Commonly Used Terms:

Refrigeration: This is the circuit and components associated with the compressor, expansion valves, heat exchangers, condenser, and receiver. There is just one refrigeration circuit per unit in the Mydax designs.

Proportional Control: Conventional methods are to cycle the cooling power between full-on and full-off as cooling needs mandate; these harsh load changes can cause excessive wear of the refrigeration components, resulting in relatively short service intervals. Mydax's unique and patented approach provides precise proportional control using a modulation technique to keep the refrigeration circuit balanced. This is our most important feature, resulting in the high reliability and precise stability of our products. By its design, our proportional control algorithm also supplies a more stable operating system for our temperature control mechanisms. It is through these means that Mydax has been able to build units with a temperature stability as low as ± 0.02°C.

How is the capacity of my chiller rated?

Chillers, air conditioners, and heaters are often rated in BTU/hr. This is a power specification that refers to the amount of energy used in a period of time. On large air conditioning system with high BTU/hr ratings, it is easier to refer to the power in "tons". Heat is often specified in kilowatts (kW)

1 ton is the same as 12,000 BTU/hr -- so 25 tons is the same as 300,000 BTU/hr. 1 kW is the same as 3415.2 BTU/hr.

How do I determine the capacity of my cooling and heating requirements?

This is determined by the amount of energy that must be exchanged from the source. When specifying capacity, we have to be sure to compensate for the heat generated by the unit itself. Without careful design, this oversight can result in an under powered and less useful product.

When specifying cooling requirements, realize that plain water freezes and alternate fluids or mixtures must be used in order to avoid icing up the heat exchangers. Also, special design techniques must be used to achieve temperatures below -35°C; this adds quickly to the cost of a unit.

Yes. Mydax's patented control techniques provide for seamless transitions between cooling to heating. Our Chiller/Heater combination units are specified with high precision over a wide temperature range. With the proper selection of the recirculation fluid, a single fluid can likely cover your entire range.

Often a system is required to go to an extreme temperature; however, it may not matter that it gets there very quickly. In this case, a cooling capacity can be specified at a more conservative level, allowing for a lower power unit which may take up less space, less energy, and would be less costly.

How can Mydax achieve such accurate temperature stability, and how does that help me?

All of Mydax's units are microprocessor controlled. This allows proportional control of the cooling and heating systems. For example, proportional control is what happens when you drive a car and press on the accelerator harder or softer depending on your desired speed. With this method, a smooth and accurate speed can be achieved. Non-proportional control systems operate similar to turning on and off the engine to control the desired speed.

Many chiller and air conditioner applications don't require much stability or don’t have the budget to afford a tightly controlled system. Those applications are better filled with a more conventional chiller vendor. Mydax prides itself on the capability to set and hold a temperature within one-tenth (0.1) of one degree and even as low as within two-hundredths (0.02) of a degree. Our standard chiller design is to maintain no more than a 0.5 degrees from set point.

I have both limited space and budget, is it possible to control more than one fluid temperature with one chiller?

Because of the high precision and customization that Mydax is capable of, our chillers are likely to be more expensive than the run-of-the-mill chillers. Mydax's unique design allows for having one unit with 1, 2 or 3 independently controlled output loops (or channels). Using this method, a much lower "per-channel" cost can be achieved. Each channel can be set to its own independent temperature so there is no loss in functionality, and this also allows us to fit more in the same footprint.

Why are there so many choices for the types of fluid to be used in my chiller application?

Well first, plain water is good for many applications in the medium temperature range, its easy to get a hold of; and for slightly extended temperature ranges, you'd mix in either a glycol or an alcohol. However, there are many reasons not to use water:

• Limited temperature range (+10°C to +90°C)
• Ions in the water can cause corrosion and result in a build-up of residue
• Water nurtures organic material growth

For these reasons, other fluids are used. If the temperature range is not a limiting factor, deionized water and DI filters can be used to control water clarity, conductivity, and corrosiveness.

For extended temperature ranges, we could use the following:

This is not a complete list, but it gives you an idea of the different options we have.

This is usually mandated by the apparatus that is hooked up to the chiller and is specified in gallons-per-minute (GPM). You want to have enough flow to transfer heat to or from your application at the desired rate.

As you will see in the next question, the pressure determines the type of pump we use. It is also imperative to select the proper size of pump; all pumps are specified with a GPM at some PSI. A one-quarter horsepower pump might be able to put out 10 GPM but not with any pressure. Likewise, a similar sized pump may be able to build up plenty of pressure, yet at a very small flow rate. This is the same as specifying both voltage and current requirements for an electrical appliance.

We will generally determine this for you -- unless you have some specific requirements. When we choose pumps for your system, there is always a trade-off between higher flow rates and higher pressures.

Centrifugal pumps are good for high flow rates at low pressures. Turbine pumps are used for higher pressure and low flow rates applications. Positive Displacement pumps are used where a constant flow is required over a wide range of pressures. Magnetic Drive pumps and Can pumps have no seals to leak, so they are great when leaks would cause a disastrous condition; but, are quite costly.

This is determined by the fluid and temperature range. We want to be sure that we choose plumbing that is compatible with the fluid to avoid deterioration of the pipes or contamination of the fluid. For example, in a DI water system, we would use plastic pipe or stainless-steel; and, for high temperature requirements, copper pipe or teflon tubing would be used in place of the lower temperature rated plastics. Sometimes our customers will require stainless-steel for their application because of the products that it comes in contact with or mere fact that it looks cleaner than copper pipe or PVC.

All refrigeration systems do nothing more than transfer heat energy from one place to another. That's why there is heat coming out from around your home refrigerator -- it is simply taking heat energy from the inside of the refrigerator and freezer box and dumping it into your kitchen. Air-cooled chillers are often either placed outside or vented to the outside through some duct work.

Although air-cooled heat-exchangers are more common in our daily life, a water-cooled chiller provides a much more efficient heat transfer. The size of the water-cooled chiller's compressor and other components can be significantly smaller and less expensive to operate. A water-cooled unit uses facilities water (i.e. city water supply or well water) to remove the heat energy. Where plentiful, this is often a one-way trip for the water: cool water coming from the supply and warm water going straight to the drain or sewer. In other cases the water may be recirculated to a large outdoor chiller that sends the heat off into the air.

Mydax is experienced in outfitting our chillers for outdoor operation; this requires weather-tight panels for the electrical and electronic components. Weather-tight connectors are used for all electrical interconnects exposed to the elements. Our standard powder-coated steel frames are suitable for most outdoor applications.

Yes, definitely. Although Mydax builds most small and medium sized units for use on 208/240VAC single and three-phase power, larger units require 480VAC in order to supply their necessary power.

Most compressors are not available for 110/120VAC because of the relatively high power requirements -- they would need a dedicated electrical circuit regardless.

The Mydax chillers achieve their efficiency and accuracy specifications with the use of an integrated microprocessor to manage the chiller's proportional control system. Each system is designed for the customer by choosing the best pumps, compressors and control subsystems to meet their requirements.

Many features come standard with a Mydax chiller, including the microprocessor-based controller with LCD display, data-entry keypad, and RS-232 interface. Those items that we feel are more sensitive to custom design are quoted as options, such as:

• Fluid Flow Meter
• Fluid Pressure Meter
• Particle Filter
• Deionized Water Compatible
• Deionizing Filter
• Deionizing Fluid Monitor
• Analog Interface (RS-232 is standard)
• Remote Start/Stop Capability
• Windows™ (TM) 98/NT Remote-Control/Logging Software

Please indicate, on the Chiller Quote Request Form, any items you are interested in.

Yes, for a nominal fee, we will train your on-site support team to perform periodic maintenance and simple repairs such as pump replacements.

Mydax units are inherently reliable and require very little support once installed at the customer's site. Mydax offers many Service Options for our chillers, from World Wide, On-Site service to extensive documentation and troubleshooting on our web site. Mydax also offers cutting edge service with VSOS™ Virtual Service On-Site. With VSOS, remote monitoring, via modem, of a Mydax system is possible on any PC.

Mydax will be a competitive, cost effective solution for applications demanding any of the following:

• High Quality
• High Precision Stability
• OEM Supplier
• Custom Design
• Special Fluid types, flows or pressure
• Reduced Cost with multiple loops on same compressor
• 3,000 to 300,000 BTU/hrs (from 1kW up to 25 ton)
• Computer Controlled

On our web-site is a Chiller Quote Request Form, please fill it out as best as you can -- this will speed up the process. We will be in contact with you, either by email or phone, within one business day to discuss any further questions. Quotes generally take a few days once we get the details ironed out; we have to work out the design and specifications, then price the major components. We can either email a rough price estimate or provide a professional quotation via fax or mail, as you wish.