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The Importance of AHRI Standard 400

Originally published
Originally published: 7/1/2016

Your commercial customers rely on you for proper performance and unfailing systems.


Specifying the correct heat exchanger for a facility will maximize system efficiency and prolong the life of the system.

It is important that HVACR professionals are educated on the importance of specifying reliable, high-performing equipment for owners and contractors of commercial building systems.

In November 2015, the Air-Conditioning, Heating and Refrigeration Institute (AHRI) released an updated "Standards for Performing Rating of Liquid-to-Liquid Heat Exchangers," for the testing, rating and marking of such products used in the HVACR industry.

The standard ensures all manufacturers are designing to the same tolerances providing a reliable comparison of equipment.

The AHRI 50-year legacy provides building owners, contractors and manufacturers in the HVACR and water heating industry with an independent third-party certification of performance ratings through annual testing.

The verified design for the heat exchanger selection ensures performance as specified, which protects the customer and engineer on startup, eliminates the need for field testing and allows system operation with optimal energy efficiency.

What tolerances does AHRI require the manufacturer meet during its performance testing?

AHRI developed testing requirements more stringent than those traditionally used in the HVACR industry to recognize the use in high-energy-efficient solutions with close temperature approaches and high-efficiency pumps.

During testing intervals specified by AHRI, the manufacturers stated performance for a given test must meet the following requirements:

Total Heat Transfer Rate is greater than (>=) 95% of published value Tested Pressure Drop less than (<=) 115% of published value

How is an HVAC System Defined?

In the ANSI/AHRI Standard 400 LLHE Operations Manual, HVAC is defined as "applications encompassing equipment located in a residential or commercial building exclusively used for conditioning spaces for the occupants of the building."

What is the scope of the ANSI/AHRI Standard 400 program?

The scope of the ANSI/AHRI Standard 400 program is defined as:

• For gasketed plate type heat exchangers

• Utilizing water or sea water (glycols are not yet included)

• With a capacity less than or equal to 24,000,000 btu/hr

• And flow rate less than or equal to 2,000 gpm

Why is AHRI Standard 400 Important?

AHRI certification ensures a manufacturer's stated product performance will be met and operate as designed, thus enhancing buyer and building operation confidence.

• Ensures all manufacturers are designing to the same tolerances, providing buyers a reliable comparison of equipment.

• Promotes energy savings. For example, in a "free cooling/waterside economizer" application, this could mean the chiller will run less, resulting in energy savings.

• AHRI certification can facilitate compliance to various state and federal efficiency regulations.

• ASHRAE Standard 90.1 requires waterside economizers to comply with AHRI Standard 400 beginning with 2010 version.

• U.S. Green Building Council's LEED program references ASHRAE Standard 90.1.

• International Energy Conservation Code registers compliance with ASHRAE Standard 90.1.

• Most AHRI certification programs, including AHRI Standard 400 for liquid-to-liquid plate and frame heat exchangers, require members to quote an AHRI-certified model/design when the application is within the scope of the program.

What are "Certify All" Requirements of AHRI?

Almost all AHRI certification programs, including the Liquid-to-Liquid Heat Exchanger AHRI Standard 400, have a "certify all" requirement.

• Certify all requires manufacturers that have AHRI certifications for its product to quote and provide an AHRI-certified design when the application falls within the AHRI program scope, application definition and intended market.

• The scope, application definition and market are defined above.

• The certify-all requirement is necessary, regardless if the specification, user, buyer, etc. requires an AHRI certified design or not, and applies to all participating manufacturers of the AHRI certification program.

How does one specify gasketed plate heat exchangers based on the above information?

If writing a specification, it is recommended to add clarification to avoid any interpretations or opinion. This will help ensure "apples to apples" comparisons.

• Specify that acceptable manufacturers are: Certified participating members of the AHRI Liquid to Liquid Heat Exchanger Certification Program based on ANSI/AHRI Standard 400.

• Manufacturer must have AHRI LLHE certification to offer an AHRI certified model.

• A manufacturer can be a member of AHRI but not participate in or have AHRI LLHE certification, hence should not be considered equivalent to members with AHRI LLHE certification.

• Statements such as "in accordance with," or similar, are not the same as AHRI certified.

• If the application is within the AHRI scope, meets the AHRI definition for HVAC equipment and is being sold into the intended market:

o Require an AHRI certified model to be listed in the schedule.

• If the fluids or heat load or flow rates are outside the scope of the AHRI LLHE certification program, add clarification to the specification that:

o Accepted manufacturer must have AHRI LLHE certification, even though model offered cannot be AHRI certified due to being out of scope.

o Manufacturer must design to the tolerances required in AHRI Standard 400 for heat transfer and pressure drop.

The AHRI Product Performance certification programs are voluntary programs administered and governed by AHRI, which ensure that various type of HVACR and water heating equipment performs according to manufacturers' published claims.

Products certified through the programs are continuously tested at the direction of AHRI by an independent third-party laboratory under contract to AHRI to determine the product's ability to conform to one or more product rating standard or specification.

Working with AHRI, development continues to expand and improve the program to support energy savings, improve productivity and ensure a better environment.


John Boyer is the Heat Transfer Market Manager at Xylem Inc. He holds a bachelor of science degree in chemical engineering from the University at Buffalo and Six Sigma Green Belt certification, Lean, from the University of Michigan College of Engineering. For additional information, visit or


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