Answers and Analysis

This knowledge base, updated to include the analyses from the 2003 through the most recent editions of the Uniform Plumbing and Mechanical Codes, continues to be a premier source for engineers, inspectors, students, contractors and tradesmen. Questions come from a broad base of users, and answers are informal interpretations of the Codes provided by a committee of code officials and special experts - they are clearly stated and to the point. This updated site combines the most pertinent analyses from the previous manual and presents them together with those based on the most recent publications of the Uniform Codes. This makes the Answers and Analysis database one of the most valuable tools you as a member can access wherever you have an internet connection.

The Answers and Analysis tool makes it easy to search for relevant questions and answers, either based on keywords or specific sections/chapters of the code. To find questions related to specific topics, type in the keyword(s), select the code and the year and click "Search". To search for questions related to a specific section, type the section in the Section field and click "Search". To search a specific chapter or appendix, select either the UPC or UMC Table of Contents, and select the chapter/appendix from the list.

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UPC Table Of Contents

Chapter	Title
1	Administration
2	Definitions
3	General Regulations
4	Plumbing Fixtures and Fixture Fittings
5	Water Heaters
6	Water Supply and Distribution
7	Sanitary Drainage
8	Indirect Wastes
9	Vents
10	Traps and Interceptors
11	Storm Drainage
12	Fuel Gas Piping
13	Health Care Facilities and Medical Gas and Medical Vacuum Systems
14	Firestop Protection
15	Alternate Water Sources for Nonpotable Applications
16	Nonpotable Rainwater Catchment Systems
17	Referenced Standards
Appendix A	Recommended Rules for Sizing the Water Supply System
Appendix B	Explanatory Notes on Combination Waste and Vent Systems
Appendix C	Alternate Plumbing Systems
Appendix D	Sizing Storm Water Drainage Systems
Appendix E	Manufactured/Mobile Home Parks and Recreational Vehicle Parks
Appendix F	Firefighter Breathing air Replenishment Systems
Appendix G	Sizing of Venting Systems
Appendix H	Private Sewage Disposal Systems
Appendix I	Installation Standards
Appendix J	Combination of Indoor and Outdoor Combustion and Ventilation Opening Design
Appendix K	Potable Rainwater Catchment Systems
Appendix L	Sustainable Practices
Appendix M	Sustainable Practices
Appendix N	Impact of Water Temperature on The Potential for Scalding and Legionella Growth

UMC Table Of Contents

Chapter	Title
1	Administration
2	Definitions
3	General Requirements
4	Ventilation Air
5	Exhaust Systems
6	Duct Systems
7	Combustion Air
8	Chimneys and Vents
9	Installation of Specific Appliances
10	Boilers and Pressure Vessels
11	Refrigeration
12	Hydronics
13	Fuel Gas Piping
14	Process Piping
15	Solar Energy Systems
16	Stationary Power Plants
17	Referenced Standards
Appendix A	Residential Plans Examiner Review Form for HVAC System Design
Appendix B	Procedures to be Followed to Place Gas Equipment in Operation
Appendix C	Installation and Testing of Oil (Liquid) Fuel-Fired Equipment
Appendix D	Fuel Supply: Manufactured/Mobile Home Parks and Recreational Vehicle Parks
Appendix E	Sustainable Practices
Appendix F	Geothermal Energy Systems
Appendix G	Sizing of Venting Systems and Outdoor Combustion and Ventilation Opening Design
Appendix H	Example Calculation of Outdoor Air Rate

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Questions matching UMC Chapter 10

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UMC 2009 1006 UMC 2012 1006.1 UMC 2015 1005.2 UMC 2018 1005.2

Topic: Safety or Relief Valve Discharge

1. Does section 1005.2 (3) apply to the discharge piping from steam pressure safety valves (PSV)?

No, this requirement is specifically applicable to section 1005.2 of the 2015 Uniform Mechanical Code which pertains to boilers and pressure vessels and the termination of their listed pressure relief valves. Safety and relief valves shall not discharge so as to be a hazard, a potential cause of damage or otherwise a nuisance. High pressure must be vented to the outside of the structure. Low pressure can discharge to the drainage system; the installation must conform to the Uniform Plumbing Code.

The termination of pressure steam valves should be consistent with UMC 1005.4 due to the hazard potential created by discharge of steam or as specified by the manufacturer of the valve and or boiler. Additionally sections 904.6 and 904.6.1 of the 2015 UMC also deal with relief valve termination. Section 904.6.1 when applied, should be cross referenced with section 1005.3 (Splash Shield) that states any operating temperature exceeding 212º F the discharge piping needs to be installed with a splash shield or centrifugal separator

UMC 2012 1010.1(1) UMC 2015 1009.1 UMC 2018 1009.1

Topic: Combustion Regulators — Safety Valves

1. Are these the safety shut-off gas valves?
2. Does it apply to natural gas heating hot water boilers?

Comment:
Code requires (2)temperature combustion regulators in series in heating hot water boilers.
Please provide a code interpretation/Substantiation.

1. Yes, every boiler requires proper control of the pressures and temperatures during its cycling process and the required combustion safety regulators would be considered safety valves that could either interrupt the fuel source or cause a cycle down that is caused by an unsafe boiler condition.
2. Yes, these requirements apply to natural gas fired boilers.