Q&A with Addison HVAC Product Director Peter Fung

Matt Vincent, Data Center Frontier:  Tell us a bit about Addison and United CoolAir (UCA) as solutions providers, in terms of background.

Peter Fung, Addison HVAC: Addison is a premier manufacturer of HVAC products for critical applications. Based in Orlando, Florida, we build complete packaged units that are direct expansion (DX), air cooled or DX water-cooled equipment. We also offer chilled water equipment.

All of our units come complete with factory-installed controls.

Our affiliate organization, United CoolAir (UCA), is located in York, Pennsylvania and manufactures self-contained and vertical units that also provide DX-based as well as chilled water-based cooling for a number of different applications.

DCF: What HVAC equipment and products does Addison/ United CoolAir (UCA) offer for data centers?

PF: Both Addison and UCA offer computer room air conditioners (CRAC) units and computer room air handler (CRAH) units. CRAC units utilize the refrigeration cycle, so a DX-based evaporator coil provides cold air to cool the server/racks. The heat rejection is through a condenser which can be a split remote air cooled or to an integrated water source condenser.

CRAH units utilize a chilled water coil to provide cold air for cooling the server/racks. The chilled water is produced through the data center’s central plant system.

Lastly, CRAC and CRAH units in terms of air discharge, they can be upflow for an overhead ducted configuration or downflow, air discharged, through a raised floor configuration.

DCF:  Are these products available with low GWP A2L refrigerant? What refrigerant are you using? Is product available today with 454B refrigerant?

PF:  Certainly, our equipment is based on refrigerant 410A and we’ll continue to fulfill orders with R410a to the end of this year 2024. That said, we are prepared and ready for compliance with the new A2L refrigerants. We can ship equipment today with R454b, the replacement to 410a, that offers a much lower GWP, global warming potential

DCF: Can you explain how a DOAS, Dedicated Outdoor Air System, is applied in a data center?

PF: Yes, first let me describe the unit. A Dedicated Outdoor Air System is a 100% Outside Air unit, and a subset of a DOAS unit is just basically a high percentage volume of outside air in the mixed air unit. Well, both are being used to introduce conditioned makeup air to provide positive pressurization in the data center. That's the important part: positive pressurization.

Because if we positively pressurize the data center, then we keep infiltration air out. It’s critical to keep infiltration air out of the data center space because that unconditioned infiltration air can impact the data room humidity levels, as well as temperature setpoint control. And loss of humidity and temperature control would negatively impact the proper operation of the server and IT equipment.

The secondary reason for DOAS units is for ventilation purposes. People operating within the data center and operating personnel in non-data center areas too, which is typically administration and office, or technical and engineering departments, and common areas. So certainly, we need to introduce an amount of outside air per code language or ventilation rate procedure.

DCF:  Energy efficiency is an important factor in data center operation. What do you offer for load reduction and efficient operation?

PF:   Addison and United CoolAir equipment is compliant with code language to meet or exceed the minimum efficiency levels As a we apply variable frequency drives (VFD) to compressors for load matching, efficient operation and energy savings. We also select efficient fans and that translates to lower horsepower, as well as using VFD or EC fan motors, to once again offer efficient operation and energy savings.

DCF:  Data centers are mission critical and require redundancy. What back up or redundancy do you offer?

PF:  Very similar to what we just spoke of in terms of efficiency, important components like compressors are offered as a dual configuration and each compressor is piped on an independent refrigeration circuit. So there's redundancy built into the refrigeration system For fans, there are typically multiple fans to offer redundancy. The size of the cabinet and the amount of air that we're delivering will drive how many fans, but we offer customization as well and can design for a specific fan array.  

DCF:  We hear about long lead times in the HVAC industry, how are Addison and UCA managing build cycle and lead times?

We excel at managing attractive lead times. Both Addison and UCA have excellent manufacturing capacity and capabilities, and as a result, our routine build cycle or lead time is typically right around 12 to 14 weeks. That superior build cycle or lead time enables us to solve construction scheduling problems, and it'll enable the job and the end user for an on-time commissioning and opening date.

DCF:  What’s Addison and UCA’s stance on hybrid and liquid cooling?

PF:  Earlier we discussed CRAC and CRAH units applied to data center perimeter-based room cooling and are either DX or chilled water based depending upon the system. They're also available as an upflow configuration for an overhead ducted application as well as a downflow configuration to feed into a raised floor application. Both methods use cooled air distributed to the room to cool server/racks.

However, what we see today are more powerful servers as well as a high density of servers in a rack. What that means is more heat being given off and that heat has got to be removed so that the servers can continue to run efficiently and process data. And so now we're stretching the boundaries of efficient cooling through traditional CRAC and CRAH units providing room cooling

A solution is liquid cooling through a CDU, or cooling distribution unit. Water is much more efficient than air in removing heat for these increased power loads in racks today. The CDU includes a water-to-water heat exchanger and takes water on the primary side of the heat exchanger to cool and condition technology cooling system water, or our load water, that is then delivered to the server rack for cooling. To ensure water is delivered we include a redundant N+1 pump package that is fully piped and capable of being manifolded and connected to additional units for scalability and increased loads.

A CDU utilizing water is more efficient than air to accept that heat rejection, dissipate that heat and allow the server/racks to operate more effectively and operate more efficiently.

Our goal at Addison and United Cool Air is to provide our customers with cooling solutions that are effective, efficient and sustainable. Sustainability is important because we are protecting the planet too.

What we also strive to do is provide differentiated products through innovation and customization. We're in a fast-paced world, so with that customization, we need quick design and development. Quality and service is at the top of the list for both Addison and UCA. Quality and service builds a trusted partnership with our client base.