated in the boiler supply.6.In a cascade each boiler must be equipped with its ownLWCO and Manual Reset High Limit.Installation instructions (Fig. 1):At the back of the boiler manifold remove the 1” plug andconnect a 1” Tee. At the horizontal end connect a 1” well forthe Manual Reset High Limit probe. At the vertical connectorof the Tee, install a 1” stand pipe that reaches above thehighest point of the boiler heat exchanger. Install a secondTee with an automatic air vent at the top and a LWCO justbelow.Wire the LWCO and the Manual Reset High Limit normallyclosed dry contacts in series with EV pins 1 and 2 on theboiler, which will shut off the burner when the connection isinterrupted.Fig. 1 Low Water Cutoff viewsNOTE: Power supply to LWCO and external high limit not shown for clarity. Follow manufacturer’s instructions.Technical specifications are subject to change without prior noticeLogamax plus GB142 applications manual 04.2017

7GB142 Applications ManualIn the system under flowing can result in too great a delta T,resulting in considerable heat being shed in the beginning ofthe loop and insufficient heat left for the remainder of the loop.2.2 Low Loss Header (LLH)2.2.1 General InformationInstallation of a LLH however requires a pump on the boilerside and one on the system side.As their flow rates are typically low, some manufacturers designa LLH to include an air eliminator and dirt separator.GB142GB142A typical example is a system with low mass boilers andmultiple zones with zone pumps. The LLH ensures a constantflow rate through the boilers independently of how manyzones are calling and independently of the flow rate in thesystem loop. It prevents pumps from working against eachother, resulting in balanced flows, even heat distribution, andreduction of potential noise.Fig. 2 Two Boiler System with Low Loss HeaderSupplySupplyBOILERSYSTEMReturnReturnFig. 3 Low Loss Header OverviewModern compact wall hung gas appliances are often equippedwith boiler controlled modulating pumps, some of which arealso used for making DHW. These pumps are operating in waysthat optimize boiler efficiency and longevity, but are not suitablefor supplying the system at the same time. As a result thesystem must be set up with hydraulic separation between theprimary and secondary sides.A LLH is nothing more than a large pipe, installed betweenthe heat sources and the system. It is used in single and multiboiler installations of appliances with small water volumes toindependently control the flow of water in the boiler loop andthe system loop.When the circulating volumes between boiler loop and systemloop differs greatly, a LLH can help avoid over flowing or underflowing one or the other. Over flowing can lead to noise anderosion in the piping, and can be identified by a boiler or systemnot coming up to temperature, or by a narrow delta T. Underflowing means that the heat is not being transported away fromthe boiler, causing it to bounce off the high limit.Logamax plus GB142 applications manual 04.2017Technical specifications are subject to change without prior notice

8 GB142 Applications ManualPossible scenarios of the LLH:V₁V₂R₁R₂Both primary and secondary flow ratesare identical.V₁R₁V₂R₂The boiler flow rate is greater than thesystem flow rate and hot supply wateris returning to the boiler.V₁V₂R₁R₂The system flow rate is greater than theboiler flow rate and cold return water is sentback out to the system.Fig. 4 Three possible flow patterns with a LLHA LLH is typically equipped with a well for a system strategysensor to measure supply water temperature. If this is not thecase the system supply temperature sensor should be strappedonto the system supply pipe coming off the LLH.A LLH is oversized to a point that it can handle the maximumpossible flow rates on either side without significant pressuredrop.In the center of the LLH is the point of equilibrium and zeropressure. It allows for a variety of flow rates to occur on bothsides of the system without influencing the other side.A common case from retrofit applications: The system pumpsare too strong and remove more water from the LLH thandelivered by the boiler. With the consequence that none ofthe zones gets up to temperature. Required measure: reducesystem flow rates.For system redundancy, energy optimization, or combinationof different fuel types, different boiler types or models may becombined in systems. Based on the load this allows turningoff complete appliances resulting in higher efficiencies of theremaining system.When a larger heat demand occurs additional boilers can beenabled one by one. The changing flow rates are balanced bythe LLH and all boilers and zones in operation are continued tobe supplied with the necessary volumes.Example:Old boiler output 480 MBH (140 kW)New boiler output: 340 MBH (100 kW)The new system requires a system flow rate of 19 gpm (4300liters/hr) at 36 F (20 C) delta T.As older systems are typically equipped with oversized pumps,the retrofit system can be expected to use pumps that maybe half the size of the old ones. In this case only a LLH allowsbalancing of the primary and secondary flow rates.It is recommended to use multi speed or ECM pumps.Sizing a Low Loss HeaderSize the pumps and LLH by the greater of the two volumes thatis circulating: boiler circuit or system circuit.Note: It is recommended to set the minimum delta T betweenboiler supply and boiler return to 20 to 25 F (10 to 15 C) byadjusting the speed of the circulator or installing flow setters.For sizing a LLH at maximum throughput the flow rate shouldnot exceed 0.67 feet/second (0,2 m/s). This makes the LLHthe area of slowest velocity and allows it to be used as an airseparator and dirt separator.Over sizing a LLH however does not have negativeconsequences on the system. In fact a buffer tank can be usedinstead of a LLH.To ensure efficiency while also providing redundancy, eachboiler must have its own boiler pump.In particular when an existing system is retrofit with a new boilerit is necessary to evaluate the boiler and system flow rates. Areduction of boiler output can in many cases reach 40% andcompletely change system hydraulics.Technical specifications are subject to change without prior noticeLogamax plus GB142 applications manual 04.2017

9GB142 Applications Manual2.3 AM10 Outdoor Reset Modulating Boiler ControlProduct DescriptionThe AM10 is a modulating outdoor reset control for Buderusboilers equipped with the EMS bus. It sets the supply watertemperature based on outdoor temperature. The boiler fires,runs and modulates based on the information received from theAM10, taking into consideration the delta T between supply andreturn.An ON/OFF signal from a third party room thermostat orzone controller (not included) is used to communicate a heatdemand. The AM10 offers warm weather shutdown (WWSD)when the outdoor temperature rises above a custom setabletemperature (default: 70 F (21 C)).To control and stage multiple boilers, combine the AM10 with anMCM10 cascade module.Outdoor resetOutdoor reset is a way to economically control space heatingbased on the outdoor temperature. It functions based on thefact that the colder the weather the greater the heat loss of astructure, and the higher the supply water temperature neededto heat the house. On a warmer day with smaller heat loss alower water temperature will be able to heat the house. This hasseveral advantages:Fig. 5 AM10 Modulating Control1. Save fuel by running the boiler at lower temperatureswhich reduces the heat going up the chimney.2. Lower water temperatures allow taking advantage of theenergy trapped in the flue gases (latent heat) in acondensing appliance.3. Added comfort because temperature changes are not feltwith lower water temperatures running constantly.To achieve these goals the reset curve must be properlyadjusted to match the application and the heat loss ofthe structure. The reset curve tells the boiler what watertemperature is needed at a certain outdoor temperature.Outdoor reset is the preferred control when using multiplezones, as the boiler supply water temperature is not dictated bya master or largest zone, but solely based on the heat loss ofthe structure.Logamax plus GB142 applications manual 04.2017Technical specifications are subject to change without prior notice

10 GB142 Applications ManualHeating curveThe AM10 has a built in linear heating curve that sets the supplywater temperature in relation to the outdoor temperature.Top of heating curve represents the water temperature at 14 F(-10 C) outdoor temperature. Based on type of heating systemdifferent water temperatures are recommended for bottom ofheating curve. The boiler follows the heating curve in the AM10up to the maximum supply water temperature set on the boilerdial which works as a high limit (in cascades always set toAUT). In addition the warm weather shut down (WWSD) turnsthe heating system off when the temperature outdoors risesabove a certain value.Heating curve chart in Degrees Fahrenheit:200194190Boiler High LimitRadiant FloorPanelRadiatorsBaseboardHydro AirCast Iron Radiators180170Supply Water Temperature [ F]160150140130120Use high limit to preventradiant floor damagefrom overheating.(not in cascades)1101009080Upper Reference pointHeating curve base point70WWSD factory default60807060504030Outdoor Temperature [ F]2014100-10Fig. 6 Heating curve chart in Degrees FahrenheitOutdoorTemperature( F)Radiant FloorPanelRadiatorsCast IronRadiatorsBaseboardHydro 507085989898148Technical specifications are subject to change without prior noticeLogamax plus GB142 applications manual 04.2017

11GB142 Applications ManualHeating curve chart in Degrees Celsius:100Boiler High Limit9090Radiant FloorPanelRadiatorsBaseboardHydro AirCast Iron Radiators80Supply Water Temperature [ C]706050Use high limit to preventradiant floor damagefrom overheating.(not in cascades)403020Heating curve base point10Upper Reference pointWWSD factory default02520101505Outdoor Temperature [ C]-5-10-15-20Fig.7 Heating curve chart in Degrees Celsius( C)OutdoorTemperatureRadiant FloorPanelRadiatorsCast IronRadiatorsBaseboardHydro 764Logamax plus GB142 applications manual 04.2017Technical specifications are subject to change without prior notice

12 GB142 Applications ManualWWSDSingle Boiler ControlWarm weather shut down (WWSD) temperature is factory setfor 70 F (21 C). If the outdoor temperature rises above thissetting, the boiler will be turned off except for generating DHW.The value can be adjusted between 32 F (0 C) and 86 F(30 C).To equip a single GB142 boiler with outdoor reset control, thefollowing items are recommended: (not included) ON/OFF thermostat for each heating zone Pump relay or zone valve panel according to the numberof zones Low and high voltage wiring, 24VAC transformer, etc.Mounting of the AM10Wiring Details:If there are multiple zones, wire all closed contacts to the AM10so that each call for heat produces a heat demand.The recommended mounting locations are either on the wallnext to the boiler or on the boiler jacket. A mounting bracket isincluded with the controller.Positioning the outdoor sensorFor best performance the outdoor sensor is to be positionedat a location where it is not influenced by sunlight. Mount onlyon a North facing wall of the building, and at least 1 foot abovesnow line. Keep the sensor away from heat sources such as adryer, water heater, or boiler vents, windows, etc.Set the BC10 central heating dial to automatic (AUT), unlessthe system consists exclusively of low temperature radiant,where the central heating dial can be used as a high limitprotection. In cascades the AUT setting is required.Note: Do not install an RC10, EM10, or RC35 when using thisconfiguration as these devices do not coexist with theAM10. For multi-boiler systems add the MCM10 cascademodule between the AM10 and the boilers.toMulti-Zone Relay BoxFig. 8 Installation example with zone relay boxTechnical specifications are subject to change without prior noticeLogamax plus GB142 applications manual 04.2017

13GB142 Applications Manual2.4 RC35 Room Controller and User InterfaceThe RC35 is an outdoor reset based heating system controlwith room influence and optional solar thermal DHW generationcapability.2.4.2 Overview2.4.1 Features and benefits Outdoor reset Room reset or room influence Setback options- Room setback- Night setback- Outdoor setback- Shut-down 8 pre-loaded time programs with option to create customprogram System Efficiency- Microprocessor coordinates boiler operation to ensuremaximum comfort with optimized energy usage- Adjustable warm weather shut down (WWSD)- Room influence setting to prevent zone overheating Monitoring- Monitoring of system data including operating hours andburner starts- Solar thermal gain monitoring in combination with SM10module User friendly- Easy to use due to LCD display with full text- Relay testing for start-up, commissioning andtroubleshooting to verify proper wiring Service information- Service and diagnostic system simplifies troubleshooting- Maintenance reminder feature alerts the operator whenservicing is due Modular structure of the control system allows customizingfor many applications- Up to 4 heating zones (3 mixed, 1 unmixed) using 3MM10 - Mixing Modules- Solar thermal integration for DHW generation usingSM10 - Solar Thermal Module- Integration of a low loss header using WM10 - Low LossHeader Module- Cascade up to 16 boilers using up to 4 MCM10 - MultiBoiler Cascade Modules.- DHW preparation including control of a DHWrecirculation pumpLogamax plus GB142 applications manual 04.20171THU 06.07. 2011 4:45pmControl featuresRoom271.9 F3411 1098765Fig.9 Description of the RC35 room control1:2:3:4:5:6:7:8:9:10:11:Automatic mode (switching program)Continuous heating (day temperature)Permanently reduced (night temperature)DHW single charge buttonChange temperature temporaryBackShow dataSet day or night temperatureSet current dateSet current timeOpen User menuTechnical specifications are su