McQuay RPE User Manual

Chemical-Free Water Treatment

For Daikin McQuay Evaporative Condenser Rooftop Systems

Daikin McQuay evaporative condenser rooftop systems can provide as much as 44% in compressor energy savings compared to competitive air-cooled rooftop units. Until recently, chemical water treatment was required to prevent scale build-up and microbial growth in the moisture-laden condenser section of these units. Daikin McQuay offers an alternative chemical-free water treatment system that can substantially lower the cost of water treatment, eliminate the use of hazardous chemicals and simplify the water treatment process.

Benefits

• Eliminates chemical costs. This system eliminates the use of hazardous chemicals, including scale inhibitors, biocides and corrosion inhibitors. Typical yearly savings range from $1,800 to $2,700 per year for a 150 ton evaporative condenser rooftop unit.*

• Reduces water consumption costs. With this system, supply water typically can be cycled through the evaporative system six times before it must be drained off to prevent scale. With chemical treatment systems, only three to four cycles are possible. This represents a water consumption savings of about 10%.*

• Reduces sanitary sewer costs. Savings in sanitary sewer costs can be even more dramatic. That’s because this system requires no sanitary sewer usage—all condenser water, including blow-down, usually can be drained to the storm sewer or used for irrigation (check local codes). This represents a 10 to 15% water cost savings if sewer ow is measured (i.e., credit is given for the water that evaporates during the cooling process) and even more if it is not.*

• Eliminates hazardous waste concerns. Because hazardous chemicals are eliminated, so are OSHA and EPA requirements and oversights associated with their use in your facility.

• Minimizes corrosion. Daikin McQuay uses only stainless steel, copper and PVC in its evaporative condenser plumbing. Clean, chemical-free water, saturated with precipitates by this system, does not attack these materials.

• Improves system performance. Low total bacteria count (TBC), cleaner water and virtually no biolm with this system result in more efcient heat transfer and better system performance.

• Factory Package: Daikin McQuay factory-installs and commissions the entire chemical-free water treatment package. Commissioning includes a water sample to provide optimum control and make blow-down adjustments, and several, periodic conductivity and TBC tests to check for proper operation.

Engineered for flexibility and performance

™

Chemical-Free Water Treatment

How It Works

As a scale inhibitor, the Daikin McQuay chemical-free system uses pulsed electro magnetic elds to neutralize the charge on particles suspended in water, causing them to attract to each other rather than to form scale on plumbing and heat transfer surfaces. The particles grow, encapsulate any microorganisms, and precipitate out of solution as a powder. A cyclone separator removes the powder from the system during the blow-down process.

For microbial control, the system uses pulsed electromagnetic elds to attack the cell walls of any microorganisms that are not encapsulated. As a result, TBC is typically 75% less than with chemical treatment systems. In fact, TBC is so low that biolms are normally prevented.

Easy Maintenance

The Daikin McQuay chemical-free water treatment system has no moving parts and is easy to maintain. Inspection and monitoring are only required once or twice per quarter, as follows:

• Check the water conductivity (and clean conductivity sensor if necessary).

• Check total bacteria count (TBC).

• Inspect general operation and controller settings.

A Cleaner Environment

Daikin McQuay evaporative condenser rooftop units equipped with a chemical-free water treatment system contribute to a cleaner environment by reducing energy usage and by eliminating the introduction of hazardous chemicals into the waste stream.

LEED® Point Available

Chemical-free water treatment systems qualify for a LEED point under the “Innovation” heading, per a Credit Interpretation Request posted on the USGBC website.

12 To 18 Month Payback

The superior performance of the Daikin McQuay chemicalfree system costs a little more up front than a chemical feed system, tanks and pumps. However, the water and chemical savings generally provide a 12-18 month payback in addition to the nancial benet of cleaner water and heat transfer surfaces.

Table 1 shows typical yearly water treatment cost savings when using this system on a Daikin McQuay 150-ton evaporative condenser rooftop unit.

Table 1: Typical yearly treatment cost savings with Daikin McQuay Chemical-Free Water Treatment*

Los Angeles New York City

Typical Chemical Treatment System

Water Cost $1,067 $628

Chemical Cost $2,000 $2,000

Total $3,067 $2,628

Daikin McQuay Chemical-Free Treatment System

Water Cost $923 $539

Chemical Cost $0 $0

Total $923 $539

Chemical-Free Savings $2,144 $2,089

Percent Savings 70% 79%

While there are water treatment costs associated with evaporative condensers, they are typically small compared to the total energy savings provided by a Daikin McQuay Evaporative Condenser unit. (See Table 2).

Table 2: Typical yearly total cost savings with a Daikin McQuay 150-ton RPE Evaporative Condenser Rooftop Unit*

Los Angeles New York City

Competitive Air-Cooled Unit

Energy Cost $30,200 $17,860

Water Treatment $0 $0

Total $30,200 $17,860

Daikin McQuay Chemical-Free Treatment System

Energy Cost $22,100 $12,375

Water Treatment $923 $539

Total $23,023 $12,914

RPE Cost Savings $7,177 $4,946

Percent Savings 24% 28%

History

Over 1200 chemical-free water treatment systems using this same design are currently in use on cooling towers and evaporative condensers in the United States. Daikin McQuay can provide you with a list of satised, repeat customers.

Contact your local Daikin McQuay sales representative for more information on how your building environment can benet from innovative Daikin McQuay rooftop systems, or visit www.DaikinMcQuay.com.

* All energy analysis and comparison charts provided in this document are

estimates and have been generated using Daikin McQuay Energy Analyzer™ software. Actual customer results may vary. For access to Energy Analyzer software, contact your local Daikin McQuay sales representative.