R2024-23 Resolution Accepting the Bid and Authorizing the Execution of a Contract with E.L. Pruitt Co., for the Decatur Public Library Chiller Replacement Project

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Page 2 January 31,2024 Project Details: Main components of the library's chilled water system were showing deficiencies or beginning to fail. Some of the failures have led to extensive periods where the chiller was down while waiting for service or parts. Parts to make repairs are becoming obsolete. Additionally,the cooling tower has significant water leaks,and the condenser water pump was leaking. AEX was invited to design a system to remedy these issues and design a system that would give the library a system with reliable performance going forward. The chiller features a modular design,which uses several smaller high-efficiency chiller modules piped in a series;in this design there are six(6). Each module contains two compressors that are stage ON to match the cooling load,therefore twelve(12) stages of cooling. Modular chillers have the lowest energy consumption at partial-load conditions,which is where the system operates for a majority of the cooling season. Modular chillers also offer a high level of redundancy;allowing individual modules to be isolated for service while others remain functional. Multistack was the manufacturer chosen for the library because of their long history in the modular chiller market. Their chillers are designed and manufactured in Sparta,Wl. The existing cooling tower was leaking water and would require substantial labor to replace the failed gaskets. The cooling tower was also not compatible with modular chillers due to dirt/debris that can get into the water and foul the chillers' heat exchangers. The new system will include an Adiabatic Fluid Cooler(AFC),which circulates water in a closed loop. The AFC eliminates the need for costly chemical water treatment and any Legionella outbreak risk that is associated with open cooling towers. The AFC also greatly reduces domestic water consumption. Along with the features mentioned above,the new chilled water system will save utility and maintenance costs. The table below shows the estimated savings anticipated by this system when compared to a standard efficiency system. Component Annual Utility Annual Cost Savings Savings Chiller-Energy 33,000 kWh $3,900 Adiabatic Fluid Cooler(AFC)-Energy 72,800 kWh $8,600 AFC-Water 840,000 gallons $5,300 AFC-Waste Water 330,000 gallons $1,000 AFC-Condenser Loop Chemical Treatment $3,500 AFC—Maintenance $3,700 TOTAL $26,000 The energy savings will be used to apply for energy incentive rebates from Ameren. The current program pays $0.24/kWh saved annually. The estimated incentive from Ameren is$25,000.