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.

Click to search by UPC Table Of Contents Click to search by UMC Table Of Contents

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

Keywords

Code

Code Year

Section

Match EXACT search terms

Match ALL search terms

Match ANY search terms

Questions matching UMC Chapter 12

9 results

UMC 2003 1201.2.1.4.2.1 UMC 2006 1201.2.1.4.2.1 UMC 2009 1201.2.1.4.2.1 UMC 2012 1201.3.2.5

Topic: Joints and Connections

We are doing a hydronics job in a high-rise building and would like to use a tee-puller to create fittings and then braze the joints. Is this allowed in the mechanical code?

Yes. These type of joints would be acceptable according to Section 1201.2.1.4.2.1 (1201.3.2.5/2012) when used according to their listing and applicable installation instructions.

UMC 2003 1201.2.6.2.1 UMC 2006 1201.2.6.2.1 UMC 2009 1201.2.6.2.1 UMC 2012 1201.3.7, see also 316.3

Topic: Horizontal Piping Support

Is the piping required to be secured (strapped) to the supports to maintain alignment?

Yes. Strapping or securing the pipe to the support is necessary to maintain alignment as required by the code.

UMC 2003 1201.2.7.1 UMC 2006 1201.2.7.1 UMC 2009 1201.2.7.1 UMC 2012 1201.3.8

Topic: Dissimilar Materials

There is no mention of the mixing of dissimilar metals. Even though a heating or cooling system is a closed system, are dielectric insulators required?

No. Section 1201.2.7.1 (1201.3.8/2012) states, “All piping materials used, except valves and similar devices, shall be of a like material, except as otherwise acceptable to the Authority Having Jurisdiction.” The UMC does not specifically require that dielectric or insulating unions be installed in a hydronic system; however, if dissimilar materials are used, the potential exists for premature failure by galvanic action due to electrolysis.

It is the responsibility of the Authority Having Jurisdiction to evaluate each installation as to the use of dissimilar materials and to determine the method or methods to be employed to protect the system. Chapter 12 (2003/2006/2009/2012) does address other types of corrosion and erosion in the installation of a hydronics heating system.

UMC 2003 1201.2.7.7 UMC 2006 1201.2.7.7 UMC 2009 1201.2.7.7 UMC 2012 1201.3.8.5(A)

Topic: Underground Piping

Can 12" PVC bell and spigot pipe with rubber ring gaskets and fittings be installed underground beneath a chiller building on chilled water piping mains?

No. All piping systems in which the pressure does not exceed 160 psig and the temperature does not exceed 250°F shall comply with the provisions of UMC Section 1201.2 (1201.3/2012). Section 1201.2.1.1 (2003/2006/2009) (1201.3.2/2012) states that all pipe shall be brass, copper, cast iron, galvanized or black wrought iron, galvanized or black steel, or other approved materials. In addition, Section 1201.2.1.13 (2003/2006/2009) (1201.3.2.16/2012) indicates all piping, tubing, valves, joints, fittings, devices and materials shall be free of defects and comply with nationally recognized standards approved by the Administrative Authority. Section 1201.2.7.7 (2003/2006/2009) (1201.3.8.5(A)/2012) only allows ferrous and copper piping beneath buildings.

It is possible the Administrative Authority may approve the material if it meets the provisions of Section 1201.2.1.15 (2003) which requires the material to be equivalent for the use intended to those specified in Chapter 12 (2003/2006/2009).

UMC 2003 1201.2.7.7.5 UMC 2006 1201.2.7.7.5 UMC 2009 1201.2.7.7.5 UMC 2012 1201.3.8.5(C)

Topic: Sealing of Voids Around Pipes

Is it required that voids around piping passing through concrete floors on the ground be appropriately sealed? For example, in houses with slab-on-grade construction, where the drain line for the tub and shower penetrates the slab, is this area required to be sealed?

Yes. All pipe openings in an on-grade slab within the fixed limits of the building foundation must be "appropriately sealed" to prevent insects or vermin from entering the building.

UMC 2009 1201.2.7.1 UMC 2012 1201.3.8

Topic: Dissimilar materials

I am seeking your technical feedback regarding the connection between dissimilar materials (drain valve brass and carbon steel pipe) with threaded joint connection being utilized in HVAC chilled system. I know this connection requires dielelectric insulating unions between the dissimilar metal connection to avoid the bimetallic corrosion. The sizes of this materials are less than 2 inches.

We have a project where hundreds of these connections have been installed without the insulating unions. How long until the corrosion will accrue without the insulating union? Is it acceptable or I should installed the dielectric insulating union.

No. This specific requirement not addressed in the Uniform Mechanical Code. Section 1201.2.7.1 (2009); 1201.3.8 (2012) only requires that all materials used shall be of like materials with the exception of valves and similar devices therefore an dielectric insulation union is not required at the connection.

It is unknown if corrosion will accrue without the use of dielectric insulating unions as the accumulation of corrosion is a function of the hydronic fluid acting as an electrolyte in the process of ionic transfer.

UMC 2015 1205.2, 1210.1 UMC 2018 1205.2, 1210.1

Topic: Pressure Testing Pipe, Tubing, and Fittings

1. Do the hoses and the hose clamps need to be UL listed or otherwise tested by a recognized agency to confirm suitability? 2. Table 1210.1 does not appear to address hoses and clamps. Is that correct?
3. Is this addressed elsewhere in the code?

1. No, Table 1210.1 of the 2015 Uniform Mechanical Code covers most applications but does not list rubber hose and clamps. Rubber hoses are not an approved material to be used for Hydronic systems. The approved materials for hydronic system piping are listed in Table 1210.1. Rubber hoses and clamps are not listed in that table.
2. Yes, see Answer 1
3. Yes, section 302.0 Materials-standards and alternatives.

UMC 2018 1209.4

Topic: Closed Type Tanks

Do closed-type expansion tanks need to be field tested at 2.5 times the allowable working pressure of the hydronic system?

No, Section 1209.4 of the 2018 Uniform Mechanical Code states that the closed-type expansion tanks shall be designed for hydrostatic test pressure of 2.5 times the allowable working pressure of the system, not field tested at this pressure. In addition, this section also requires any system designed to operate at more than 30 psi have its tank comply with ASME BPVC Section VIII requirements.

UMC 2018 1210.2

Topic: Expansion and contraction

Does section 1210.2 Expansion and contraction under the hydronics chapter apply to VAV boxes and heating coils?

The piping portion would have to comply with Section 1210.2 of the 2018 Uniform Mechanical Code, which applies only to pipe and tubing installed by the contractor. This section of the UMC would not necessarily pertain to the VAV box and heating coils directly, but it does for any of the piping going to the coil. That piping would need to installed to accommodate any expansion and contraction. The components of a VAV Box and its coils would be governed by its listing, as applicable to the actual VAV box or coils and associated piping within the VAV. However, per this section piping and tubing connecting to the VAV boxes shall comply with this section.