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The Challenge:

The boilers were definitely being shocked. Yearly repair bills for tube damage and failures were already running between $3-5K per week with no end in sight, and fuel costs associated with their combined 76-million BTUs per hour capacity were simply excessive.

This was the persistent situation plaguing the 4 gas-fired boilers – 2-500HP and 2-640HP – at the 2.2 million square foot JCPenney Logistics warehouse in Wauwatosa, WI, the merchandise replenishment hub for the retailer’s upper Midwest retail stores. To accommodate the warehouse’s changing roles over the years, two boilers and six secondary loops zoned with pneumatic controls and 3-way mixing valves were added, along with four additions to the original 1958 building (originally equipped with 2-450HP gas-fired boilers). The pumps had never been changed. In the early 90’s, all of the burners were replaced with higher capacity (HP) models.

Ken Hart, contractor sales engineer for Butters-Fetting, worked with JCPenney’s maintenance crew to identify the problems. He discovered that the system had significant flow issues and was largely out-of- control. “The 6 loops were zoned with 3-way mixing valves and pneumatic controls that were running wild or even wide open. The zones were getting full temperature supply water out-and-back to the AHUs, but the return temperature came back so cold that the temperature differential shocked the boilers. You could actually hear the boilers whine.”

Confident that the problems could be resolved, Hart contacted Industrial Controls to assist with the control issues.

The Solution:

Hart ultimately proposed and installed full, integrated control on the boilers with monitoring to determine what the system was/is actually doing. The new control system he recommended was the Honeywell Light Commercial Building Solution (LCBS) Building and Plant Manager Controllers with digital system control transducers for boiler reset and firing rate

limiting along with pneumatic re-control (using existing valves and actuators). A check valve was also installed to make sure that the flow was going in the right direction in the loops – the pumps didn’t need to be changed out.

The goal of this project was protecting the boilers. The strategy to accomplish this was to limit the output of the supply and return temperature from the boiler to no more than 20, thus eliminating the shock to the plates. Industrial Controls looked at maximizing the total efficiency of the system by allowing the main loop’s supply temperature to determine how many active boilers there would be and each boiler’s ΔT determined how far it fired.

The LCBS digital system controls transducers gave them major system information they’ve never had before, such as temperature control, limiting, valve control, reset and so much more.

According to Hart, “I have lots of confidence with the LCBS. The system works great. It went in easy, programmed easily, and gathered the data needed to make the system perform efficiently.”

Payback on the system was almost immediate. Energy-wise, pre-install/post-install fuel usage comparisons and expenditures were equally dramatic. Total gas costs decreased nearly $130K in spite of significant increases in $/therm and nearly identical heating degree days year-to-year. JCP Logistics now has control of their boilers and in the process has saved money on energy, maintenance costs, replacement parts, and repair costs, while improving employee comfort. And no more shocks!

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