CODES

ADOPTS WITH AMENDMENTS:

International Residential Code 2015 (IRC 2015)

Part I — Administrative

Part II — Definitions

Part III — Building Planning and Construction

Part IV — Energy Conservation

Part V — Mechanical

Part VI — Fuel Gas

Part VII — Plumbing

Part VIII — Electrical

Part IX — Referenced Standards

Heads up: There are no suggested sections in this chapter.
Heads up: There are no amended sections in this chapter.

Chapter 28 Water Heaters

AMENDMENT
This section has been amended at the state or city level.
User note: Code change proposals to this chapter will be considered by the IRC — Plumbing and Mechanical Code Development Committee during the 2015 (Group A) Code Development Cycle. The text of this chapter is extracted from the 2018 edition of the North Carolina Plumbing Code and has been modified where necessary to conform to the scope of application of the North Carolina Residential Code for One- and Two-Family Dwellings. The section numbers appearing in parentheses after each section number are the section numbers of the corresponding text in the North Carolina Plumbing Code.
Hot water shall be supplied to plumbing fixtures and plumbing appliances intended for bathing, washing or culinary purposes.

P2801.2 Drain Valves

AMENDMENT
This section has been amended at the state or city level.
Drain valves for emptying shall be installed at the bottom of each tank-type water heater and hot water storage tank. Drain valves shall conform to ASSE 1005. The drain valve inlet shall be not less than 3/4-inch (19.1 mm) nominal iron pipe size and the outlet shall be provided with a male hose thread.
Water heaters shall be installed in accordance with this chapter and Chapters 20 and 24.
Water heaters and storage tanks shall be installed in accordance with Section M1305 and shall be located and connected to provide access for observation, maintenance, servicing and replacement.
Water heaters shall be located in accordance with Chapter 20.

P2801.6 Required Pan

AMENDMENT
This section has been amended at the state or city level.
Where a storage tank-type water heater or a hot water storage tank is installed in a location where water leakage from the tank will cause damage, the tank shall be installed in a pan constructed of one of the following:
  1. Galvanized steel or aluminum of not less than 0.0236 inch (0.6010 mm) in thickness.
  2. Plastic not less than 0.036 inch (0.9 mm) in thickness.
  3. Other approved materials.


A plastic pan shall not be installed beneath a gas-fired water heater.
Where a storage tank-type water heater or a hot water storage tank is installed in: (a) remote locations such as a suspended ceiling, (b) attics, (c) above occupied spaces, (d) unventilated crawl spaces, or (e) a location where water leakage from the tank will cause damage to primary structural members, the tank or water heater shall be installed in a galvanized steel or aluminum pan having a material thickness of not less than 0.0236 inch (0.6010 mm) (No. 24 gage for steel or No. 26 gage for aluminum), or other pans approved for such use.
Exceptions:
  1. Electric water heaters may rest in a high-impact plastic pan of at least 1/16 inch (1.6 mm) thickness.
  2. Water heater mounted on concrete floor with a floor drain.

P2801.6.1 Pan Size and Drain

AMENDMENT
This section has been amended at the state or city level.
The pan shall be not less than 11/2 inches (38 mm) deep and shall be of sufficient size and shape to receive dripping or condensate from the tank or water heater. The pan shall be drained by an indirect waste pipe of not less than 3/41 inch (1925.4 mm) diameter. Piping for safety pan drains shall be of those materials indicated in Table P2906.5. Where a pan drain was not previously installed, a pan drain shall not be required for a replacement water heater installation.
The pan drain shall extend full-size and terminate over a suitably located indirect waste receptor or shall extend to the exterior of the building and terminate not less than 6 inches (152 mm) and not more than 24 inches (610 mm) above the adjacent ground surface.

P2801.7 (502.5) Water Heaters Installed in Garages

AMENDMENT
This section has been amended at the state or city level.
Water heaters having an ignition source shall be elevated such that the source of ignition is not less than 18 inches (457 mm) above the garage floor. Appliances shall be located or protected so that they are not subject to physical damage by a moving vehicle. The ignition source would apply to both electric and gas water heaters. The ignition source (not the bottom of the water heater) shall be elevated to minimum of 18 inches (457 mm) above the garage floor.

Exception: Elevation of the ignition source is not required for appliances that are listed as flammable vapor ignition-resistant.
In Seismic Design Categories D0, D1 and D2 and townhouses in Seismic Design Category C, water heaters shall be anchored or strapped in the upper one-third and in the lower one-third of the appliance to resist a horizontal force equal to one-third of the operating weight of the water heater, acting in any horizontal direction, or in accordance with the appliance manufacturer's recommendations.

P2801.9 (502.2) Rooms Used as a Plenum

AMENDMENT
This section has been amended at the state or city level.
Water heaters using solid, liquid or gas fuel shall not be installed in a room containing air-handling machinery where such room is used as a plenum.

P2801.10 (502.3) Water Heaters Installed in Attics

AMENDMENT
This section has been amended at the state or city level.
Attics containing a water heater shall be provided with an opening and unobstructed passageway large enough to allow removal of the water heater. The passageway shall be not less than 30 inches (762 mm) in height and 22 inches (559 mm) in width and not more than 20 feet (6096 mm) in length when measured along the centerline of the passageway from the opening to the water heater. If 6 feet (1829 mm) of headroom is provided along the centerline of the passageway from the opening to the water heater, the length of the passageway is permitted to exceed 20 feet (6096 mm) in length. The passageway shall have continuous solid flooring not less than 24 inches (610 mm) in width. A level service space not less than 30 inches (762 mm) in length and 30 inches (762 mm) in width shall be present at the front or service side of the water heater. The clear access opening dimensions shall be not less than 20 inches by 30 inches (508 mm by 762 mm) where such dimensions are large enough to allow removal of the water heater.

P2801.11 (502.6) Installation in Crawl Spaces

AMENDMENT
This section has been amended at the state or city level.
Under-floor spaces containing appliances requiring access shall be provided with an access opening and unobstructed passageway large enough to remove the largest component of the appliance. The passageway shall not be less than 22 inches (559 mm) high and 36 inches (914 mm) wide, nor more than 20 feet (6096 mm) in length when measured along the centerline of the passageway from the opening to the equipment. A level service space not less than 30 inches (762 mm) deep and 30 inches (762 mm) wide shall be present at the front or service side of the appliance. If the depth of the passageway or the service space exceeds 12 inches (305mm) below the adjoining grade, the walls of the passageway shall be lined with concrete or masonry extending 4 inches (102 mm) above the adjoining grade and having sufficient lateral-bearing capacity to resist collapse. The clear access opening dimensions shall be a minimum of 22 inches by 30 inches (559 mm by 762 mm), where such dimensions are large enough to allow removal of the largest component of the appliance.

Exceptions:
  1. The passageway is not required where the level service space is present when the access is open and the appliance is capable of being serviced and removed through the required opening.
  2. Where the passageway is not less than 6 feet high (1829 mm) for its entire length, the passageway shall not be limited in length.

P2801.12 (502.7) Under-Floor and Exterior-Grade Installation

AMENDMENT
This section has been amended at the state or city level.

P2801.12.1 (502.7.1) Exterior-Grade Installations

AMENDMENT
This section has been amended at the state or city level.
Equipment and appliances installed above grade level shall be supported on a solid base or approved material a minimum of 2 inches (51 mm) thick.

P2801.12.2 (502.7.2) Under-Floor Installation

AMENDMENT
This section has been amended at the state or city level.
Suspended equipment shall be a minimum of 6 inches (152 mm) above the adjoining grade.

P2801.12.3 (502.7.3) Crawl Space Supports

AMENDMENT
This section has been amended at the state or city level.
The support shall be a minimum of a 2-inch (51 mm) thick solid base, 2-inch (51 mm) thick formed concrete, or stacked masonry units held in place by mortar or other approved method. The water heater shall be supported not less than 2 inches (51 mm) above grade.

P2801.12.4 (502.7.4) Drainage

AMENDMENT
This section has been amended at the state or city level.
Below-grade installations shall be provided with a natural drain or an automatic lift or sump pump. Existing installation that can be terminated outdoors must terminate outdoors. Where the installation is such that outdoor termination is impossible, indoor termination is allowable.

P2801.13 (502.8) Prohibited Installations

AMENDMENT
This section has been amended at the state or city level.
Water heaters, (using solid, liquid or gas fuel) with the exception of those having direct vent systems, shall not be installed in bathrooms and bedrooms or in a closet with access only through a bedroom or bathroom. However, water heaters of the automatic storage type may be installed as replacement in a bathroom, when approved by the plumbing official, provided they are vented and supplied with adequate combustion air.

Exception: When a closet, having a weather-stripped solid door with an approved closing device, has been designed exclusively for the water heater and where all air for combustion and ventilation is supplied from outdoors.
Where heated water is discharged from a solar thermal system to a hot water distribution system, a thermostatic mixing valve complying with ASSE 1017 shall be installed to temper the water to a temperature of not greater than 140°F (60°C). Solar thermal systems supplying hot water for both space heating and domestic uses shall comply with Section P2803.2. A temperature-indicating device shall be installed to indicate the temperature of the water discharged from the outlet of the mixing valve. The thermostatic mixing valve required by this section shall not be a substitute for water temperature limiting devices required by Chapter 27 for specific fixtures.
Isolation valves in accordance with P2903.9.2 shall be provided on the cold water feed to the water heater. Isolation valves and associated piping shall be provided to bypass solar storage tanks where the system contains multiple storage tanks.
Piping and components connected to a water heater for space heating applications shall be suitable for use with potable water in accordance with Chapter 29. Water heaters that will be used to supply potable water shall not be connected to a heating system or components previously used with nonpotable-water heating appliances. Chemicals for boiler treatment shall not be introduced into the water heater.
Where a combination water heater-space heating system requires water for space heating at temperatures exceeding 140°F (60°C), a master thermostatic mixing valve complying with ASSE 1017 shall be installed to temper the water to a temperature of not greater than 140°F (60°C) for domestic uses.
Appliances and equipment used for heating water or storing hot water shall be protected by one of the following:
  1. A separate pressure-relief valve and a separate temperature-relief valve.
  2. A combination pressure-and-temperature relief valve.
Relief valves shall have a minimum rated capacity for the equipment served and shall conform to ANSI Z21.22.
Pressure-relief valves shall have a relief rating adequate to meet the pressure conditions for the appliances or equipment protected. In tanks, they shall be installed directly into a tank tapping or in a water line close to the tank. They shall be set to open at not less than 25 psi (172 kPa) above the system pressure and not greater than 150 psi (1034 kPa). The relief-valve setting shall not exceed the rated working pressure of the tank.
Temperature-relief valves shall have a relief rating compatible with the temperature conditions of the appliances or equipment protected. The valves shall be installed such that the temperature-sensing element monitors the water within the top 6 inches (152 mm) of the tank. The valve shall be set to open at a temperature of not greater than 210°F (99°C).
Combination pressure and temperature-relief valves shall comply with the requirements for separate pressure- and temperature-relief valves.
A check or shutoff valve shall not be installed in any of the following locations:
  1. Between a relief valve and the termination point of the relief valve discharge pipe.
  2. Between a relief valve and a tank.
  3. Between a relief valve and heating appliances or equipment.

P2804.6.1 Requirements for Discharge Pipe

AMENDMENT
This section has been amended at the state or city level.
The discharge piping serving a pressure-relief valve, temperature-relief valve or combination valve shall:
  1. Not be directly connected to the drainage system.
  2. Discharge through an air gap located in the same room as the water heater either on the floor, into an indirect waste receptor or into a water heater pan.
    1. Discharge through an air gap or air gap fitting to a remote termination point that is observable by the building occupants.
  3. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap.
  4. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
  5. Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.
  6. Discharge in a manner that does not cause personal injury or structural damage.
  7. Discharge to a termination point that is readily observable by the building occupants.

    87. Not be trapped.
98. Be installed to flow by gravity.

109. Terminate not more than 6 inches (152 mm) and not less than two times the discharge pipe diameter above the floor or waste receptor flood level rim.

1110. Not have a threaded connection at the end of the piping.

1211. Not have valves or tee fittings.

1312. Be constructed of those materials indicated in Section P2906.5 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.

14. Be one nominal size larger than the size of the relief-valve outlet, where the relief-valve discharge piping is constructed of PEX or PE-RT tubing. The outlet end of such tubing shall be fastened in place. 13. The discharge pipe shall be clamped or otherwise supported with not less than one clamp or support within 12 inches (305 mm) of the point of discharge.
Bottom fed tank-type water heaters and bottom fed tanks connected to water heaters shall have a vacuum-relief valve installed that complies with ANSI Z21.22.

P2804.8 (501.9) Safety Features of Hot Water Heaters

AMENDMENT
This section has been amended at the state or city level.
The following is a reprint of N.C.G.S. 66-27.1, "Certain automatic hot water tanks or heaters to have approved relief valves; installation or sale of unapproved relief valves forbidden."
  1. No individual, firm, corporation or business shall install, sell or offer for sale any automatic hot water tank or heater of 120-gallon (454 L) capacity or less, except for a tankless water heater, which does not have installed thereon by the manufacturer of the tank or heater an American Society of Mechanical Engineers and National Board of Boiler and Pressure Vessel Inspectors approved type pressure-temperature relief valve set at or below the safe working pressure of the tank as indicated, and so labeled by the manufacturer's Identification stamped or cast upon the tank or heater or upon a plate secured to it.
  2. No individual, firm, corporation or business shall install, sell or offer for sale any relief valve, whether it be pressure type, temperature type or pressure-temperature type, which does not carry the stamp of approval of the American Society of Mechanical Engineers and the National Board of Boiler and Pressure Vessel Inspectors.
The following is a reprint of N.C.G.S. 66-27.1A, "Water heater thermostat settings."
  1. The thermostat of any new residential water heater offered for sale or lease for use in a single-family or multifamily dwelling in the State shall be preset by the manufacturer or installer no higher than approximately 120°F (49°C). A water heater reservoir temperature may be set higher if it is supplying space heaters that require higher temperatures. For purposes of this section, a water heater shall mean the primary source of hot water for any single-family or multifamily residential dwelling including, but not limited to, any solar or other hot water heating systems.
  2. Nothing in this section shall prohibit the occupant of a single-family or multiunit residential dwelling with an individual water heater from resetting or having reset the thermostat on the water heater. Any such resetting shall relieve the manufacturer or installer of the water heater and, in the case of a residential dwelling that is leased or rented, also the unit's owner, from liability for damages attributed to the resetting.
  3. A warning tag or sticker shall be placed on or near the operating thermostat control of any residential water heater. This tag or sticker shall state that the thermostat settings above the preset temperature may cause severe burns. This tag or sticker may carry such other appropriate warnings as may be agreed upon by manufacturers, installers and other interested parties.

P2804.9 (501.10) Fossil Fuel Equipment Installation

AMENDMENT
This section has been amended at the state or city level.
The installation of the following equipment and systems shall comply with the North Carolina Fuel Gas Code:
  1. Fuel piping for any fossil fuel-burning equipment.
  2. Venting systems for fossil fuel-burning equipment which is part of the plumbing system.

Section P2805 (503) Connections

AMENDMENT
This section has been amended at the state or city level.

P2805.1 (503.1) Cold Water Line Valve

AMENDMENT
This section has been amended at the state or city level.
The cold water branch line from the main water supply line to each hot water storage tank or water heater shall be provided with a valve, located within 3 feet (914 mm) of the equipment and serving only the hot water storage tank or water heater. The valve shall not interfere or cause a disruption of the cold water supply to the remainder of the cold water system. The valve shall be provided with access on the same floor level as the water heater served.

P2805.2 (503.2) Water Circulation

AMENDMENT
This section has been amended at the state or city level.
The method of connecting a circulating water heater to the tank shall provide circulation of water through the water heater. The pipe or tubes required for the installation of appliances that will draw from the water heater or storage tank shall comply with the provisions of this code for material and installation. Installation shall comply with the manufacturer's instructions and the requirements of the North Carolina Energy Conservation Code.

Section P2806 (504) Safety Devices

AMENDMENT
This section has been amended at the state or city level.

P2806.1 (504.1) Antisiphon Devices

AMENDMENT
This section has been amended at the state or city level.
An approved means, such as a cold water "dip" tube with a hole at the top or a vacuum relief valve installed in the cold water supply line above the top of the heater or tank, shall be provided to prevent siphoning of any storage water heater or tank.

P2806.2 (504.3) Shutdown

AMENDMENT
This section has been amended at the state or city level.
A means for disconnecting an electric hot water supply system from its energy supply shall be provided in accordance with NFPA 70. A separate valve shall be provided to shut off the energy fuel supply to all other types of hot water supply systems.

Section P2807 (505) Insulation

AMENDMENT
This section has been amended at the state or city level.

P2807.1 (505.1) Unfired Vessel Insulation

AMENDMENT
This section has been amended at the state or city level.
Unfired hot water storage tanks shall be insulated to R-12.5 (h • ft2 • °F)/Btu (R-2.2 m2 • K/W).
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