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 7

9 results

UMC 2003 701.1 (D), see also 1107.6 UMC 2006 701.1.4, see also 1107.6 UMC 2009 701.1.4, see also 1107.6 UMC 2012 701.3, see also 1107.6

Topic: Prohibited Source for Combustion Air

The provision in Section 703.3 of 2000 UMC is not available in the 2006 UMC. Has this requirement been deleted without replacement or relocated? If it has been relocated, could you please tell where I can find it in 2006 UMC?

Most of Chapter 7 of the 2000 UMC has been replaced by extracted language from NFPA 54. The requirements specified in Section 703.3 of the 2000 UMC can now be found in Sections 701.1.4 and 1107.6 of the 2006 UMC. Although the exact language has changed, the purpose of the code to provide minimum standards to safeguard the public welfare has not changed.

UMC 2003 701.1.1 UMC 2006 701.1.1 UMC 2009 701.1.1 UMC 2012 701.1.1

Topic: Combustion Air Evaluations

These questions are related to Section 701.1.1 in regards to combustion air evaluations in existing homes (i.e., built 5 to 50 years ago).

1. When calculating indoor volume for combustion air in a residence, are the Btu/h input ratings of cooking appliances and clothes dryers excluded the way they were in the 2000 UMC?

2. When calculating room volume for a natural draft wall furnace in the living room, must the Btu/h input of the pre-existing gas range in the kitchen (manufacturer's instructions not known) be added to that of the wall furnace?

1. No. Section 701.1.1 provides exceptions for direct vent appliances and Type I clothes dryers that are provided with makeup air in accordance with Section 504.3.2. Gas appliances other than natural draft design and other than Category 1 appliances shall be provided with combustion, ventilation and dilution air in accordance with the appliance manufacturer’s instructions. If the cooking appliance is a natural draft type, the total Btu/h input shall be included when calculating the indoor room volume.

2. Yes, if the two rooms freely communicate without doors.

UMC 2003 701.2 UMC 2006 701.2 UMC 2009 701.2 UMC 2012 701.4

Topic: Combustion Air Calculations

Does the height restriction of 8 feet in Section 304.2 (303.2, 2009) also apply to Section 701.2, which requires the volume of the room or space to be equal to or greater than 50 cubic feet per 1,000 Btu/h?

No. This calculation is used only for calculating the minimum volume of rooms containing fuel-burning equipment not listed for closet or alcove installation. Note: The reference to the 8 foot ceiling in the training manual is only a coincidental example, as most ceilings are approximately 8 feet in height.

UMC 2003 701.4, see also 1021.0 UMC 2006 701.4, see also 1020.0 UMC 2009 701.4, see also 1019.0 UMC 2012 701.4, see also 1019.0

Topic: Combustion Air Requirements

Is it possible that the requirements for combustion air into a boiler room be different for a forced draft boiler/burner that pulls in combustion air to the burner via its own motor and fan versus that of a natural draft-type burner that does not?

Yes. Sections 1021.0 (2003), 1020.0 (2006) and 1019.0 (2009/2012) refers you to Chapter 7 for combustion air requirements. Section 701.1.1 states “Gas utilization equipment of other than natural draft and Category I vented appliances shall be provided with combustion, ventilation, and dilution air in accordance with the equipment manufacturer’s instructions.” If the manufacturer’s instructions do not address combustion air, than the provisions of Sections 701.6 or 701.7 (2003/2006/2009/2012) must be followed.

UMC 2003 704.1 UMC 2006 704.1 UMC 2009 704.1 UMC 2012 701.6.1

Topic: Combustion Air

When using the 2 opening method, does the code require that the entire combustion air opening be located within 12 inches of the floor and within 12 inches of the ceiling of the heater enclosure or does the code permit that a portion of the combustion air opening be located, that is, start within 12 inches of the floor or ceiling with the balance of the opening permitted to be more than 12 inches above the floor (or more than 12 inches below the ceiling)?

No. The code would permit the opening to start above or below those thresholds and not be completely within that space.

UMC 2003 701.4.2 UMC 2006 701.4.2 UMC 2009 701.4.2 UMC 2012 701.6.2

Topic: Combustion Air Ducts

If a furnace compartment does not have a ceiling and is open to a ventilated attic, do we still need to bring in lower combustion air into the furnace compartment?

Yes. The purpose of the upper and lower openings is to vent the appliance compartment. The hot air will rise and be replaced by the cooler lower combustion air opening. Furthermore, the code has a provision for the one opening method and the lower combustion opening would not be required so long as the provisions of Section 701.4.2 are met.

UMC 2003 701.1 (A) UMC 2006 701.1.1 UMC 2009 701.1.1 UMC 2012 701.1

Topic: Combustion Air

When calculating combustion air room volume in a residence, is it necessary to include the Btu/h Input ratings of gas cooking appliances (i.e., all cooktop burner plus the oven burner)?

Yes, the exceptions only apply to direct vent appliances and clothes dryer installations in conformance to the requirements of Chapter 9 of the Uniform Mechanical Code.

UMC 2006 701.1.1; 902.0 (B) UMC 2009 701.1.1; 902.0 (B) UMC 2012 701.0, 902.2 UMC 2015 701.0; 902.2

Topic: Combustion Air

Section 701.1 (A) (2003); 701.1.1 (2006/2009); 701.0 (2012/2015) and 902.0 (B) (2003/2006/2009); 902.2 (2012/2015) state that gas appliances that take combustion air cannot be located in bathrooms, does this prohibit the installation of a gas dryer in a bathroom that is provided with the required make-up air, is exhausted per code requirements and the bathroom is exhausted as required?

No. A Type I clothes gas dryer can be installed in a bathroom with only providing for make-up air when installed in accordance with Section 905.3 (2003/2006/2009/2012); 504.4.1 (2015). Section 701.1 exception # 2 states that Type 1 clothes dryer don’t have to meet combustion air requirements, just provide make-up air. This exception only applies to Type 1 clothes dryers; other types of appliances do need to comply with the UMC requirements for combustion, ventilation and dilution air.

UMC 2009 701.1(2), (3) UMC 2012 701.11(2), (3) UMC 2015 701.11(2), (3) UMC 2018 701.11(2), (3)

Topic: Combustion Air Ducts

Is there any language in the mechanical code that would restrict or prohibit supplying combustion air from a ventilated attached garage ceiling to a remote mechanical room elsewhere in the house?

You cannot bring combustion air from a garage. Combustion air shall not be obtained from a hazardous location or from any area in which objectionable quantities of flammable vapor are released. Combustion Air ducts would be limited to approved materials for their intended use.