Specifying... Or Equal

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1 This article was published in ASHRAE Journal, August Copyright 2014 ASHRAE. Posted at This article may not be copied and/or distributed electronically or in paper form without permission of ASHRAE. For more information about ASHRAE Journal, visit Specifying... Or Equal BY KENNETH M. ELOVITZ, P.E., ESQ., MEMBER ASHRAE When designing an HVAC system, one key element of an engineer s responsibility is to prepare plans and specifications that provide the level of information reasonably required to construct the project in conformance with applicable codes and sound design practice. That responsibility usually means showing one way to make the system work. The plans and specifications also must be sufficiently free of ambiguity that the contractors and their suppliers can discern the design intent. Engineers typically meet that requirement by identifying the major equipment that makes up the basis of design for the job by make and often model. In an effort to promote competition, specifications often let the contractor use products that are equal to the products that are the basis of design. Sometimes the specification identifies a product and says or equal. Sometimes the specification identifies more than one manufacturer whose products are acceptable. Even when manufacturers are listed as acceptable, it is important to say, or equal by... There can easily be cases where an acceptable manufacturer s product does not provide performance equal to the specified product. The contractor s motivation to propose an equal is not necessarily a desire to cheapen the job. There are legitimate business reasons a contractor might want to use a brand of equipment different from the brand the engineer used as the basis of design. Those reasons include: Familiarity with the product, which potentially translates into fewer labor hours and lower cost. A history of better service from the supplier or representative, including schedule and delivery considerations. Better pricing, which translates to a lower bid and ultimately a lower project cost for the owner. Equal does not mean identical. Part of a manufacturer s job is to differentiate its products from its competitors products. That differentiation might come in the form of subtle differences in design or materials of construction. Engineers evaluating proposed equals often have to rule on whether those differences are functional differences (making the products not equal) or mere product differentiation (making the products functionally equivalent or equal ). Many construction contracts incorporate AIA A , General Conditions of the Contract for Kenneth M. Elovitz, P.E., Esq., is a professional engineer at Energy Economics, Inc., in Foxboro, Mass. 54

2 Construction. Sections , , and of that document give the architect (or his designee) the authority to interpret performance requirements of the contract. That authority to interpret extends to evaluating equals. But A201 does not provide any guidance on how to exercise that authority. Another standard form contract, Document C-700, Standard General Conditions of the Construction Contract (2007 edition), prepared by the Engineers Joint Contract Documents Committee (EJCDC) provides some guidance. Although EJCDC C-700 is not often used for building construction projects, the following language from that document can help engineers determine when a proposed product is equal (see sidebar, EJCDC C-700, 6.05, Substitutes and Or-Equals ). Equal or Substitution A proposed equal is not a substitution. A substitution is tantamount to a design change it proposes to achieve the same or a different result with different equipment or a different technology. A proposal to use a chiller with a screw compressor instead of a centrifugal compressor uses a different technology so would be a substitution, not an equal. Strictly speaking, a substitution requires a change order. A proposal to use an in-line pump instead of an end suction pump, even with identical performance, would likewise be a substitution, not an equal, because the proposed in-line pump is different in kind or type from the end suction pump that is the basis of design. For the most part, equals consist of the same type of product from a different manufacturer. Is It Equal? The following discussion highlights some of the considerations engineers face when determining whether a submitted product is equal to the product that is the basis of design. Example 1: End Suction Pump An engineer selected an end suction pump to deliver 130 gpm at a head of 65 ft (8 L/s at 194 kpa) and chose manufacturer Red as the basis of design. The engineer incorporated Red s guide specification into the project specifications. Various bidders submit pumps from manufacturers Blue and Green as proposed equals. The engineer must decide whether Blue and Green are equal to Red. EJCDC C-700, 6.05, Substitutes and Or-Equals A. Whenever an item of material or equipment is specified or described in the Contract Documents by using the name of a proprietary item or the name of a particular Supplier, the specification or description is intended to establish the type, function, appearance, and quality required. Unless the specification or description contains or is followed by words reading that no like, equivalent, or or-equal item or no substitution is permitted, other items of material or equipment or material or equipment of other Suppliers may be submitted to Engineer for review under the circumstances described below. 1. Or-Equal Items: If in Engineer s sole discretion an item of material or equipment proposed by Contractor is functionally equal to that named and sufficiently similar so that no change in related Work will be required, it may be considered by Engineer as an or-equal item, in which case review and approval of the proposed item may, in Engineer s sole discretion, be accomplished without compliance with some or all of the requirements for approval of proposed substitute items. For the purposes of this Paragraph 6.05.A.1, a proposed item of material or equipment will be considered functionally equal to an item so named if: a. in the exercise of reasonable judgment Engineer determines that: 1) it is at least equal in materials of construction, quality, durability, appearance, strength, and design characteristics; 2) it will reliably perform at least equally well the function and achieve the results imposed by the design concept of the completed Project as a functioning whole; and 3) it has a proven record of performance and availability of responsive service. b. Contractor certifies that, if approved and incorporated into the Work: 1) there will be no increase in cost to the Owner or increase in Contract Times; and 2) it will conform substantially to the detailed requirements of the item named in the Contract Documents. Information in the project specifications constitutes contract requirements that the contractor must meet. Additional information or features described in the manufacturer s data sheets are probably not enforceable as contract requirements. If they were important to the project, they would be in the specs. Table 1 compares various properties of the three pumps and gives rise to the following observations and analysis of some of the feature differences. Evaluation as an AUGUST 2014 ashrae.org ASHRAE JOURNAL 55

3 equal depends on the application. Some of the features discussed below might have performance implications in one application but not another. Analysis The specification calls for Grade 30 cast iron, so Green s pump casing should be OK as an equal. The grade of cast iron relates to strength, so Blue would have to show that the close grain cast iron it uses has performance equal to or better than Grade 30 cast iron. It is probably OK to rely on Green s product data sheet to conclude that Green s pump is rated for 175 psi (1206 kpa), like Red s. However, to be an equal, Blue would have to show that the rating of its casing is at least 175 psi (1206 kpa). The specification calls for a stainless steel shaft, based on Red s guide spec. However, Red s data sheet identifies Red s shaft as a grade of carbon steel, not stainless steel. Since Red is the basis of design, the requirement for a stainless steel shaft probably has to be waived for Red and for the other TABLE 1 Pump manufacturer comparison. MAKE BLUE GREEN RED MODEL LF FI e-1510 GUIDE SPEC CASING SPEC Close Grain Cast Iron Class 30 Cast Iron Class 30 Cast Iron IMPELLER SPEC Lead Free Bronze Bronze Stainless SHAFT SPEC Carbon Alloy Stainless 2 BEARING TYPE Ball Ball Rolling Contact BALANCING (FACTORY) Not Stated Grade G6.3 Grade G6.3 SEAL TEMPERATURE RATING Not Stated 250 F 225 F WORKING PRESSURE Not Stated Not Stated 175 psi DATA SHEET CASING DATA SHEET A48 Class 30 A48 Class 30 A48 Class 30 IMPELLER DATA SHEET SHAFT DATA SHEET manufacturers. Astute engineers will check and edit manufacturers guide specs to be sure they do not call for features not applicable to or necessary for the job. With regard to the impeller, is Red s choice of stainless steel a functional consideration or a matter of product differentiation? In a closed loop HVAC system with proper water treatment, the bronzes probably have corrosion resistance and durability equal to Red s stainless steel impeller. Engineers should not back door flat spec Red by enforcing the requirement for a stainless steel impeller. Likewise, if Blue or Green were the basis of design, it would not be appropriate to reject Red on the basis that its impeller is stainless steel instead of bronze. On the other hand, if the chemistry of the circulating fluid makes the composition of the impeller an important consideration, B584/C87600 B21 Silicon Bronze AISI % C (90 ksi yield) B Bronze 1 Leaded Red Brass A743 Gr CF8 Type 304 AISI % C (45 ksi yield) ASTM 108 Gr 1144 (90 ksi yield) WEAR RING Tin Bronze, B (B18) Optional Not Stated WORKING PRESSURE Not Stated 175 psi Not Stated SELECTION FOR 130 GPM AT 65 FT RATED RPM 1,775 1,760 1,750 BHP EFFICIENCY 65.0% 61.0% 67.6% Right of Peak Efficiency Right of Peak Efficiency Left of Peak Efficiency 1 Manufacturer s literature says bronze, but the alloy designation is leaded red brass. Strictly speaking, brass is a type of bronze. 2 Guide spec says stainless steel, but the alloy listed on the data sheet is not a stainless steel. that requirement should be stated clearly in the specification. Blue and Green provide ball bearings, which meets the requirement for rolling contact bearings in the specifications based on Red s guide spec. What if the Blue or Green were the basis of design and Red s rolling contact bearings are sleeve bearings not ball bearings? Is Red an equal? Maybe not, if the engineer specified ball bearings and there is an engineering reason to prefer ball bearings over sleeve bearings in this application. Red s pump is the most efficient of the three. Unless efficiency is clearly stated as an important feature of the basis of design, the slight increase in Blue s brake horsepower (3.28 vs. Red s 3.23 [2.45 vs kw]) is probably not enough to say Blue is not equal. Green s lower efficiency results in 3.51 bhp (2.62 kw). If motor efficiency 56

4 is 90% and the pump operates 6,000 hours/year at constant speed, Green s pump will use 1,400 kwh/year ($210 at $0.15/kWh) more than Red s. Is that enough of a difference to say Green s pump is not equal? A close call. The call gets even closer if the pump will operate at variable speed because the operating cost difference gets much smaller in absolute kwh or dollars. My conclusion: If Red is the basis of design, Blue is an equal as long as Blue can show that its casing meets the 175 psi (1206 kpa) rating. Green is an equal if the operating cost difference is small enough to be insignificant; otherwise, Green is not equal. Example 2: Air-Cooled Chiller An engineer designs a chilled water system that requires 132 gpm (8.33 L/s) of water at 44 F (6.67 C) supply, returning at 56 F (13 C), for a load of 66 tons (232 kw). The schedule page of the drawings lists those criteria and says nominal 70 tons in a column titled capacity. A note says Design Based on New York. Various bidders submit chillers by other manufacturers. Table 2 compares key features of nominal 70 ton (246 kw) chillers from four manufacturers. Are the other three chillers equal to New York s nominal 70 ton chiller for this application? Analysis The job criteria call for 66 tons of cooling capacity, but the schedule also identifies the chiller as nominal 70 tons. Does Minnesota s chiller comply, even though it delivers only 64 tons (225 kw)? Minnesota could almost certainly deliver the stated capacity with the next size chiller, but most likely at higher cost. An aggressive contractor could argue that because the schedule says nominal 70 tons, Minnesota s chiller qualifies as an equal. Engineers are not expected to know the ins and outs of every product a contractor might propose for a job. Engineers might avoid this type of problem if the plans and specifications clearly identify what information relates to performance (so represents required features) vs. what information is provided to help the contractor identify the product the engineer used as the basis of design. Suppose Minnesota s chiller was the basis of design. New York s chiller has a higher evaporator pressure drop so might change the pump selection. Does that mean New York is not equal to Minnesota? Perhaps. Is evaporator pressure drop a sneaky way to list New York as an TABLE 2 Chiller comparison. MANUFACTURER New York Minnesota Wisconsin Pennsylvania MODEL 30RAP070 AGZ070D CGAM070 YLAA0070SE NOM. TONS AHRI TONS AHRI COMPR KW 75.1 Not Given Not Given Not Given AHRI FAN KW 6.4 Not Given Not Given Not Given AHRI TOTAL KW FL KW/TON FULL LOAD EER IPLV NOMINAL GPM COOLER PD (FT) Not Given 12.5 REFRIGERANT R-410A R-410A R-410A R-410A NUMBER OF COMPRESSORS MCA (460/3) MOCP (460/3) ICF (460/3) Not Given Not Given Not Given REC. FUSE (460/3) Not Given 175 SPL DB-A Not Given 65 Not Given Not Given CABINET CABINET COOLER CONDENSER Galvanized With Baked Enamel Powder Coat or Prepaint Passes B Hour Salt Spray Test Brazed Type 316 Stainless Tube/ Fin With Corrosion Resistant Coating Painted Passes B Hour Salt Spray Test Brazed Stainless Copper Tube/ Fin Galvanized With Powder Coat Brazed Stainless Copper Tube/ Fin Galvanized With Powder Coat 1000 Hour B117 Salt Spray Test w/ D1654 Rating of 6 Brazed Stainless Coils and Fins Same Material (Type Not Stated) DISCHARGE SERVICE VALVES Yes Not Stated Not Stated Yes acceptable manufacturer but effectively exclude its chiller? A better solution for the success of the job might be to include language in the specifications that explicitly makes contractors responsible for design changes that flow from their choice of proposed equals to the product that is the 58

5 basis of design. That way, the engineer could accept New York s chiller and make the contractor responsible to adjust the pump selection, probably with a minor impeller size change, to accommodate the contractor s preferred vendor. Minnesota s chiller has a painted steel cabinet. The others have painted or powder coated galvanized steel cabinets. Is a galvanized steel substrate key to the success of the job? It might be, if the chiller will be in a corrosive environment like near water or in an industrial area. If so, Minnesota is not equal, but the requirement for galvanized steel should be specified up front, not used as a secret weapon to exclude Minnesota. New York s condenser is aluminum tube with aluminum fins. Pennsylvania says its condenser tubes and fins are of the same material to avoid galvanic corrosion but does not identify the material. Most likely it is aluminum, but Pennsylvania would have to identify the tube and fin material if submitted as an equal to New York. What about Minnesota and Wisconsin with their copper tube/aluminum fin condensers? Most engineers would say copper tubes are better than aluminum based on thermal conductivity and ease of repair. The long, successful history of copper tube/aluminum fin coils, both evaporator and condenser, says that the potential for galvanic corrosion between those materials in air coil applications should not disqualify Minnesota and Wisconsin as equals. New York s chiller requires a minimum circuit ampacity (MCA) of amps and maximum overcurrent protection (MOCP) of 175 amps. Pennsylvania s chiller requires the next larger size circuit (MCA of 179 amps/mocp of 200 amps). If Pennsylvania is accepted as equal, who pays for the increase in electric circuit size, and who pays for the additional design services to coordinate that circuit size increase with the rest of the electrical system? To avoid a fight, the specifications should say who bears that responsibility. There is nothing wrong with assigning it to the contractor or vendor who wants to use a product different from the basis of design. Of course, the engineer might also decide that the complications of the electrical change and required electrical design analysis mean Pennsylvania is not equal in this case. General Suggestions The end suction pump and the air cooled chiller are two examples of the situations engineers encounter every day when they evaluate proposed equals. The analysis presented in this article illustrates a thought process engineers can use to help define what is equal and determine whether a proposed product is equal. While engineers generally have broad discretion when determining whether a submitted product is equal, it is important to exercise that discretion fairly and objectively. Here are some suggestions that apply to almost all equipment: Be sure the specifications match the basis of design, and enforce the specs fairly and uniformly. Be clear, Advertisement formerly in this space. AUGUST 2014 ashrae.org ASHRAE JOURNAL 59

6 preferably in the contract documents, about who is responsible for minor or not so minor design or coordination changes (like dimensions of concrete pads) that flow from using an equal. Public contracts typically strongly encourage the engineer to identify multiple suppliers in the name of fostering competition. Common understanding is that if at least three manufacturers are named as suitable, there is no need to include a broad or equal provision. In a tough public bidding environment, specifications might have to be clear that the named manufacturers meet the quality and reputation requirements of the design but the specific product or model proposed must still meet all the functional requirements of the basis of design. Remember the nominal 70 ton (246 kw) chiller example. One solution might be to list the product that is the basis of design and say or equal by B or C to be clear that accepting a different manufacturer does not imply an intent to modify any functional feature or requirement. Read guide specs carefully before incorporating them into a project specification. Verify that the specified features match those in the product data sheet. Remember Red s spec that calls for a stainless steel pump shaft but product data sheet that identifies the shaft material as carbon steel. Specify only those features that are important to the project. Don t flat spec/sole source by the back door don t call for a feature that only one manufacturer can meet and then say or equal. If that special feature is essential to the success of the job, be clear about it. If there is no equal on the market, don t specify or equal. In some cases, such as specialized or custom equipment where there is no equal, negotiating a price that the manufacturer will offer to all bidders could be a way to avoid the appearance of price gouging by a sole supplier. Not every manufacturer s product is suitable for every application. Some products are better suited for certain niches than others. That s part of what product differentiation is all about. Advertisement formerly in this space. 60