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Minnesota Mechanical Code Q & A

This Q & A was developed to help quickly address some basic questions about the Minnesota Mechancial Code.

Please note that although the Minnesota Mechanical Code affects both residential and commercial applications, this Q & A was developed to address changes affecting residential construction only.

Q. When did the Minnesota Mechanical Code take effect?

A. The effective date for the Minnesota Mechanical Code is September 20, 2004.

Q. Why did the mechanical requirements change?

A. Minnesota's residential mechanical requirements had not been updated since 1994. Technologies in the HVAC industry have changed dramatically during this time, impacting installation requirements. Usually, national model codes are revised on a three-year cycle to reflect these changes. Minnesota is moving toward becoming current with nationally accepted codes.

Q. What are the key areas of change in the Minnesota Mechanical Code?

A. The Minnesota Mechanical Code requirements can affect nearly all of the permanently installed mechanical systems in new and existing buildings. However, the key areas of change that have the most widespread effect on residential builders, subcontractors and homeowners are make-up air, combustion air, duct sizing and duct sealing.

Q. What are the ventilation air requirements?

A. Ventilation requirements are not a part of the Minnesota Mechanical Code at this time. For now, ventilation requirements will remain in the Minnesota Energy Code. Ventilation air is necessary to provide fresh air for occupants of a house and for moisture control and dilution of contaminants. Mechanical ventilation is required in all new residential construction. This can be accomplished with a properly sized exhaust system, a balanced ventilation system such as a Heat Recovery Ventilation system (HRV), or other approved methods.

Q. What are the highlights of the make-up air requirements?

A. Make-up air is necessary to replace air removed by exhaust equipment. Lack of sufficient make-up air can cause depressurization, which can result in increased garage infiltration, performance problems for other mechanical equipment and callbacks. Contractors will now be able to manage equipment compatibility, choices and costs during the planning process.
To easily compare multiple scenarios, use our Mechanical Code GuidelinesTM   software, or refer to the worksheet and reference tables in the Minnesota Mechanical Code.

Q. What are the combustion air requirements?

A. Combustion air is often confused with make-up air, but they are completely independent of each other. Combustion air is the air needed for space heating, water heating, and for fireplaces to turn fuel into heat. The combustion air requirements reflect nationally accepted methods and the latest industry research. To simplify calculations, use our Mechanical Code GuidelinesTM  software, or refer to the worksheet and reference tables in the Minnesota Mechanical Code.

Q. What are the requirements for duct sizing and sealing?

A. Ducts must be sized using ACCA Manual D, or an equivalent approved method. Ducts must be sealed, without visible gaps, in accordance with the SMACNA HVAC Duct Construction Standards, Metal and Flexible manual. These changes primarily clarify the intent of prior Code language and reflect accepted industry standards.

Q. How does the Minnesota Mechanical Code benefit the home building industry?

A. The biggest benefit is simplicity. Although there are still many factors to consider when building a new home, the Minnesota Mechanical Code clarifies current requirements, updates installation information for new technologies and provides helpful tools such as tables and worksheets to help manage first costs and safety concerns.

Q. How does the Minnesota Mechanical Code benefit homeowners?

A. Two of the biggest benefits to homeowners are more options and more cost effective solutions for their equipment needs. For instance, now there are more options available in natural gas water heaters: power vent, direct vent or atmospheric vent.

Q. What is an atmospheric vent water heater?

A. These are the standard gas water heaters that have been serving millions of customers for years. They use room air for combustion and exhaust and are vented through the roof. Under the Minnesota Mechanical Code,
atmospheric vent water heaters are an option for one- and two-family dwellings.

Q. Is there an easy way for me to learn what my mechanical requirements are for specific homes that I am building?

A. There are a number of resources you can access. Our Mechanical Code GuidelinesTM  software can help you quickly and accurately figure new mechanical requirements. Simply input specific information about the home you're building and let the software do the calculations for you. You can use our Online Make-Up Air Calculator until you receive the full version of Mechanical Code Guidelines software. For links to other helpful information, refer to Mechanical Code Resources.

Q. Does the Mechanical Code Guidelines software work together with the old Guide Lines software I received in 2000 when the Energy Code changed?

A. The original Guide Lines software was designed to assist industry professionals in building to the Minnesota Chapter 7672 Energy Code. If you do not build to Chapter 7672, you may uninstall this software from your computer. The Mechanical Code Guidelines software will assist you in determining compliance with requirements in the Minnesota Mechanical Code for make-up air, combustion air and the ventilation air requirements in the Minnesota Energy Code.

If you have additional questions, please contact your account representative or visit Mechanical Code Resources.

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