Bell & Gossett plate and frame heat exchangers offer maximum efficiency in less space, with outstanding application flexibility. Innovative plate design allows B&G heat exchangers to provide more heat transfer using less space. They perform with one-third to one-fifth the surface area of conventional shell and tube heat exchangers designed for the same application.

Contact Gritton & Associates to select a plate & frame heat exchangers.

What is ARI Standard 400-2001?

ARI Standard 400-2001 is a certification program established to define test requirements, rating requirements, conformance conditions and marking for liquid to liquid heat exchangers. The certification program entails annual testing of a sample of heat exchangers by an ARI approved testing laboratory. The test results are compared to the manufacturer’s published performance ratings. Certification and use of the ARI certification symbol is only granted to units that have met or exceeded the manufacturers’ published ARI logo © copyright ARI thermal performance rating. Failure to meet the test requirements requires re-rating or ceasing labeling of the failed product as ARI certified. ARI Standard 400-2001 provides a common method for evaluating the thermal performance of liquid to liquid heat exchangers. Specifying ARI Standard 400 certification allows buyers and end users to make equal comparisons between manufacturers.

Why do you need an ARI Standard 400-2001 Certified Heat Exchanger?

To ensure there is no “cheating” (see below) It’ll ensure the HVAC system is as energy efficient as possible. Three main components of a commercial HVAC system are the cooling tower, heat exchanger and chiller. These components work together as a system. The relationship of these components has a large effect on energy savings since a chiller’s efficiency improves with colder water. Given that energy prices are increasing every day, its very important to look at every component in a system to ensure that each one is saving as much energy as possible. It’s vital that each component performs as originally specified and promised by the manufacturer. This is why the Cooling Technology Institute (CTI) developed its certification program for cooling towers and ARI developed its certification programs for chillers and heat exchangers. If your cooling tower is CTI certified and your chiller is ARI certified, shouldn’t your heat exchanger be ARI certified also? ARI certified components, including the heat exchanger, might assist in obtaining LEED (Leadership in Energy and Environmental Design) certification. The commercial building industry is increasingly interested in constructing “green buildings” with LEED certification due to state and local government available incentives. One category that HVAC systems can impact LEED certification is Energy & Atmosphere. This category requires a reduction in the building energy consumption levels and has the greatest number of potential points towards LEED certification. It is estimated that a chiller’s energy efficiency increases 2% for every degree cooler the supply water is to the chiller. An ARI certified plate heat exchanger ensures that the chiller receives water at the temperature specified. The engineer can then specify closer temperature approaches and be confident that what is specified is what the plate heat exchanger will provide. An ARI certified plate heat exchanger might result in cost savings for the end-user. For example, assuming a free cooling application with a typical 250 ton chiller load and a rate of $0.10/KW, the end-user will save a minimum of $20/hr for every hour the chiller is not running. An installation utilizing a plate heat exchanger for “free cooling” where the heat exchanger was selected by “cheating” will result in the chiller(s) being started sooner and left on longer than an ARI certified plate heat exchanger.

What do you mean by "cheating"?

Due to the ability of plate type heat exchangers to achieve close temperature approaches with high heat transfer rates, altering the design temperatures by even tenths of a degree or understating the pressure drops can significantly reduce the amount of surface area required and therefore, cost of the heat exchanger. Many times this “cheating” is done by our competitors but not disclosed to the buyer or end-user. In some cases, this results in units with as much as 30% less surface area. To alleviate this practice, members of ARI’s Liquid to Liquid Heat Exchanger committee developed Standard 400. Though members included delegates from ITT, Alfa Laval, Tranter and FlatePlate, only ITT and one other manufacturer obtained their certification. For anyone who has struggled to compete on a level playing field when proposing GPX plate & frame heat exchangers, specifying ARI Standard 400 will help ensure an “apples to apples” comparison. Below is an example of altering design conditions and its impact on size and cost. Here, a ten degree delta T and two degree approach has been specified by the buyer. Based on the above temperatures, the Log Mean Temperature Difference (LMTD) = 2.0 °F. If the flow rate is 1000 GPM for each fluid, the calculated heat load (Q) is 5,000,000 btu/hr. For a plate type heat exchanger, lets assume the heat transfer coefficient (U) will be approximately 1200 btu/ft2*h*F. Using the basic heat transfer equation where Area = Q / (U * LMTD), the area required is 2083 ft2. Now if the approach is altered to 2.2 degrees or T2 = 45.2 °F, the new LMTD = 2.2 °F. Assuming all else is constant, the Area required is now 1893 ft2, approximately 10% less. If the approach is further altered to 2.3 degrees, the Area required is 1812 ft2, approximately 15% less. This example shows how altering the temperatures by just a few tenths of a degree when making a selection, reduces the area required and therefore the cost of the heat exchanger. Similar logic can be followed through for “cheating” on the pressure drops. Combine “cheating” on both the temperature approach and pressure drop, one can see how the required area and cost could be as much as 30% less than that of a manufacturer who does not. Some plate manufacturers, without the buyer or end user’s knowledge, engage regularly in this practice. In summary, LMTD (°F) Area reqd. (ft2) Cost Index 2.0 2083 1.00 2.2 1893 0.95 2.3 1812 0.93 2.5 1667 0.87