About this chapter: Chapter 10 addresses boilers, water heaters, expansion tanks and pressure vessels in general, such as compressed air vessels. This chapter includes requirements for components of hydronic HVAC systems, with the focus being on safety, maintenance, testing and safety control devices.
This chapter shall govern the installation, alteration and repair of boilers, water heaters and pressure vessels.
- Pressure vessels used for unheated water supply.
- Portable unfired pressure vessels and Interstate Commerce Commission containers.
- Containers for bulk oxygen and medical gas.
- Unfired pressure vessels having a volume of 5 cubic feet (0.14 m3) or less operating at pressures not exceeding 250 pounds per square inch (psi) (1724 kPa) and located within occupancies of Groups B, F, H, M, R, S and U.
- Pressure vessels used in refrigeration systems that are regulated by Chapter 11 of this code.
- Pressure tanks used in conjunction with coaxial cables, telephone cables, power cables and other similar humidity control systems.
- Any boiler or pressure vessel subject to inspection by federal or state inspectors.
Potable water heaters and hot water storage tanks shall be listed and labeled and installed in accordance with the manufacturer's instructions, the International Plumbing Code and this code. Water heaters shall be capable of being removed without first removing a permanent portion of the building structure. The potable water connections and relief valves for all water heaters shall conform to the requirements of the International Plumbing Code. Domestic electric water heaters shall comply with UL 174 or UL 1453. Commercial electric water heaters shall comply with UL 1453. Oil-fired water heaters shall comply with UL 732. Solid-fuel-fired water heaters shall comply with UL 2523. Solar thermal water heating systems shall comply with Chapter 14 and ICC 900/SRCC 300.
Water heaters utilized both to supply potable hot water and provide hot water for space-heating applications shall be listed and labeled for such applications by the manufacturer and shall be installed in accordance with the manufacturer's instructions and the International Plumbing Code.
Water heaters utilized for both potable water heating and space-heating applications shall be sized to prevent the space-heating load from diminishing the required potable water-heating capacity.
Where a combination potable water-heating and space-heating system requires water for space heating at temperatures higher than 140°F (60°C), a temperature-actuated mixing valve that conforms to ASSE 1017 shall be provided to temper the water supplied to the potable hot water distribution system to a temperature of 140°F (60°C) or less.
Potable water-heating devices that utilize refrigerant-to-water heat exchangers shall be approved and installed in accordance with the International Plumbing Code and the manufacturer's instructions.
All pressure vessels, unless otherwise approved, shall be constructed and certified in accordance with the ASME Boiler and Pressure Vessel Code, and shall be installed in accordance with the manufacturer's instructions and nationally recognized standards. Directly fired pressure vessels shall meet the requirements of Section 1004.
All piping materials, fittings, joints, connections and devices associated with systems utilized in conjunction with pressure vessels shall be designed for the specific application and shall be approved.
Welding on pressure vessels shall be performed by an R-Stamp holder in accordance with the National Board Inspection Code, Part 3 or in accordance with an approved standard.
Boilers shall be designed, constructed and certified in accordance with the ASME Boiler and Pressure Vessel Code, Section I or IV. Controls and safety devices for boilers with fuel input ratings of 12,500,000 Btu/hr (3,662,500 W) or less shall meet the requirements of ASME CSD-1. Controls and safety devices for boilers with inputs greater than 12,500,000 Btu/hr (3,662,500 W) shall meet the requirements of NFPA 85. Packaged oil-fired boilers shall be listed and labeled in accordance with UL 726. Packaged electric boilers shall be listed and labeled in accordance with UL 834. Solid-fuel-fired boilers shall be listed and labeled in accordance with UL 2523.
In addition to the requirements of this code, the installation of boilers shall conform to the manufacturer's instructions. Operating instructions of a permanent type shall be attached to the boiler. Boilers shall have all controls set, adjusted and tested by the installer. The manufacturer's rating data and the nameplate shall be attached to the boiler.
Clearances shall be maintained around boilers, generators, heaters, tanks and related equipment and appliances so as to permit inspection, servicing, repair, replacement and visibility of all gauges. Where boilers are installed or replaced, clearance shall be provided to allow access for inspection, maintenance and repair. Passageways around all sides of boilers shall have an unobstructed width of not less than 18 inches (457 mm), unless otherwise approved.
Clearances from the tops of boilers to the ceiling or other overhead obstruction shall be in accordance with Table 1004.3.1.
BOILER TOP CLEARANCES
|BOILER TYPE||MINIMUM |
FROM TOP OF
except where a greater clearance is required inthis table.
All boilers without manholes on top of the
where a greater clearance is required in thistable.
High-pressure steam boilers with steam generating
capacity not exceeding 5,000 pounds perhour.
High-pressure steam boilers with steam generatingcapacity exceeding 5,000 pounds per hour.
High-pressure steam boilers having heating surfacenot exceeding 1,000 square feet.
High-pressure steam boilers having heating surfacein excess of 1,000 square feet.
High-pressure steam boilers with input notexceeding 5,000,000 Btu/h.
High-pressure steam boilers with input inexcess of 5,000,000 Btu/h.
Steam-heating boilers and hot water-heatingboilers with input exceeding 5,000,000 Btu/h.
Steam-heating boilers exceeding 5,000 poundsof steam per hour.
Steam-heating boilers and hot water-heating
boilers having heating surface exceeding 1,000square feet.
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 pound per hour = 0.4536 kg/h, 1 Btu/hr = 0.293 W.
Boilers shall be mounted on floors of non-combustible construction, unless listed for mounting on combustible flooring.
Boiler rooms and enclosures and access thereto shall comply with the International Building Code and Chapter 3 of this code. Boiler rooms shall be equipped with a floor drain or other approved means for disposing of liquid waste.
Every boiler or modular boiler shall have a shutoff valve in the supply and return piping. For multiple boiler or multiple modular boiler installations, each boiler or modular boiler shall have individual shutoff valves in the supply and return piping.
Exception: Shutoff valves are not required in a system having a single low-pressure steam boiler.
The water supply to all boilers shall be connected in accordance with the International Plumbing Code.
Steam boilers shall be protected with a safety valve.
Hot water boilers shall be protected with a safety relief valve.
Pressure vessels shall be protected with a pressure relief valve or pressure-limiting device as required by the manufacturer's installation instructions for the pressure vessel.
Safety and safety relief valves shall be listed and labeled, and shall have a minimum rated capacity for the equipment or appliances served. Safety and safety relief valves shall be set at not greater than the nameplate pressure rating of the boiler or pressure vessel.
Safety or relief valves shall be installed directly into the safety or relief valve opening on the boiler or pressure vessel. Valves shall not be located on either side of a safety or relief valve connection. The relief valve shall discharge by gravity.
Safety and relief valve discharge pipes shall be of rigid pipe that is approved for the temperature of the system. High-pressure-steam safety valves shall be vented to the outside of the structure. The discharge piping serving pressure relief valves, temperature relief valves and combinations of such valves shall:
- Not be directly connected to the drainage system.
- Discharge through an air break located in the same room as the appliance.
- Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air break.
- Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
- Discharge to the floor, to the pan serving the boiler or storage tank, to a waste receptor or to the outdoors.
- Discharge in a manner that does not cause personal injury or structural damage.
- Discharge to a termination point that is readily observable by the building occupants.
- Not be trapped.
- Be installed so as to flow by gravity.
- Not terminate more than 6 inches (152 mm) above the floor or waste receptor.
- Not have a threaded connection at the end of such piping.
- Not have valves or tee fittings.
- Be constructed of those materials listed in Section 605.4 of the International Plumbing Code or materials tested, rated and approved for such use in accordance with ASME A112.4.1.
The power supply to the electrical control system shall be from a two-wire branch circuit that has a grounded conductor, or from an isolation transformer with a two-wire secondary. Where an isolation transformer is provided, one conductor of the secondary winding shall be grounded. Control voltage shall not exceed 150 volts nominal, line to line. Control and limit devices shall interrupt the ungrounded side of the circuit. A means of manually disconnecting the control circuit shall be provided and controls shall be arranged so that when deenergized, the burner shall be inoperative. Such disconnecting means shall be capable of being locked in the off position and shall be provided with ready access.
Low-water cutoff controls and flow sensing controls required by Section 1007.1 shall automatically stop the combustion operation of the appliance when the water level drops below the lowest safe water level as established by the manufacturer or when water circulation stops, respectively.
Steam boilers shall be equipped with bottom blowoff valve(s). The valve(s) shall be installed in the opening provided on the boiler. The minimum size of the valve(s) and associated piping shall be the size specified by the boiler manufacturer or the size of the boiler blowoff-valve opening. Where the maximum allowable working pressure of the boiler exceeds 100 psig (689 kPa), two bottom blowoff valves shall be provided consisting of either two slow-opening valves in series or one quick-opening valve and one slow-opening valve in series, with the quick-opening valve installed closest to the boiler.
Blowoff valves shall discharge to a safe place of disposal. Where discharging to the drainage system, the installation shall conform to the International Plumbing Code.
An expansion tank shall be installed in every hot water system. For multiple boiler installations, not less than one expansion tank is required. Expansion tanks shall be of the closed or open type. Tanks shall be rated for the pressure of the hot water system.
Exception: Expansion tanks shall not be required in the collector loop of drain-back systems.
Closed-type expansion tanks shall be installed in accordance with the manufacturer's instructions. Expansion tanks for systems designed to have an operating pressure in excess of 30 psi (207 kPa) shall be constructed and certified in accordance with the ASME Boiler and Pressure Vessel Code. The size of the tank shall be based on the capacity of the hot-water-heating system. The minimum size of the tank shall be determined in accordance with the following equation where all necessary information is known:
Vt = Minimum volume of tanks (gallons) (L).
Vs = Volume of system, not including expansion tanks (gallons) (L).
T = Average operating temperature (°F) (°C).
Pa = Atmospheric pressure (psi) (kPa).
Pƒ = Fill pressure (psi) (kPa).
Po = Maximum operating pressure (psi) (kPa).
Where all necessary information is not known, the minimum size of the tank shall be determined from Table 1009.2.
CLOSED-TYPE EXPANSION TANK SIZING
|SYSTEM VOLUME |
|TANK CAPACITIES IN GALLONS|
For SI: 1 gallon = 3.795 L.
Open-type expansion tanks shall be located not less than 4 feet (1219 mm) above the highest heating element. The tank shall be adequately sized for the hot water system. An overflow with a minimum diameter of 1 inch (25 mm) shall be installed at the top of the tank. The overflow shall discharge to the drainage system in accordance with the International Plumbing Code.
Every hot water boiler shall have a pressure gauge and a temperature gauge, or a combination pressure and temperature gauge. The gauges shall indicate the temperature and pressure within the normal range of the system's operation.
Every steam boiler shall have a water-gauge glass and a pressure gauge. The pressure gauge shall indicate the pressure within the normal range of the system's operation.
The gauge glass shall be installed so that the midpoint is at the normal boiler water level.
Upon completion of the assembly and installation of boilers and pressure vessels, acceptance tests shall be conducted in accordance with the requirements of the ASME Boiler and Pressure Vessel Code or the manufacturer's requirements, and such tests shall be approved. A copy of all test documents along with all manufacturer's data reports required by the ASME Boiler and Pressure Vessel Code shall be submitted to the code official.
An indicating test gauge shall be connected directly to the boiler or pressure vessel where it is visible to the operator throughout the duration of the test. The pressure gauge scale shall be graduated over a range of not less than one and one-half times and not greater than four times the maximum test pressure. Gauges utilized for testing shall be calibrated and certified by the test operator.