CODES

ADOPTS WITH AMENDMENTS:

International Mechanical Code 2012 (IMC 2012)

Copyright

Important Disclaimer

2015 Minnesota Building Code Administration

2015 Minnesota Mechanical Code

Chapter 1 Scope and Administration

Chapter 2 Definitions

Chapter 3 General Regulations

Chapter 4 Ventilation

Chapter 5 Exhaust Systems

Chapter 6 Duct Systems

Chapter 7 Combustion Air

Chapter 8 Chimneys and Vents

Chapter 9 Specific Appliances, Fireplaces and Solid Fuel-Burning Equipment

Chapter 10 Boilers, Water Heaters and Pressure Vessels

Chapter 11 Refrigeration

Chapter 12 Hydronic Piping

Chapter 13 Fuel Oil Piping and Storage

Chapter 14 Solar Systems

Chapter 15 Referenced Standards

Chapter 16 Installation and Testing of Oil or Liquid Fuel-Fired Equipment

Appendix A Chimney Connector Pass-Throughs

Appendix B Recommended Permit Fee Schedule

2015 Minnesota Ashrae

Informative Appendix A— Examples of Air Balancing

Informative Appendix B— Alternative Airflow Calculation Method

Informative Appendix C— Hood Energy Savings Calculation

Informative Appendix D— Using Ashrae Standard 154 to Determine Hood Overhangs and Exhaust Airflows

Informative Appendix E— Informative Bibliography

This chapter shall govern the installation, alteration, and repair of boilers, water heaters, and pressure vessels.

Exceptions:

1. Pressure vessels used for unheated water supply.

2. Portable unfired pressure vessels and Interstate Commerce Commission containers.

3. Containers for bulk oxygen and medical gas.

4. 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.

5. Pressure vessels used in refrigeration systems that are regulated by IMC Chapter 11.

6. Pressure tanks used in conjunction with coaxial cables, telephone cables, power cables, and other similar humidity control systems.

7. Any boiler pressure vessel under the direct jurisdiction of the United States.

Anyone who installs a boiler must ensure that the boiler is inspected by the Department of Labor and Industry after installation is complete and before the boiler is placed in operation if the individual or combined Btu input exceeds:

A. 100,000 Btu/hr for steam boilers;

B. 500,000 Btu/hr for hot water supply boilers; or

C. 750,000 Btu/hr for hot water heating boilers.

Boilers utilizing fuel gas systems with Btu/hr inputs that are rated at or below items A to C shall comply with Section 631 of the 2012 IFGC.

Exceptions: Boilers identified in Minnesota Statutes, Section 326B.988, including the following, are not subject to this section:

1. Boilers in buildings occupied solely for residential purposes with accommodations for not more than five families.

2. Boilers under the direct jurisdiction of the United States.

3. Boilers located on farms used solely for agricultural or horticultural purposes; for the purposes of this subpart, boilers used for mint oil extraction are considered used for agricultural or horticultural purposes, provided that the owner or lessee complies with the inspection requirements contained in Minnesota Statutes, Section 326B.958.

The owner of a pressure vessel not specifically exempted by Minnesota Statutes, Section 326B.988, must ensure that the pressure vessel is inspected by an insurance company authorized to do business in the state or the Department of Labor and Industry at least every two years.

Exceptions: Pressure vessels identified in Minnesota Statutes, Section 326B.988, including the following, are not subject to this subpart:

1. Pressure vessels in buildings occupied solely for residential purposes with accommodations for not more than five families.

2. Pressure vessels under the direct jurisdiction of the United States.

3. Pressure vessels located on farms used solely for agricultural or horticultural purposes; for the purposes of this section, boilers used for mint oil extraction are considered used for agricultural or horticultural purposes, provided that the owner or lessee complies with the inspection requirements contained in Minnesota Statutes, Section 326B.958.

Pursuant to Minnesota Rules, Chapter 5230, and Minnesota Statutes, Sections 326B.90 to 326B.925, high-pressure piping for boilers shall be regulated by the Department of Labor and Industry for the following operating conditions:

A. Steam systems operating over 15 psi; or

B. Hot water or other heating medium operating over 30 psi and 250°F.

Potable water heaters and hot water storage tanks shall be listed and labeled and installed in accordance with the manufacturer’s installation instructions, the International Plumbing Code and this code. All 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. Thermal solar water heaters shall comply with Chapter 14 and UL 174 or UL 1453.
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 installation 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 installation instructions.
All pressure vessels shall be in accordance with the ASME Boiler and Pressure Vessel Code, shall bear the label of an approved agency and shall be installed in accordance with the manufacturer’s installation instructions.
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 boilers and pressure vessels shall be performed by approved welders in compliance with the ASME Boiler and Pressure Vessel Code Section IX and the National Board Inspection Code.
Oil-fired boilers and their control systems shall be listed and labeled in accordance with UL 726 or shall utilize burner assemblies and control systems listed and labeled in accordance with UL 296 and shall be installed in accordance with NFPA 31 and the manufacturer’s installation instructions. Electric boilers and their control systems shall be listed and labeled in accordance with UL 834. Boilers with an input rating above 400,000 Btu/hr (3660 kW) shall be designed and constructed in accordance with the standards referenced in Minnesota Statutes, Section 326B.964, as applicable.
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 in accordance with Minnesota Rules, parts 1346.1601 to 1346.1606. A complete control diagram together with complete boiler instructions shall be furnished 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. When 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.

TABLE 1004.3.1
BOILER TOP CLEARANCES

BOILER TYPEMINIMUM
CLEARANCES
FROM TOP OF
BOILER TO
CEILING OR
OTHER
OVERHEAD
OBSTRUCTION
(feet)
All boilers with manholes on top of the boiler
except where a greater clearance is required in
this table.
3
All boilers without manholes on top of the boiler
except high-pressure steam boilers and where a
greater clearance is required in this table.
2
High-pressure steam boilers with steam generating
capacity not exceeding 5,000 pounds per hour.
3
High-pressure steam boilers with steam generating
capacity exceeding 5,000 pounds per hour.
7
High-pressure steam boilers having heating surface
not exceeding 1,000 square feet (93 m2).
3
High-pressure steam boilers having heating surface
in excess of 1,000 square feet (93 m2).
7
High-pressure steam boilers with input not
exceeding 5,000,000 Btu/h (1465 kW).
3
High-pressure steam boilers with input in
excess of 5,000,000 Btu/h (1465 kW).
7
Steam-heating boilers and hot water-heating
boilers with input exceeding 5,000,000 Btu/h (1465 kW).
3
Steam-heating boilers exceeding 5,000 pounds
of steam per hour (2268 kg/h).
3
Steam-heating boilers and hot water-heating
boilers having heating surface exceeding 1,000
square feet (93 m2).
3
For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 pound per hour = 0.4536 Kg/h.
Equipment shall be set or mounted on a level base capable of supporting and distributing the weight contained thereon. Boilers, tanks and equipment shall be secured in accordance with the manufacturer’s installation instructions.
Boilers shall be mounted on floors of noncombustible 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.
Hot water and steam boilers shall have all operating and safety controls set and operationally tested by the installing contractor. A complete control diagram and boiler operating instructions shall be furnished by the installer for each installation.
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.
All steam boilers shall be protected with a safety valve.
Hot water boilers shall be protected with a safety relief valve.
All 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 meet the requirements of Section I, IV or VIII of the ASME Boiler and Pressure Vessel Code, as applicable. All boilers and pressure vessels shall have a safety relief valve stamped with the ASME code symbol and shall be set no higher than the maximum allowable working pressure of the pressure vessel. Safety relief valves shall have a rated volumetric capacity greater than the boiler or pressure vessel can produce at nameplate pressure and shall have a nonadjustable pressure set point below the rating of the boiler or pressure vessel capable of relieving all excess pressure at its pressure set point. Safety and safety relief valves shall have a manual method to test the valve, without endangering the operator, to ensure proper mechanical operation of the valve.
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 and pressure of the system. The discharge pipe shall be no smaller than the diameter of the safety or relief valve outlet and the discharge end shall be reamed and unthreaded. Safety and relief valves shall not discharge so as to be a hazard, a potential cause of damage, or otherwise a nuisance and shall terminate within 18 inches (457 mm) of the floor. High-pressure steam safety valves shall be vented to the outside of the structure in accordance with Minnesota Rules, parts 5225.4100 and 5230.0990 on boilers, pressure vessels, and high-pressure piping under the jurisdiction of the Department of Labor and Industry, as applicable. Where a low-pressure safety valve or a relief valve discharges to the drainage system, the installation shall conform to the Minnesota Plumbing Code, Minnesota Rules, Chapter 4715.
Boilers shall be equipped with controls and limit devices as required by the manufacturer’s installation instructions and the conditions of the listing.
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.
A manually operated remote shutdown switch shall be located as required by ASME CSD-1.

Exception: A single hot water boiler with a rated input of less than 400,000 Btu/hr (117 kW).

Steam and hot water boilers shall be protected with a low-water fuel cutoff control to stop the combustion operation when the water level drops below the lowest safe permissible water level in accordance with the following items:

1. An automatically fired hot water boiler or group of boilers piped together having a rated input of 400,000 Btu/hr (117 kW) or above shall be equipped with an automatic low-water fuel cutoff to stop the combustion operation before the water level drops below the lowest safe permissible water level established by the boiler manufacturer.

2. A boiler installed at an elevation where all radiation in the system is below the lowest safe permissible water level shall be equipped with an automatic low-water fuel cutoff to stop the combustion operation when the water level drops below the lowest safe permissible water level established by the boiler manufacturer.

3. A low-water fuel cutoff shall be installed when recommended by the manufacturer’s installation instructions or listing and when special consideration and installations will require a low-water fuel cutoff to protect a hot water or steam boiler.

4. A means shall be provided for testing the operation of the low-water fuel cutoff without requiring the entire system to be drained.

5. A watertube or coil-type boiler requiring forced circulation to prevent overheating of the tubes or coils shall have a flow-sensing device installed, in lieu of the low-water fuel cutoff, to automatically stop the combustion operation when the circulating flow is interrupted.

The low-water cutoff 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.
Every steam boiler shall be equipped with a quick-opening blowoff valve. The valve shall be installed in the opening provided on the boiler. The minimum size of the valve shall be the size specified by the boiler manufacturer or the size of the boiler blowoff-valve opening.
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, a minimum of 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.
Closed-type expansion tanks shall be installed in accordance with the manufacturer’s instructions. 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:
(Equation 10-1)

For SI:

where:

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).
Pf = Fill pressure (psi) (kPa).
Po = Maximum operating pressure (psi) (kPa).
Open-type expansion tanks shall be located a minimum of 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 Minnesota Statutes, Sections 326B.958 and 326B.966. Where field assembly of pressure vessels or boilers is required, a copy of the completed Manufacturer’s Data Report required by the ASME Boiler and Pressure Vessel Code shall be submitted to the building official.

Exception: For all ammonia refrigeration systems, refer to Minnesota Rules, Chapter 5230.

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. All gauges utilized for testing shall be calibrated and certified by the test operator.
Resources