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D.C. Municipal Regulations (Last Updated: September 13, 2017) |
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Title 12. CONSTRUCTION CODES SUPPLEMENT OF 2013 |
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SubTilte 12-E. MECHANICAL CODE SUPPLEMENT OF 2013 |
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Chapter 12-E10. BOILERS, WATER HEATERS AND PRESSURE VESSELS |
Section 12-E1015. WATER STORAGE TANKS, WATER HEATERS, HYDRO-PNEUMATIC TANKS
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Insert new Section 1015 in the Mechanical Code to read as follows:
1015.1 Limited capacity storage tanks. Each hot water storage tank, range boiler, or automatic storage water heater, having a nominal water-containing capacity of 120 gallons (454 L) or less shall be built for a minimum working pressure of 125 pounds per square inch (psi) (862 kPa) and shall be tested hydrostatically to 300 pounds per square inch (psi) (2069 kPa). Each tank shall have clearly and indelibly stamped or stenciled thereon the name of the manufacturer, the maximum allowable working pressure for which it is built, and the test pressure.
1015.2 Tank labeling. Each hot water tank shall be stamped with the ASME symbol to indicate that it is constructed in accordance with the ASME Code. It shall also be stamped with the name of the manufacturer, the maximum allowable working pressure, the year built and the identifying number of the National Board.
1015.3 Manufacturer’s data report. Applications for permits for hot water storage tanks as described in Section 1015.1 shall be accompanied by the manufacturer’s data report, which shall be signed by an inspector licensed by the National Board to inspect boilers and pressure vessels.
1015.4 Gas-fired automatic storage water heaters. Gas-fired automatic storage water heaters shall bear a label indicating approval and listing in accordance with the Fuel Gas Code.
1015.5 Oil-fired or electrically-heated water heaters. Oil-fired or electrically-heated automatic storage water heaters shall be listed and labeled, and shall bear the label of an approved listing agency.
1015.6 Storage water heater label. Each storage water heater shall bear the manufacturer’s trade name or trademark, the catalog number, the input rating in Btu/h (W), the output in gallons per hour at 100 °F rise in temperature, and the nominal capacity of the storage tank, in gallons (L).
1015.7 Storage tank installation. Storage tanks shall be substantially supported by one of the following methods:
1. Installed on steel supports constructed of pipe or structural steel and resting upon a structurally sound floor;
2.Hung from supports attached to structural steel or concrete beams that have been determined to be of sufficient strength to support the additional weight; or
3.Installed upon concrete saddles.
In all cases, provision shall be made to take care of expansion. Tanks shall not be supported by their piping system. Manhole openings shall be kept clear of all walls, pipes or other obstructions.
1015.8Gas-fired water heater venting. Each gas-fired water heater shall be provided with an approved draft diverter installed in accordance with the manufacturer’s installation instructions and connected to an effective chimney. Connection to a common chimney shall be made above the entrance of other larger vent connectors or breechings, in accordance with Section 803.7.
1015.9Commercial and industrial installations. In commercial and industrial establishments, when a connection to a chimney is impracticable, the installation of an automatic unvented water heater shall be approved by the code official if all of the following requirements are met:
1.The flow of gas supply shall be limited, by fixed orifices, to the maximum flow values specified in Table 1015.9 as a function of the net interior volume of the space in which the heater is located the maximum input rating of the heater shall not exceed 10,000 BTU per hour (3 kW); and
2.The heater shall otherwise conform to the Construction Codes.
TABLE 1015.9
MAXIMUM ALLOWABLE GAS FLOW
FOR UNVENTED COMMERCIAL AND INDUSTRIAL WATER HEATERS
Net Volume of Room or Space
(cubic feet)
MAXIMUM ALLOWABLE GAS FLOW
(CUBIC FEET PER HOUR, CFH)
COLUMN NO. 1 a
COLUMN NO. 2 b
1000 to 1500
2
3
1501 to 2000
3
4
2001 to 2500
4
5
2501 to 3000
5
6
3001 to 3500
6
7
3501 to 4000
7
8
Over 4000
8
8
For SI: 1 cubic foot = 0.028 m3, 1 CFH = 0.028 m3/h
a. Column No.1 applies to appliances located in spaces that do not have openings to other spaces.
b. Column No. 2 applies to appliances located in spaces that have permanent openings of at least 15 square feet (1.4 m2) leading to another space of equal or greater volume.
1015.10 Prohibited use. Water from a hot water supply boiler, automatic water heater coil or tank shall not be used for building heating, except for auxiliary space heating, permitted to have a by-pass from any such boiler or heater, provided that there is no actual withdrawal of water from the unit and that all surfaces and connections in contact with the water are of copper or other approved corrosion resistant material.
1015.11 Existing tanks. A tank currently in use shall not be painted, lined or repaired on the inside with any material or in any manner that will affect either the color or taste of the water supply after the tank is put into service. Any material intended for use as a lining or protective coating for the interior of tanks shall be submitted to the code official for approval.
1015.12 Tank maintenance and repair. The water supply connections to and from the tank shall be disconnected or plugged while the tank is being cleaned, painted, lined or repaired, to prevent any foreign fluid or substance from entering the distribution piping. Adequate measures shall be taken for the protection of workers in the tank.
1015.13 Welding repair. Any repair by welding on a tank shall be done by a qualified welder licensed by the Department and the work shall be witnessed by the code official.
1015.14 Alterations or additions. When changes or additions are made to an existing hot water supply system or when a storage tank is replaced or moved, compliance with the provisions of this chapter shall be required.
Exception: When there is no available opening in the top of an automatic storage water heater with a nominal water containing capacity 120 gallons (454 L) or less, it shall be permissible to install the relief valve in the outlet header from the heater, with only one fitting between the relief valve and the tank.