This is a continuation of a summary of the significant code changes to the 2021 Uniform Plumbing Code (UPC) which is developed and promoted by the International Association of Plumbing and Mechanical Officials. 

These code changes will appear in the 2021 edition of the International Plumbing Code. Because it is possible for modifications to be made during the final hearing process and because there were multiple changes made to some code sections, the final edited version may be slightly different than what was in the actual code change proposal. Refer to the 2021 International Plumbing Code for the final version of any code changes. 

The proposed new code language is underlined. The text proposed to be deleted is stricken through. The proposed changes are followed by the proponent’s published reason statements, and occasionally by my comments when noted.

2021 UPC Code, General Code Correlation Items Throughout the Code

There were numerous references throughout the plumbing code that referenced Table 701.1, 1701.2 for the reference standards for a given application. One code change was to make a universal change to just refer to chapter 17 Referenced Standards, instead of referring to the table number or section number.

Proponent’s reason statement: The Technical Correlation Committee issued the following reason statement for moving the referenced standards from Table 1701.1 or Table 1701.2 to Chapter 17.  

The language for UPC is being revised to correlate with the language approved by the UMC Technical Committee regarding allowing the end user to use an applicable approved standard in Table 1701.2. Furthermore, the language in the UPC is being revised from “Table 1701.1” to “Chapter 17” as an appropriate standard may be located in either Table 1701.1 or Table 1701.2.

The reason provided by the UMC Technical Committee for their acceptance is as follows: The sections being revised contradict other sections. Furthermore, the revision allows the end user to use an applicable approved standard in Table 1701.2. The proposed modification will prevent confusion in the field and will prevent contradictions within the UMC. These sections must be revised as the approved standards in Table 1701.2 can be used, where applicable, without additional approval in accordance with Section 302.2.

The action moves forward as approved by the Technical Correlation Committee and supersedes the recommendation from the UPC Technical Committee for actions taken for Section 301.2.2 through Section 402.6.1 in regards to allowing the end user to use an applicable approved standard in 1701.2.

 My comments: This was simply changing a bunch of references to standards listed in two tables in chapter 17 to simply saying refer to chapter 17. 

2021 UPC Code, Chapter 6, Section 603.2, Table 1701.1, 1701.2 

Revise the text sections and tables as follows (the remaining text is unchanged):

603.0 Cross-Connection Control. 

603.3 Backflow Prevention Devices, Assemblies, and Methods. Backflow prevention devices, assemblies, and methods shall comply with Section 603.3.1 through Section 603.3.9 603.3.12. 

603.3.10 Dual Check Backflow Preventer. A dual check backflow preventer consists of two independently acting check valves, force loaded to a normally closed position.

603.5.15.1 603.3.11 Laboratory Faucet Backflow Preventers. Laboratory faucets shall be protected by a backflow preventers that shall complies comply with ASSE 1035.

603.3.12 Backflow Preventer with Intermediate Atmospheric Vent. 

A backflow preventer with intermediate atmospheric vent consists of two independently acting check valves, force loaded to a normally closed position, and an intermediate chamber with a means for automatically venting to atmosphere, force loaded to a normally open position.

603.5 Specific Requirements. 

603.5.10 Steam or Hot Water Boilers. Potable water connections to steam or hot water boilers shall be protected from backflow by a double check valve backflow prevention assembly, backflow preventer with intermediate atmospheric vent and pressure reducing valve, or reduced pressure principle backflow prevention assembly in accordance with Table 603.2. Where chemicals are introduced into the system a reduced pressure principle backflow prevention assembly shall be provided in accordance with Table 603.2.

TABLE 603.2

BACKFLOW PREVENTION DEVICES, ASSEMBLIES, AND METHODS

(Portions of table not shown don’t change.)

TABLE 1701.1

REFERENCED STANDARDS

(Portions of table not shown don’t change.)

TABLE 1701.2

STANDARDS, PUBLICATIONS, PRACTICES, AND GUIDES

(Portions of table not shown don’t change.)

Proponent’s reason statements: 

ASSE 1012: Backflow preventers with intermediate atmospheric vents are generally accepted means of backflow protection in low-hazard backpressure and back-siphonage situations. Per the IAPMO and UA Backflow Prevention Reference Manual 3rd Edition, the devices are installed for residential, low-pressure boilers. ASSE 1012 devices have functional capabilities for preventing both back-siphonage and backpressure, and may operate under continuous or intermittent pressure conditions. 

These devices have two independently operating check valves separated by an intermediate chamber with a means for automatically venting it to the atmosphere and can be installed in the horizontal, vertical up or vertical down orientations. The check valves are force-loaded to a normally closed position and the venting means is force loaded to a normally open position. 

 The description of the device is in line with the other sections of Section 603.3. One such section is included (603.3.7) as an example. Also, Table 603.2 has been updated with the appropriate installation exclusion. These devices are used for low-hazard isolation backflow protection in locations such as boiler feeds that do not use chemicals.

ASSE 1024: The description of the ASSE 1024 device is in line with the other sections of Section 603.3, including one such section (603.3.7) as an example. Also, the table has been updated with the appropriate installation exclusion. 

These devices are used for low-hazard isolation backflow protection for appliances such as coffee machines and other noncarbonated drink dispensers. 

ASSE 1035: Given the use of laboratory faucets, they are subject to high-hazard situations and may be used to connect a hose. These devices are able to protect against back-siphonage and backpressure, and are not for continuous pressure. ASSE 1035 applies only to those devices classified as backflow preventers that are designed for installation on laboratory faucets on the discharge side of the last shut-off valve. They are not for use under constant pressure conditions. 

These devices consist of two independently acting check valves, force-loaded or biased to a normally closed position, and between the check valves a means for automatically venting to atmosphere, force loaded or biased to normally open position.

The intent of this committee proposal on ASSE 1035 was to add direct reference to ASSE 1035 in the body of the code such that the standard becomes mandatory in Chapter 17 or Table 1701.1. The correct location for referencing backflow preventer standards is Section 603.3. Hence, the change is to move the text to Section 603.3.11 (the next new section). 

Additionally, the text should only reference the backflow preventer, not the application. This is similar to the text that appears in Section 603.3. There are multiple options for backflow prevention for faucets used in laboratories. However, the specific backflow preventer is identified as a "Laboratory Faucet Backflow Preventer." Thus, the section should only reference the name of the product and the applicable standard.

ASSE 1081: ASSE 1081 covers devices that have combined two products, one compliant to ASSE 1003 and the other to ASSE 1012. These devices have different hydrodynamic needs, hence the new standard for the complete device. It is comprised of a pressure-reducing valve, two force-closed checks in series, and a forced-open intermediate vent between the checks. 

ASSE 1081 devices are installed in plumbing systems to fill and reduce static boiler pressure under normal conditions, as well as to prevent backflow into potable water supply lines within a premise when pressure is temporarily higher in the closed boiler loop than in the potable water piping. Since the valves are boiler feed valves, they are not installed directly into the potable water pipeline and are not intended for use as potable water products. 

This device is for a low-hazard installation where high-hazard chemicals are not used in the hot water system. Also, this device is designed specifically for boiler feed lines. Proposal text has been corrected as such. 

These products protect the potable water supply from low-hazard backflow from boiler feed lines. They also ensure that the heating hot water recirculation system has the appropriate minimum pressure by way of the integral pressure reducing device, when the supply pressure is higher than the recirculation system pressure.

2021 UPC Code, Chapter 6, Table 604.1

Revise table as follows:

TABLE 604.1

MATERIALS FOR BUILDING SUPPLY AND WATER DISTRIBUTION PIPING AND FITTINGS

(Portions of table not shown don’t change.)

Proponent’s reason statement: ASTM F877 is not a pipe standard. As of the 2011 edition of the standard, ASTM F877 no longer applied to “tubing” for classification or testing. For your information, the classification section of the 2011 edition of the standard now reads as follows: 

5. Classification

5.1 Fittings—This specification classifies fittings, including manifolds, intended for use in systems with PEX tubing by a maximum continuous use temperature that shall be 180° F (82° C) and by nominal sizes from 1/8 inch through 6 inches on the basis of resistance to burst pressure, hydrostatic sustained pressure, excessive temperature pressure capability, and by thermocycling. Fittings shall be compatible with tubing made to the requirements of Specification F876.

This is a case where a standard that was once applicable has gone through a drastic change, and is no longer appropriate as a pipe standard.

2021 UPC Code, Chapter 6, Table 604.1 and Table 1701.1 

Revise table as follows:

TABLE 604.1

MATERIALS FOR BUILDING SUPPLY AND WATER DISTRIBUTION PIPING AND FITTINGS

(Portions of table not shown don’t change.)

TABLE 1701.1

REFERENCED STANDARDS

Proponent’s reason statement: The proposed modification removes reference to ASTM F1961 and ASTM F2262 as the promulgator has withdrawn the standards.

2021 UPC Code, Chapter 6, Section 606.8

Add new text as follows:

606.0 Valves. 

606.8 Check Valve Required. All systems that circulate water by means of a pump or other mechanical device or method shall have a check valve(s) or equal device(s) installed so as to insure the direction of flow.

Proponent’s reason statement: Many water heaters have circulation pumps installed. There is no requirement to have a check valve or other method to ensure the proper direction of flow. This issue will only get worse as more circulation pumps are installed as a result of green water-saving efforts. The language also allows more than one check valve or device.

My comments: Many installations with a small circulator and no check valve experience reversal of flow because the domestic hot water circulating pump is typically located in the coolest portion of the circulated hot water piping, which would be on the hot water return piping just before it connects to the cold water supply inlet to the water heater. 

In large buildings where there is no check valve after the circulating pump, hot water branches near the hot water circulating pump often experience a reversal of flow through the circulating pump. The path of least resistance can be back through the circulating pump and to the nearby hot water branch that is flowing rather than through the long hot piping water route that includes the water heater(s) mixing valves, and the hot water distribution piping before returning toward the water heater through the hot water return pipe and circulating pump. 

When no check valve is on the discharge of the pump, cold water can follow the path of least resistance and flow from the hot water faucets of branches near the end of the circulated hot water loop. Many hot water circulating pumps are fractional horsepower, making it easy for water to flow backwards through the circulating pump. This is cured by installing a check valve on the discharge of the circulating pump, ensuring the cold water will not flow backwards through the hot water return pipe to nearby fixtures. 

Although not required by this code change, it would be a good idea to install a temperature gauge on the discharge of the circulating pump to be able to see the hot water return temperature. The hot water return temperature should be kept a couple of degrees above the Legionella bacteria growth temperature of 122 F. This causes the entire hot water distribution system to be above 120 F, so all bathtub-shower valve maximum temperature-limit stops should be adjusted to a code-compliant and safe temperature below 120 F. 

I like to install a temperature-actuated mixing valve on the water heater and adjust it so that during off-peak hours, the hot water return temperature just downstream of the hot water circulating pump is around 124 F — a temperature that will not promote bacterial growth. Then the bathtub-shower maximum temperature rotational limit-stops can be adjusted and thermostatic temperature-limiting valves can be installed on bathtubs, whirlpool bathtubs and other fixtures requiring a safe temperature for washing or personal hygiene.

Also, I like to set the maximum temperature limit stop on bathtub-shower valves around 110 F to 112 F or as required to provide an additional level of scald prevention. According to burn research on scald burns by doctors at Harvard Medical College, adult males can receive a second-degree blistering burn in 4.8 minutes at 120 F. Women, children, the elderly will have skin thinner than an adult male and can burn even quicker. 

A paper published and presented at the American Society of Sanitary Engineering and the American Society of Plumbing Engineers conferences in the late 1990s by Dr. D. Bynum, shows children can receive second-degree blistering burns in 1.2 minutes at 120 F. At 110 F, it would take 2.5 hours for a child to receive a second-degree blistering burn based on a ratio of skin thickness from an adult to a child. For this reason, it is much safer to set the limit stops as low as possible to still get a comfortable shower around 110 F. 

The thermostat on the water heater should never be used to adjust the final temperature at the fixtures. The codes previously prohibited this practice for purposes of scald protection. This was for many reasons, including the thermostat on a storage-type water heater can allow the temperature to rise 20 to 30 degrees above the set-point under certain usage conditions. 

The language prohibiting the water heater thermostat from being the final temperature to prevent scalding at fixtures was eliminated when code change proposals came out for the ASSE 1084 standard for point-of-use water heaters that limit hot water temperatures. The language prohibiting the thermostat on water heaters from controlling the temperature at fixtures should be reinstated along with an exception for water heaters conforming to ASSE 1084 or 1085 when they are installed at the point-of-use. 

However, water heaters that conform to ASSE 1082, which are source water heaters, were included in those code change proposals. If there is a large temperature drop across the hot water system, accurate control of the temperature at all points of use simultaneously is not possible with an ASSE 1082 temperature-limiting water heater. 

I have seen buildings with as much as a 40-degree temperature drop from the hot water leaving the water heater and the hot water return temperature. The temperature at the farthest fixture will be about 20 degrees cooler than the temperature leaving the water heater. Although this is not the best of designs, it is a reality. 

The temperature at fixtures near the water heater may only be a degree or two below the temperature of the water leaving the unit. There can be close to a 20-degree difference in the hot water temperature at two different fixtures supplied by the same master mixing valve or an ASSE 1082 temperature-limiting-type water heater designed for source water temperature control. 

So, it is virtually impossible to deliver the same temperature to all fixtures relying only on the water heater thermostat or a master thermostatic mixing valve. This is why hot water temperatures should be kept higher to allow for more hot water to be stored for use during peak demand periods; you get the benefit of pasteurization of the hot water system. The limit stops at the bathtub-shower fixtures should be adjusted and point-of-use tempering devices should be used and adjusted to a safe temperature. 

Note: If the hot water distribution system temperature is ever changed in any way — such as a new water heater, adjusting the thermostat dial to a different temperature on the water heater or adjusting the set-point on the temperature-actuated mixing valve — then every shower valve and temperature-limiting valve in the building must be checked and readjusted to ensure the hot water temperature is safe. 

This is a continuing series covering significant code changes from the 2018 to the 2021 edition of the Uniform Plumbing Code. It will continue next month.