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 UPC Chapter 2

2 results

UPC 2006 203.0, 801.1 UPC 2012 203.0, 801.1 UPC 2015 203.0, 801.2

Topic: Air Gap

We are making medical instrument washer to be installed in Hospital. We are installing the 2" drainpipe 1" over the flood level to have the requested air gap. With this installation, we observe at some customer water splashing on the floor during drainage. We are looking at solution to avoid this issue.
Can we install a larger pipe over the drain piping that go inside the floor sink. This larger pipe will let air go into the drain pipe and avoid any chance of backflow into the washer. (see attachment)
The larger pipe could be attached to the drain piping or the floor sink.

Section 806.1 of the 2015 Uniform Plumbing Code requires sterile equipment such as stills, sterilizers, and similar equipment water and waste and used for sterile materials to be drained through an airgap. By definition an airgap for drainage is the “unobstructed vertical distance through the free atmosphere between the lowest opening of the appliance to the flood level rim of the receptor. The attached drawing of the appliance drain with a funnel to prevent splashing does not meet the definition of an airgap and would not be code compliant.

UPC 2015 204.0, 908.2

Topic: Horizontal Wet Venting

1. Does a horizontal wet vent system need to include a full bathroom group?
2. Can a toilet be horizontally wet vented from a single shower, bathtub, or lav?
Comment
We have had plumbing inspectors make us change how we have run our horizontal wet vents. Some inspectors will call us on the fact that we cannot use a horizontal wet vent system on a powder bathroom since it does not include a bathing unit and therefore doesn't qualify as a bathroom group.
I have drawn 6 diagrams of different horizontal wet vent systems that we have had inspectors make us change. I would like you to review them to make sure they comply with the requirements for horizontal wet venting.

We want to share the results with the local building officials so we all have the same understanding of horizontal wet venting design.

1. No. By definition of Bathroom Group “any combination.” of fixtures may be served by the horizontal wet vent. A water closet and a lavatory is a combination of fixtures. Lavatories will always be vented by a dry vent because the traps are above the floor and may serve as the dry vent for the system.
2. Yes. Same as #1. The dry vent connection to the wet vent shall be an individual vent for the bidet, shower, or bathtub. If you are using a bidet, shower or a bathtub as the dry vent you must follow sections 905.2 and 905.3 for the connection of the vent to the wet vent.
Note: All drawings appear to be code compliant, but remember that the AHJ does have the final say.

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