Heating Systems Troubleshooting & Repair Maintenance Tips & Forensic Observations John Certuse, P.E. INDUSTRIAL PRESS, INC. Industrial Press, Inc. 32 Haviland Street, Suite 3 South Norwalk, Connecticut 06854 Phone: 203-956-5593 Toll-Free in USA: 888-528-7852 Fax: 203-354-9391 Email: [email protected] Author: John Certuse, P.E. Title: Heating Systems Troubleshooting & Repair: Maintenance Tips & Forensic Observations Library of Congress Control Number: 2019936359 © by Industrial Press. All rights reserved. Published in 2019. Printed in the United States of America. ISBN (print): 978-0-8311-3640-6 ISBN (ePDF): 978-0-8311-9518-2 ISBN (ePUB): 978-0-8311-9519-9 ISBN (eMOBI): 978-0-8311-9520-5 Editorial Director/Publisher: Judy Bass Copy Editor: Judy Duguid Compositor: Patricia Wallenburg, TypeWriting No part of this book may be reproduced or transmitted in any form or by any means, elec- tronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher. Limits of Liability and Disclaimer of Warranty The author and publisher make no warranty of any kind, expressed or implied, with regard to the documentation contained in this book. All rights reserved. industrialpress.com ebooks.industrialpress.com 10 9 8 7 6 5 4 3 2 1 PREFACE Most technicians leaving trade school are typically focused on passing a license exam that, for the most part, addresses the installation of new equipment. The fact is, how- ever, that over the course of their career, most of the work they perform is not install- ing new equipment but, rather, repairing and maintaining older, existing systems. In fact, some technicians may find themselves servicing equipment that is more than 100 years old (Figure P-1). FIGURE P-1 Early Turn-of-the-Century Boiler Still in Use Today Heating Systems Troubleshooting & Repair: Maintenance Tips & Forensic Observations was written for those technicians installing new systems as well as for those keeping older systems in proper working order. This book addresses many issues, from boiler and furnace design to maintenance requirements of both the appliance and the entire system heating the home. It also addresses the need to change attitudes toward maintenance. xiii xiv PREFACE Prevailing Attitudes It has been said that we live in a “disposable society” where older appliances are rarely repaired, with service technicians preferring to replace equipment needing more advanced repairs. This attitude extends to home heating appliances that, due to the fault of many, the homeowner included, are often left in service until small repairs are no longer sufficient and the appliance requires replacement. Then there is the commonly repeated philosophy of “If it ain’t broke, don’t fix it.” Following this philosophy means only addressing repairs after equipment has broken down and can result in unexpected consequences. Where does the responsibility fall for boiler and furnace failures? That responsi- bility belongs to everyone involved—but to different degrees. On rare occasions, it is the manufacturer who is responsible, but more often it is the homeowners and those employed to maintain these appliances. The manufacturing and installation of an appliance are onetime occurrences, performed and then done. Required preventative maintenance actions, however, are ongoing and needed throughout the service life of the appliance. The Importance of Preventative Maintenance Residential boilers and furnaces are designed to run efficiently and reliably through- out their design life. But to achieve longevity of life and efficient operation, the appli- ance and system must be maintained through a regimen of preventative maintenance actions throughout the equipment’s service life. It is these preventative maintenance actions that determine the quality of the service life of the appliance as well as the likelihood of unexpected equipment breakdown, costly equipment replacement, and building damage. A Team Effort This book is intended to familiarize new service technicians of the overall mainte- nance requirements of a heating system and to help them to realize that maintenance is not limited to one particular component of a system without regard to others. It’s a team effort to keep home heating appliances running safely, efficiently, and reliably. The team includes both the manufacturers of appliances that provide training and replacement components and the local service organizations that install these appliances and perform needed repairs. More importantly, this team includes the homeowner or building owner who must also support the service technician’s rec- ommendations by scheduling annual maintenance allowing the technician to perform needed maintenance repairs. In the end, each party needs the other to make sure a residential heating appli- ance is maintained to a level where it can not only achieve the intent of its original design but also potentially exceed these expectations in performance and longevity. PREFACE xv The purpose of this book is not to replace existing manufacturer’s maintenance directives but rather, to make the technician aware of their importance and the need to be knowledgeable of the appliance’s ongoing maintenance needs throughout its service life. John Certuse, P.E. May 2019 CONTENTS Preface ..........................................................xiii Acknowledgments ................................................ xvii CHAPTER 1 Maintenance Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Are You Really Maintaining Your Equipment or Just Fixing It? ............... 1 The Consequences of “Run It Until It Doesn’t Work Anymore” ............... 1 Installation to Code and Ongoing Maintenance ........................... 2 Three Levels of Maintenance ......................................... 3 The Maintenance Mix ............................................... 5 P-F Curves and P-F Intervals—Predicting the Time to Failure ............... 6 Furnace and Boiler Life Expectancy .................................... 6 Why Replace a Boiler or Furnace? ..................................... 7 The Degradative Effects of Ignored Preventative Maintenance ............... 11 The Building or Homeowner, the Technician, and the Manufacturer Working Together! ................................ 13 Reference ........................................................ 14 CHAPTER 2 Heating System Types and Preventative Maintenance 15 Older Systems Still in Use Today ..................................... 16 Gravity Hot Air ................................................ 16 Gravity Hot Water .............................................. 18 Steam ........................................................ 19 Modern Heating Systems ........................................... 22 Forced Hot Water (Hydronic) ..................................... 22 Forced Hot Air ................................................. 23 v vi CONTENTS The Heat Pump System .......................................... 24 Hydro Air ..................................................... 24 Preventative Maintenance Pertaining to the Heat Distribution System ........ 24 Forced Hot Water System Maintenance .............................. 25 Steam System Maintenance ....................................... 27 Forced Hot Air Ductwork System Maintenance ....................... 29 Air-Conditioning Condensate System Maintenance .................... 30 References ....................................................... 32 CHAPTER 3 Installation to Code and Ongoing Maintenance . . . . . 33 Heating System Design ............................................. 33 Heat Load Determination ........................................... 33 Hydronic Heating System Design ..................................... 34 Appliance Placement ............................................... 34 Clearances to Combustibles........................................ 34 Confined Space of Installation...................................... 35 Chimneys and Direct venting ........................................ 39 Masonry....................................................... 39 Metal Flues .................................................... 39 venting and Appliance Categories..................................... 40 Direct venting .................................................... 41 Practical Considerations Addressing the Installation of Heating Systems....... 44 Boiler and Furnace Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Access for Maintenance and Replacement............................. 44 Placement of Ductwork Diffusers and Baseboards ...................... 45 Freezing ....................................................... 46 References ....................................................... 47 CHAPTER 4 Boiler Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Boiler Construction ................................................ 49 Boiler Configuration—Wet Base and Dry Base Boilers .................... 50 Cast-Iron Sectional Boilers .......................................... 50 Cast-Iron Boiler Joining Methods .................................... 53 Section Gaskets ................................................... 53 Section Push Nipples .............................................. 54 Section Sealant, Rope Gaskets, or Sealing Cord .......................... 54 CONTENTS vii Burner Type and Flame Geometry and Orientation Overview ............... 55 Tankless Heat Exchangers and Gaskets ................................ 57 Boiler Heat Exchanger Design Configurations ........................... 58 vertical Fire-Tube Cast-Iron Boiler (“Snowman”) ...................... 59 Power Burner–Fired (Oil or Gas Conversion–Fired Boiler), Cast-Iron Sectional Boiler—Wet Base ............................. 61 Steel Fire-Tube (Oil or Gas Conversion–Fired) Boiler—Dry Base ......... 62 Power Burner–Fired (Oil or Gas Conversion–Fired Boiler), Cast-Iron Sectional Boiler—Dry Base ............................. 65 Cast-Iron, Gas-Fired Boiler—Dry Base .............................. 66 Cast-Iron, Gas-Fired, Horizontal Sectional Boiler—Dry Base ............ 68 Copper Tube–Aluminum-Finned, Low-Water-volume, Gas-Fired Boiler—Dry Base .................................... 69 Coiled Copper Tube–Aluminum-Finned, Low-Water-volume, Gas-Fired Boiler .............................................. 71 Spiral, Low-Water-volume, Stainless-Steel, Gas-Fired, Condensing Boiler... 72 Cast Aluminum ................................................. 74 CHAPTER 5 Residential Furnace Design . . . . . . . . . . . . . . . . . . . . . 83 Warm Air System Types............................................. 83 Natural (Gravity) Hot Air Circulation................................ 83 Forced Hot Air Circulation ........................................ 83 Furnace Designs, Natural (Gravity) Hot Air ............................. 83 Floor or Wall Furnace ............................................ 84 Furnace Designs, Forced Hot Air...................................... 85 Airflow Direction.................................................. 85 Upflow Furnace ................................................. 85 Downflow Furnace............................................... 85 Horizontal ..................................................... 86 Energy Sources.................................................... 86 Electric Furnaces and Heat Pumps .................................. 87 Hydro Air...................................................... 88 Combustion Furnaces............................................... 89 Counter-Flow and Parallel-Flow Heat Transfer .......................... 89 Heat Exchanger Flow Path Length ................................. 90 Furnace Cabinet–Heat Exchanger Orientation......................... 90 Oil Furnace Design .............................................. 91 viii CONTENTS Gas Furnace Design.............................................. 95 Soot Damage Caused by Malfunctioning Furnaces ....................... 102 Is it Really Soot from the Furnace? ................................... 102 Origins of Soot and Products of Combustion Other Than a Broken Heat Exchanger .................................................. 103 Heat Exchanger Leaks and Cracks ................................. 104 Detecting the Presence of Leaks..................................... 105 Fan Test ...................................................... 105 Flame Test .................................................... 106 Product-of-Combustion Gas Detector .............................. 107 Smoke Candle Test ............................................. 108 Tracer Gas .................................................... 108 Gaining Access to the Leak (with the Furnace Still Assembled)............. 109 Access to the Heat Exchanger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Common Locations of Heat Exchanger Failures....................... 110 visual and Other Inspection Methods............................... 115 References ...................................................... 123 CHAPTER 6 The Oil Burner and Fuel System . . . . . . . . . . . . . . . 125 Oil Burner Design ................................................ 125 Basic Components ............................................. 126 The Burner Body–Fan Assembly ................................... 127 The Fuel System ............................................... 129 The Ignition Transformer and Electrodes ............................ 130 Air Path and Air Adjustment ..................................... 131 Different Manufacturers ......................................... 132 Annual and Required Maintenance ................................... 134 Filters ....................................................... 134 Strainers ..................................................... 135 Nozzles ...................................................... 136 Electrodes .................................................... 138 The Primary Control ............................................ 139 The Firesides Cleaning .......................................... 141 The Combustion Performance Test ................................. 143 Typical Flame Retention Oil-Fired Burner Appliance Readings .......... 149 Service Records .................................................. 150 Combustion Performance Test Data ................................ 150 CONTENTS ix Service History................................................. 151 CHAPTER 7 The Gas Burner System . . . . . . . . . . . . . . . . . . . . . . 155 The Air-Gas Mix ................................................. 155 Ignition Systems ................................................. 156 The Standing Pilot System ....................................... 157 Energy Losses Due to Pilot Flame Usage ............................ 158 Electronic Ignition ............................................. 159 Burner Design and Construction .................................... 166 Atmospheric or Tube Type ....................................... 166 Premix ....................................................... 170 Gas Burner Maintenance .......................................... 171 Appliance Maintenance ......................................... 171 Gas Pressure Check ............................................. 172 Burner Tube Inspection .......................................... 173 Combustion Chamber and Refractories ............................. 175 Combustion Performance Testing—Gas-Fired Appliances ................ 176 Carbon Monoxide in Combustion Gases............................. 177 Ambient Carbon Monoxide Measurement and Levels .................. 177 Appliance Combustion Parameters ................................. 178 References ...................................................... 182 CHAPTER 8 Soot Damage and Poor Indoor Air Quality in Homes . 183 Indoor Air Quality ............................................... 183 It’s Soot! What Is the Cause?........................................ 186 Conventional Failure Diagnosis.................................... 186 Common Locations of Accumulated Soot.............................. 192 Ghosting Soot Accumulations..................................... 192 Depressurization-Induced Combustion Reentry......................... 193 Advancements in Housing Material ................................ 194 Building Envelope Tightness ..................................... 194 Creation of a Negative Pressure Within the Building Envelope ........... 195 Combustion Appliance Issues and Depressurization.................... 196 Backdraft—Depressurization Reentry at the Appliance ................. 196 Depressurization Reentry Due to the Proximity of Discharge ............ 197 Paths of Reentering Emissions Flow ............................... 199