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PAGES: 76
SPACE HEATING HANDBOOK
CONTENTS
1. BASIC CONCEPTS
Heat transfer 1-3
Convection 1-3
Conduction 1-3
Radiation 1-3
Building heat loss and insulation 1-4
Combustion
Process of combustion 1-5
Requirements for combustion 1-5
Composition and combustion of
natural gas 1-5
Complete and incomplete combustion1-5
Controlled and explosive combustion 1-6
Odorants 1-6
Flammability limits 1-7
2. PRINCIPLES OF COMBUSTION HEATERS
Orifices 2-7
A good burner flame 2-7
Flashback and extinction pop 2-7
Burner operation at high altitude 2-7
Heat exchangers 2-8
Indirect-fired 2-8
Direct-fired 2-8
Ignition systems 2-9
Manual pilots 2-9
Automatic pilots 2-9
Carryover 2-9
Controls 2-9
Space-temperature controls 2-9
Thermostats 2-10
Location of thermostats 2-10
Thermostat adjustment 2-10
Safety controls 2-10
Flame-proving systems 2-10
Safety valves and gas valves 2-11
Solenoid valves 2-11
Hot-wire valves 2-11
Motorized valves 2-12
Diaphragm valves 2-12
High-temperature limit controls 2-13
Indirect-fired systems 2-13
Gas-pressure regulators 2-13
Proving switches 2-13
Venting systems 2-14
Flue products 2-14
Flue collectors 2-14
Vent dampers 2-14
Gravity and power venting 2-14
Multiple venting 2-14
3. GENERAL APPLICATION AND SELECTION CRITERIA
Duct systems for unit heaters 3-7
Duct furnaces 3-7
Combustion air 3-7
Duct systems 3-8
Air-flow & heat-distribution
considerations 3-8
By-pass ducts 3-8
Insulation 3-8
Controls 3-8
Gas-control systems 3-8
Drying applications 3-9
Packaged units 3-10
Combustion air 3-10
Duct systems 3-10
Insulation 3-10
Filter requirements 3-10
Heating-only use 3-10
Sizing 3-10
Pilot ignition 3-10
Gas-control systems 3-11
Air controls 3-11
Heating and/or makeup-air use 3-11
Makeup air 3-11
Sizing 3-11
Pilot ignition 3-11
Gas-control systems 3-11
Air controls 3-12
Use with cooling systems 3-12
Mechanical cooling 3-12
Evaporative cooling 3-12
Direct-fired combustion 3-13
Makeup air 3-13
Combustion/dilution air 3-13
Duct systems 3-13
Exhaust/relief 3-13
Makeup-air-only 3-13
Sizing 3-13
Process makeup air 3-13
Building makeup air 3-14
Gas controls 3-14
Air controls 3-15
Heat Physics
The nature of heat
Temperature 1-1
Temperature scales 1-1
Temperature conversion formulas 1-2
Heat quantity 1-2
Measuring heat quantity 1-2
The calorie 1-2
The British Thermal Unit 1-3
Gas measurement
Volume 1-7
Pressure 1-7
Specific gravity 1-7
Heat content 1-8
Heating value 1-8
Three basic types of heaters
Indirect-fired heaters 2-1
Direct-fired heaters 2-1
Infrared radiant heaters 2-1
High intensity 2-2
Low intensity 2-2
Relative efficiencies 2-2
Basic system components
Gas burners 2-3
Yellow-flame burners 2-3
Blue-flame (Bunsen) burners 2-3
Atmospheric burners 2-4
Power burners 2-5
Forced draft and induced draft 2-5
Burner designs 2-5
Indirect-fired 2-5
Direct-fired 2-6
Infrared 2-6
High-intensity 2-6
Low-intensity 2-6
Selection considerations
Fuel availability 3-1
Occupancy 3-1
Building function 3-1
Application and equipment considerations
Indirect-fired combustion 3-1
Vent systems 3-1
Combustion air 3-1
Unit heaters 3-2
Fans and blowers 3-3
Location 3-3
Sizing 3-3
Typical air throw (unit heaters) 3-4
Multiple-unit systems 3-5
Paddle fans 3-5
Controls 3-5
Pilot-ignition systems 3-6
Gas-control systems 3-6
Unit heaters in low ambient
temperatures 3-6
Heating- and makeup-air use 3-15
Sizing 3-15
Gas controls 3-15
Air controls 3-15
Heating units with cooling systems 3-15
Mechanical cooling 3-15
Evaporative cooling 3-15
Infrared heating 3-16
Combustion air 3-17
Exhaust/relief 3-17
High-intensity 3-17
Sizing 3-18
Location 3-18
Whole building or spot heating 3-18
Controls 3-18
Low-intensity 3-18
Sizing 3-18
Location 3-18
Controls 3-18
Whole-building or spot heating 3-18
Example applications
Indirect-fired heating 3-19
Unit heaters 3-19
Manufacturing plant 3-19
Greenhouse 3-19
School building 3-20
Duct Furnaces 3-20
Commercial 3-20
Packaged systems 3-21
Manufacturing, heating only 3-21
Manufacturing, heating and
makeup-air with cooling 3-21
Separated combustion 3-22
Direct-fired combustion 3-23
Kitchen makeup air 3-23
Factory heating & makeupair 3-23
Infared radiation 3-24
High intensity 3-24
Manufacturing plant 3-24
Spot heating 3-24
Low intensity 3-25
Whole-building heating 3-25
Assembly-line heating 3-26
4. TECHNICAL GIUDE
Optimizing distribution systems 4-7
Optimum forced-air equipment sizing 4-7
Optimum infrared equipment sizing 4-7
Zoning 4-7
Cost/benefits 4-7
Optimum equipment location 4-7
Coverage 4-7
Optimum duct system 4-8
Control system requirements 4-8
Selecting equipment 4-8
Safety and maintenance
Standards, codes and testing 3-27
Industry standards 3-27
ANSI 3-27
CSA 3-17
Codes 3-27
National Fire Protection
Association 3-27
National Fuel Gas Code 3-27
Insurance codes 3-27
Certification testing 3-27
AGA 3-27
UL 3-28
ETL 3-28
CGA 3-28
Independent labs 3-28
Local code requirements 3-28
Clearances 3-28
Cautions and limitations 3-28
Hazard intensity levels 3-28
Common precautionary
statements 3-29
Miscellaneous precautions 3-29
General safety tips 3-29
Maintenance 3-30
Good housekeeping 3-30
General maintenance requirements 3-30
Inspection 3-30
Forced-air equipment 3-30
Radiant heaters 3-31
General troubleshooting guide 3-31
Troubleshooting chart 3-32
Heat system selection
Heat requirements 4-1
Design temperatures 4-1
Degree days 4-1
Infiltration 4-2
Ventilation 4-2
Makeup-air requirements 4-3
Heat loss formulas and U-Factors 4-4
U-Factor table 4-4
Air-flow requirements 4-5
Ventilation & makeup-air 4-5
Entering-air temperature 4-5
Temperature rise 4-5
Static pressure 4-5
Relief, exhaust 4-6
Technical data
Pipe sizes 4-9
Pipe pressure drops 4-9
Equivalent lengths of fittings & valves 4-10
Gas-meter flow time 4-10
Orifice/pressure tables
Natual gas 4-11
LP gases 4-12
Specific gravity for other gases 4-12
5. GLOSSARY
Space heating terms 5-1 to 5-4
INTRODUCTION
Natural gas is just one of the sources of heat energy available for space heating today; the others are fuel oil, manufactured gas, propane, butane, coal, electricity, and wood. Of all the available fuels, natural gas offers the best combination of convenience, availability, economy, cleanliness, non-pollution characteristics, and reliability of supply. As a result, it has become a most widely used fuel for commercial and industrial (and residential) space heating in the U.S. and other industrial nations. The wide use of natural gas in the United States has come about in just a little over a
century. Although it is possible to trace humankind’s awareness of the existence of natural gas back about 2,500 years to the ancient Chinese (who piped it to the point of use through bamboo poles), modern natural-gas history in the United States did not begin until 1821. It was then that William Hart dug the first gas well (27 feet deep) outside Fredonia, New York. For the next 37 years, use of natural gas and the drilling of wells spread through western New York State and Pennsylvani, and northern Ohio and Indiana. The young natural gas industry grew quickly, and by 1900, there were natural gas wells in 17 states. Today, only a few states do no have any gas wells within their borders, but all have natural gas available because of the
several million miles of gas transmission and distribution lines that now crisscross the entire country. This vast underground network and the
transportability of natural gas account for the convenience and reliability of natural gas as a fuel. Only electricity approaches the convenience and reliability of pipe delivered natural gas, but it is more costly and more subject to interruption due to weather. Coal, although less expensive, is awkward to transport and deliver to space heating equipment and more difficult to control to get the uniform heating expected of today’s space heating equipment. Although fuel oil competes with natural gas in price and in controllability at the space heater, it must be transported and delivered by truck or rail and stored on site. Propane, although generally available, is used where natural-gas lines are not in place and is stored on site. All factors considered, natural gas offers the best combination of characteristics.
This handbook deals strictly with the heating of commercial and industrial buildings and facilities. It is also limited to space heating with natural gas and propane gas. For the most part, natural gas and propane gas are similar, and most of the technical text applies to both. Where major differences exist, propane will be mentioned; otherwise, the reader may assume that both are meant even if only natural gas is mentioned for convenience and brevity of expression.
