UL 795-2016 UL Standard for Safety Commercial-Industrial Gas Heating Equipment (Eighth Edition).pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 795 Commercial-Industrial Gas Heating Equipment STANDARD FOR SAFETYUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRIGHTED MA

2、TERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Commercial-Industrial Gas Heating Equipment, UL 795 Eighth Edition, Dated December 2, 2016 Summary of Topics This new edition of UL 795 includes direct vent revisions and removal of t

3、est number references. The revisions are substantially in accordance with Proposal(s) on this subject dated September 2, 2016. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form by any means, electronic, mechanical photocopyin

4、g, recording, or otherwise without prior permission of UL. UL provides this Standard as is without warranty of any kind, either expressed or implied, including but not limited to, the implied warranties of merchantability or tness for any purpose. In no event will UL be liable for any special, incid

5、ental, consequential, indirect or similar damages, including loss of prots, lost savings, loss of data, or any other damages arising out of the use of or the inability to use this Standard, even if UL or an authorized UL representative has been advised of the possibility of such damage. In no event

6、shall ULs liability for any damage ever exceed the price paid for this Standard, regardless of the form of the claim. Users of the electronic versions of ULs Standards for Safety agree to defend, indemnify, and hold UL harmless from and against any loss, expense, liability, damage, claim, or judgmen

7、t (including reasonable attorneys fees) resulting from any error or deviation introduced while purchaser is storing an electronic Standard on the purchasers computer system. DECEMBER 2, 2016 UL 795 tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION

8、FROM UL DECEMBER 2, 2016 UL 795 tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL DECEMBER 2, 2016 1 UL 795 Standard for Commercial-Industrial Gas Heating Equipment First Edition November, 1952 Second Edition October, 1

9、964 Third Edition April, 1973 Fourth Edition June, 1994 Fifth Edition July, 1999 Sixth Edition October, 2006 Seventh Edition April, 2011 Eighth Edition December 2, 2016 This UL Standard for Safety consists of the Eighth Edition. The Department of Defense (DoD) has adopted UL 795 on January 27, 1992.

10、 The publication of revised pages or a new edition of this Standard will not invalidate the DoD adoption. Comments or proposals for revisions on any part of the Standard may be submitted to UL at any time. Proposals should be submitted via a Proposal Request in ULs On-Line Collaborative Standards De

11、velopment System (CSDS) at https:/. ULs Standards for Safety are copyrighted by UL. Neither a printed nor electronic copy of a Standard should be altered in any way. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive property

12、 of UL. COPYRIGHT 2016 UNDERWRITERS LABORATORIES INC.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL DECEMBER 2, 2016 COMMERCIAL-INDUSTRIAL GAS HEATING EQUIPMENT - UL 795 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTH

13、ER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .6 2 Glossary .6 3 Units of Measurement 14 4 Undated References .14 5 Components 14 CONSTRUCTION MECHANICAL 6 General.14 7 Corrosion Protection .15 8 General Components and Devices .16 CONSTRUCTION ELECTRICAL 9

14、General.16 10 Servicing and Adjustment 17 11 Electrical Enclosures 17 12 Field Wiring Connections 26 13 Internal Wiring30 14 Separation of Circuits .34 15 Mounting of Components 35 16 Motors and Motor Overcurrent or Overload Protection.36 17 Overcurrent Protection of High-Voltage Control-Circuit Con

15、ductors40 17.1 General .40 17.2 Tapped high-voltage control circuits 40 17.3 Overcurrent-protective devices .41 18 Overcurrent Protection of Transformers42 18.1 High-voltage transformers .42 18.2 Thermal protection .42 18.3 Low-voltage transformers43 18.4 Overcurrent protective devices .43 19 Switch

16、es and Controllers 44 20 Capacitors .45 21 Electrical Insulating Material46 22 Spacings High-Voltage Circuits .46 23 Spacings Low-Voltage Circuits47 24 Accessibility of Uninsulated Live Parts.48 25 Bonding For Grounding50 CONSTRUCTION BURNER ASSEMBLIES 26 General53 27 Combination Gas-Oil Burner Asse

17、mblies 54 CONSTRUCTION BOILERS, FURNACES AND HEATERS 28 General55 29 Accessibility 56 DECEMBER 2, 2016 COMMERCIAL-INDUSTRIAL GAS HEATING EQUIPMENT - UL 795 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 30Baffles.56 31 Limit Controls 56 31

18、.1 General .56 31.2 Liquid level limit controls boilers 57 31.3 Pressure limit controls boilers 58 31.4 Temperature limit controls boilers.59 31.5 Temperature limit controls warm air furnaces and heaters .60 32 Installation of External Controls and Fittings on Boilers 60 33 Flue Dampers, Draft Regul

19、ators, and Draft Hoods 61 34 Bleeds and Vents .62 35 Bases .63 36 Heating Surfaces and Combustion Chambers 63 37 Radiation Shields .64 38 Materials in Air Handling Compartments .64 39 Casings .65 40 Fuel Lines and Components .66 41 Flue Collars 66 42 Air Filters 66 PERFORMANCE 43 General66 44 Test I

20、nstallations68 44.1 Floor-mounted devices 68 44.2 Suspended furnaces 68 44.3 Unit heaters .72 44.4 Test ducts for furnaces .73 45 Test Methods 73 45.1 Firing conditions73 45.2 Temperature measurements .74 46 Burner Assembly Tests 78 46.1 Combustion test78 46.2 Combustion air failure test.80 46.3 Und

21、ervoltage test 81 46.4 Power interruption test 82 46.5 Pilot supervision test83 46.6 Ignition, gas-electric high tension test .83 46.7 Ignition, gas-electric hot-wire Undervoltage test 84 46.8 Ignition, gas-electric hot-wire Igniter endurance test.85 46.9 Ignition, gas-electric hot-wire Temperature

22、test .85 46.10 Ignition, multiple burner test 86 46.11 Delayed ignition test .86 47 Operation Tests 87 47.1 Device limit control cutout test .87 47.2 Continuity of operation for furnaces and heaters test .88 47.3 Air ow of horizontal furnaces test88 48 Temperature Tests89 48.1 General .89 48.2 Conti

23、nuous operation test .93 48.3 Blocked inlet of furnaces and heaters test .93 48.4 Fan failure of furnaces and heaters test .93 48.5 Blocked outlet of furnaces and duct-connected heaters test .94 49 Low Water Cutoff of Boilers Test .94 DECEMBER 2, 2016 COMMERCIAL-INDUSTRIAL GAS HEATING EQUIPMENT - UL

24、 795 4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 50 Short-Circuit Test .95 51 Overload Test, High-Voltage Transformers.97 52 Burnout Test, High-Voltage Transformers 98 53 Dielectric Voltage-Withstand Test .99 54 Draft Hood Equipped Devi

25、ces .100 54.1 Blocked outlet test 100 54.2 Downdrafts and updrafts test .100 54.3 Spillage test 101 54.4 Draft hood strength test 103 54.5 Condensing-type devices 103 55 Blocked Outlet of Forced or Induced Draft Equipped Condensing Appliances Test.104 56 Direct Vent Tests 104 56.1 Direct vent system

26、 leakage test .104 56.2 Direct vent wind tests 106 56.3 Direct vent rain test .107 56.4 Direct vent load test .107 56.5 Direct vent impact test .108 57 Flame Test .111 58 Strain Relief Test 112 OUTDOOR-USE EQUIPMENT 59 General 112 60 Enclosures112 61 Field Wiring Connections .115 62 Wiring 115 63 Ou

27、tdoor-Use Equipment Tests 115 63.1 General 115 63.2 Rain test .116 63.3 Wind test.119 64 Gaskets 120 65 Chromic Acid Dropping Test 121 MANUFACTURING AND PRODUCTION TESTS 66 General 122 MARKINGS 67 General 123 INSTRUCTIONS 68 General 127 DECEMBER 2, 2016 COMMERCIAL-INDUSTRIAL GAS HEATING EQUIPMENT -

28、UL 795 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scope 1.1 These requirements apply to factory-built gas appliances having inputs of more than 400,000 Btu per hour, per individual combustion chamber which require ame fa

29、ilure and other precautions and which are intended primarily for commercial and industrial installation. The appliances covered by these requirements are comfort heating furnaces, heaters and gas-red boiler assemblies except watertube boilers having outputs of 10,000 pounds of steam per hour or more

30、. 1.2 These requirements also apply to all high pressure steam and high temperature water gas-red boiler assemblies regardless of Btu per hour input. 1.3 Gas-heating equipment covered by these requirements may be operated without a competent attendant being constantly on duty at the burners while th

31、e appliances are in operation. 1.4 Additional installation and operation requirements are available for central-heating gas appliances, oor furnaces, room heaters, unit heaters, and water heaters as dened by the National Fuel Gas Code, NFPA 54, and by the Liqueed Petroleum Gas Code, NFPA 58, as appl

32、icable. 2 Glossary 2.1 For the purposes of this Standard the following denitions apply. 2.2 AIR HEATER An indirect red vented appliance intended to supply heated air for space heating and other purposes, but not intended for permanent installation. 2.3 AIR SHUTTER An adjustable device for varying th

33、e size of the air inlet or inlets regulating primary or secondary air. 2.4 AIR SHUTTER, AUTOMATICALLY OPERATED An air shutter operated by an automatic control. 2.5 AIR SHUTTER, MANUALLY OPERATED An air shutter manually set and locked in the desired position. 2.6 APPLIANCE FLUE The ue passages within

34、 an appliance. 2.7 ALUMINUM COATED STEEL An aluminum coated steel in which the bond between the steel and the aluminum is an iron-aluminum alloy. 2.8 BAFFLE An object placed in an appliance to direct the ow of air or ue gases. 2.9 BASE The main supporting frame or structure of the assembly, exclusiv

35、e of legs. 2.10 BOILER A closed vessel in which water or some other liquid is heated or steam is generated or superheated, under pressure or vacuum, by direct application of heat. DECEMBER 2, 2016 COMMERCIAL-INDUSTRIAL GAS HEATING EQUIPMENT - UL 795 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHE

36、R REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 2.11 BOILER, HIGH PRESSURE STEAM A boiler in which steam is generated at a pressure higher than 15 psig (103 kPa). 2.12 BOILER, HIGH TEMPERATURE WATER A boiler intended for operation at a pressure exceeding 160 psig (1103 kPa) and at a temper

37、ature exceeding or at a temperature exceeding 250F (121C). 2.13 BOILER, HOT WATER A boiler that furnishes hot water at a pressure not exceeding 160 psig (1103 kPa) and at a temperature not exceeding 250F (121C). 2.14 BOILER, LOW PRESSURE STEAM A boiler in which steam is generated at a pressure not e

38、xceeding 15 psig (103 kPa). 2.15 BURNER GAS A device for the nal conveyance of the gas, or a mixture of gas and air, to the combustion zone. 2.16 BURNER, AUTOMATICALLY LIGHTED One where fuel to the main burner is normally turned on and ignited automatically. 2.17 BURNER, MANUALLY LIGHTED One where f

39、uel to the main burner is turned on only by hand and ignited under supervision. 2.18 BURNER HEAD, GAS That portion of a burner beyond the outlet end of the mixer tube which contains the ports. 2.19 CASING An enclosure forming the outside of the appliance, no parts of which are likely to be subjected

40、 to intense heat. 2.20 CHIMNEY CONNECTOR The pipe which connects a fuel burning appliance to a chimney. 2.21 COMBUSTIBLE MATERIAL Combustible material, as pertaining to materials adjacent to or in contact with heat producing appliances, chimney connectors and vent connectors, steam and hot water pip

41、es, and warm air ducts, means material made of or surfaced with wood, compressed paper, plant bers, or other material that will ignite and burn. Such material shall be considered as combustible even though ameproofed, re retardant treated, or plastered. 2.22 COMBUSTION As used herein, the rapid oxid

42、ation of fuel accompanied by the production of heat, or heat and light. Complete combustion of a fuel is possible only in the presence of an adequate supply of oxygen. 2.23 COMBUSTION CHAMBER The portion of an appliance within which combustion occurs. 2.24 COMBUSTION DETECTOR That part of a primary

43、safety control which is responsive directly to ame properties. 2.25 COMBUSTION PRODUCTS Constituents resulting from the combustion of a fuel with the oxygen of the air, including the inerts, but excluding excess air. DECEMBER 2, 2016 COMMERCIAL-INDUSTRIAL GAS HEATING EQUIPMENT - UL 795 7UL COPYRIGHT

44、ED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 2.26 CONDENSATE The liquid which separates from a gas, including ue gases, due to a reduction in temperature. 2.27 CONTROL A device designed to regulate the fuel, air, water, or electrical supply to the co

45、ntrolled equipment. It may be automatic, semi-automatic, or manual. 2.28 CONTROL INPUT, COMBUSTION A control which automatically regulates the ring rate at predetermined air-fuel ratio in accordance with load demand. It may be a type which positions the air and fuel supplies for low re and for high

46、re as required to meet the load demands, or it may be a modulating type which gradually varies the air and fuel supplies within limits to meet the load demand. 2.29 CONTROL, HIGH LIMIT A protective (safety) control that is responsive to changes in pressure, temperature, liquid level, or ow. It is to

47、 be set beyond the intended operating range of the controlled equipment to limit its operation. This control may be electrical or mechanical in nature. 2.30 CONTROL, OPERATING LIMIT A limit control to start fuel input according to demand and to stop fuel input on satisfaction of demand. An operating

48、 limit control may be electrical or mechanical in nature. 2.31 CONTROL, PROTECTIVE (SAFETY) Automatic controls and interlocks (including relays, switches, and other auxiliary equipment used in conjunction with a safety control circuit) which are intended to prevent operation of the controlled equipm

49、ent under conditions not anticipated by the design. A control intended to prevent the risk of electric shock, re, or injury to persons during abnormal operation of the appliance. An example would be a water temperature limit control. A protective control always provides Type 2 action. (See 2.93). 2.32 CONTROL, PRIMARY SAFETY An automatic control that monitors the operation of a gas-red or an oil-red burner. It no