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 2

6 results

UMC 2003 216.0 see also Table 3-2 & 3-3 UMC 2006 216.0 see also Table 3-2 & 3-3 UMC 2009 216.0 see also Table 3-3 & 3-4 UMC 2012 216.0 see also Table 303.3(1) & 303.3(2)

Topic: Single Wall Gas Vents

1. Is 5/8 inch Type X gypsum wallboard considered a combustible per the UMC in reference to clearances from single-wall gas vents?

2. Would it be acceptable per the UMC to reduce the clearances between a single-wall gas vent and 5/8 inch Type X gypsum wallboard by applying paint to the wallboard?

1. Yes. Gypsum wallboard does not meet the definition of noncombustible as defined in Section 216.0.

2. No. Acceptable methods of clearance reduction can be found in Table 3-2 as per footnote 2 of Table 3-3 (Table 3-3 as per footnote 2 of Table 3-4, 2009).Other methods of clearance reduction would be considered an alternate method.

UMC 2006 502.0; 504.1 UMC 2009 502.0; 504.1 UMC 2012 207.0, 504.0

Topic: Exhaust Systems

Toilet room, dryer and domestic range exhausts are all defined as 'environmental air' in Section 207.0.
Is there any reason these 3 air streams cannot be ducted to a common exhaust duct riser served by a scavenger fan?
Comment:
In a 16-story residential high rise, the dryers are ventless and the laundry exhaust is from the room, not the dryer vent (no lint).

No. Sections 504.2 and 504.3 (2003/2006/2009/2012); 504.3 and 504.4 (2015) specifically requires domestic range exhaust systems and clothes dryer moisture exhaust systems be separate and distinct from each. In most cases the same types of environment air ducts could vent into a common riser. A clothes dryer moisture exhaust system would need to be installed as this is a residential high rise building and future occupants may not provide a ventless dryer. The dryer exhaust (either vented or ventless) releases lint during the process of drying the clothes into the atmosphere and the lint gathers in the duct picked up by the exhaust. If the bathroom exhaust is connected to the dryer exhaust the moisture would clog the system causing a fire hazard. Domestic range exhaust does capture and exhaust small amounts of grease laden vapors and would have an adverse effect when combined with moisture and lint. Ventless dryers are required to be provided with additional ventilation to the laundry room and the exhaust from that room shall be directly to the outside.

UMC 2009 609 UMC 2012 608.1 UMC 2015 203, 608.1 UMC 2018 203.0, 608.1

Topic: Air Moving System and Smoke Detectors

Do evaporator coolers fall under the regulated air moving systems that may require automatic shutoff under 608.1?

Yes. Evaporative cooling systems used to provide supply air to enclosed spaces of buildings fall under the 2018 Uniform Mechanical Code Section 608.1. It requires an automatic shutoff when the velocity of the supply air produced exceeds 2000 Cu. ft. per minute (unless the criteria in one of the exceptions listed in 608.1 is met).

UMC 2012 218 UMC 2015 218.0 UMC 2018 218

Topic: Definition

1. Does an air compressor meet the definition of a pressure vessel (unfired) as defined in Chapter 2 of the 2015 UMC?
2. Do the requirements of Chapter 10 of the 2015 UMC apply to air compressors?
3. Are air compressors governed by the 2015 UMC?

1. No, this definition is specific to liquids, gases, vapors and steam as applicable to a mechanical system installation.
2. No, unless by design they are incorporated into a boiler system as pertinent to Chapter 10 of the 2015 Uniform Mechanical Code.
3. No, not specifically – they might be integrated into a mechanical system or into other systems, such as medical gas, that are regulated by the Uniform Plumbing Code or NFPA 99.

UMC 2012 218.0 UMC 2015 218 UMC 2018 218

Topic: Compressed Air Systems

1. Does compressed air system piping meet the definition of "process piping" as defined in Section 218.0 of the 2015 UMC?

(1) Yes compressed air and vacuum air lines by definition of the UMC would be process piping.

UMC 2012 207.0, 217.0, 504.5 UMC 2015 207.0, 217.0, 502.2.1 UMC 2018 207.0, 217.0, 502.2.1 UMC 2021 207.0, 217.0, 502.2.1

Topic: Definition of Environmental Air Duct

1. Does the electrical room exhaust, as described in the comments, meet the definition of environmental air duct as defined in Chapter 2?
2. If so, is the termination required to comply with Section 502.2.1 for environmental air ducts?

The electrical room is provided with exhaust duct system for heat removal only. The exhaust is discharged into the adjacent area which is an occupied area.

1. No, electrical rooms are not a generally considered to be an occupied space of an occupancy as defined in the 2018 Uniform Mechanical Code section 217.0.
2. As long as the temperature of the electrical room is less than 250º Fahrenheit and is categorized as Class 1 Air under provisions of Chapter 4 Ventilation Air, the electrical room exhaust is permitted to convey to occupied areas as long as that occupied area exhaust air is terminated to the outdoors in accordance with section 502.2.1 of the 2018 UMC.