The Essential Multistack® Chiller Cleaning Guide

The Essential Multistack® Chiller Cleaning Guide

Multistack® modular chillers comprise a series of separate chilling units that operate collaboratively to deliver large cooling capacity in a small footprint.

Multistack® chillers are well-designed, rugged, and ultra-reliable. However, even the most robust chiller systems can suffer from hard water scaling buildup, which can cause significant efficiency loss and operational issues.

What is a Multistack® Chiller?

Multistack® pioneered compact chilling systems, which combine multiple modular chillers to make a complete and expandable cooling system.

These modular chillers come in several capacities and allow facilities to use just enough energy to meet operational demand. Modules can be mixed, matched, and combined to create up to 15 modular arrays and 1,275 tons of cooling capacity.

Multistack® chillers offer:

• Effortless expandability: A modular design lets companies scale systems as needed.
• Affordable redundancy: Redundancy in conventional chillers requires adding a second chiller of equal capacity or three chillers at 50% capacity. The Multistack® modular design achieves the same redundancy with one backup module, delivering needed redundancy at a fraction of the cost.
• Easy installation: A modular design allows facilities the flexibility to build chillers module by module. A space-efficient Multistack® module provides up to 70 tons of cooling capacity in a 9-square-feet footprint.
• Minimal maintenance: Easy and economical to service. No oil changes or eddy current analysis is required. Just keep the water clean and treated.
• Low charge: Compliance with ASHRAE 15 and CSA B52 standards eliminates auxiliary ventilation, monitoring, and SCBA equipment, which saves money and installation time, and meets LEED certification requirements.

Importance of Maintenance/Chiller Cleaning

Preventative maintenance is key to maintaining efficient operations with Multistack® modular chillers, which utilize brazed plate heat exchangers to transfer energy (heat) with high efficiency or minimal thermal loss. When operating with hard water or at elevated temperatures, scale deposits from minerals within the water can fall out of suspension and plate onto heat transfer surfaces.

These deposits:

• Increase pressure drops,
• Insulate the heat transfer surface, and
• Cause pumps to work harder to pump chilled water.

Over time, these deposits decrease heat exchanger efficiency and can act as a breeding ground for particulate fouling and corrosion.

Step-by-Step Guide to Multistack® Chiller Cleaning

Before descaling brazed plate exchanges, visit the Goodway Technologies calculation tool at www.goodway.com/Multistack®-calculator. This calculation tool determines how much ScaleBreak® MP to use and the circulation times for proper cleaning.

Follow these steps to perform cleaning:

1. Close supply and return valves to isolate the brazed plate heat exchanger.
2. Unbolt couplings and remove the 90-degree bend from both the top and bottom of the BPHE.
3. Position a GDS MSA adapter on both the low and high point of the brazed plate heat exchanger. These fittings will be the entry/exit point for ScaleBreak MP cleaner and can be closed to isolate the brazed plate if necessary.
4. Attach circulation hoses to pump fluid into the bottom of the brazed plate heat exchanger and return fluid out of the top.
5. Fill the exchanger with water and perform a hydrostatic test by turning on the pump and circulating water.
6. Bleed off water equal to the volume of ScaleBreak MP used. If too much water is removed, add some back in to complete the circulation loop.
7. Water-formed deposits occupy volume. As a result, technicians may need to add water during the cleaning process as deposits dissolve.
8. Circulate ScaleBreak MP solution for the recommended time determined by the calculator.
9. Make sure solution remains active by following the “Testing ScaleBreak’s Effectiveness” procedure.
10. Begin flushing after ScaleBreak MP has finished working.
11. Flush the heat exchanger by turning off its circulation pump. Remove the return hose from the recirculation system and put it in a drain.
12. Add a fresh water hose to the recirculation bucket on the pump system and turn the pump back on.
13. Continue running clean water through the heat exchanger for 10 minutes or until return water runs clear.
14. Disconnect the hoses and remove the GDS MSA adapters. Reinstall the original fittings and turn the supply water back on. Check fittings for leaks and tighten couplings if needed.
15. Return the Multistack® chiller to service.

Click HERE for a more detailed downloadable description of the cleaning process.

How has Goodway Partnered with Multistack®?

Goodway Technologies partnered with Multistack® LLC in 2019 to offer customers a safe cleaning solution to ensure heat transfer and efficiencies remain optimal in modular systems.

Through this partnership, Goodway Technologies offers ScaleBreak® MP for Multistack® modular chillers. The unique blend of citric acid with corrosion inhibitors and wetting and penetrating agents delivers excellent and efficient cleaning without comprising the integrity of equipment base metals. The biodegradable descaling solution safely dissolves scale deposits into a liquid suspension, allowing technicians to flush scale out of the chiller without leaving residual solution behind.

Goodway offers a simple-to-use calculator to help facility managers calculate the correct amount of ScaleBreak® MP to use when cleaning Multistack® chillers. This allows for less wasted money and product.

Goodway has also created GDS-MSA adapters to simplify your Multistack cleaning experience.  These grooved type adaptors come in 1-1/2”, 2”, 2-1/2”, 3” & 4” and can be used in conjunction with our GDS clean-in-place pump systems for a quick, effective cleaning process.

Case Study

Goodway has had positive results with its specially designed solution. Heavy scaling had led to inefficient performance at a facility with three, nearly 20-year-old Multistack® 85-ton modular chillers.

After circulating Goodway ScaleBreak® MP through the brazed plate condensers, head pressure dropped from 423 PSI to 254 PSI and the Energy Efficiency Ratio increased from 8.6 to 15.7. The company estimates the efficiency savings at $116 per day or $42,340 annually. The solution also kept the equipment operating, eliminating the need to replace heat exchangers.

Next Steps

Using Multistack® modular chillers offers significant benefits for industrial cooling solutions. But even the best designed systems can suffer from hard water scale buildup. Goodway Technologies has partnered with Multistack® LLC to develop an efficient and effective way to clean water scale buildup from these vital systems. Access information on ScaleBreak MP Liquid Descaler designed for Multistack® chiller cleaning. Determine the amount of ScaleBreak MP needed with the Multistack® Chiller Descaling Calculator. If you need more assistance, Goodway Sales Engineers are always available to help you identify the best maintenance solutions for Multistack® chillers to keep these critical units operating at peak efficiency.