Actuators for Chilled Water Valve – These chilled water actuators control the flow rate for a chilled water system in a data center. There are various sequence of operations for chilled water systems and the sequence of operation is usually always different from one chiller plant to another chiller plant. It depends on the components in the loop, the application the chilled water system is supplying cold water for, and what the demand of the system requires for the chiller plant. Some chilled water valves control two-way valves while others control three-way valves. A three-way valve can either be a mixing valve or a diverting valve but the actuators controls the flow in either type of application. Other actuators modulate a valve based on demand. The actuator usually receives its command for position for control from the DDC system or another type of control system. In this case these actuators are controlled by DDC. In the sequence of operation the chiller plant will have a valve line-up usually in a valve matrix that was compiled by the original design engineer and this valve matrix shows the default position of the valves which are controlled by the actuators. Some applications in the piping that are controlled by the actuators include:
Air Management in Hydronic Piping Loops
This is a secondary chilled water pump in a large pump room designated for pumps and piping in a data center. After a few minor tweaks and corrections these pumps all operated flawlessly. There was very little issues with the secondary pump start-ups unlike the primary pumps where cavitation was encountered on the primary chilled water pumps and the condenser water pumps for the chiller. The diagnosis for the cavitation of the primary pumps and the condenser water pumps was that the loops were not properly purged and this caused those pumps to cavitate. The secondary pumps, pictured here, did not have that problem giving kudos to the team that purged the loops on this side of the chilled water system. (more…)
This is a HVAC chilled water system cooling tower fan for a large chilled water system. Four large cooling towers for two chiller plants in a data center. Data center cooling systems generally are redundant not only for emergency situations but also for maintenance. The cooling tower fan typically has vibration switches installed in the fan assembly to shut the fan off in the event of too much vibration. A fan this large (approximately 6 foot diameter) needs to be balanced to prevent vibration that could possibly shake the cooling tower apart and create a safety hazard for workers. The fan is driven by a variable frequency drive that ramps the cooling tower fan up and down depending on demand. (more…)
Large Condenser Pump for a Chilled Water System
This large HVAC condenser pump serves a new chiller located in a data center. This pump pumps condenser water through the condenser chiller barrel and to a cooling to reject the heat absorbed in the chillers evaporator barrel. The pump works to move the water from the chiller to the cooling and then back through the chiller again. The water is diluted with a glycol solution to prevent freezing in the winter time when the chiller needs to run at low ambient temperatures. (more…)
DX CRAC Unit Condensers | Critical Facility HVAC
DX CRAC Unit Condensers | Critical Facility HVAC – Most data centers do not utilize HVAC DX (Direct Expansion) CRAC units or air conditioning but instead use chilled water systems to provide cooling for the data center. In smaller buildings such as remote telecom buildings DX air conditioning systems are used to keep the equipment cool and operating efficiently. A DX CRAC Unit uses vapor compression refrigeration to provide cooling with a chemical refrigerant versus a chilled water system that utilizes chilled water from a chiller. CRAC Units or Computer Room Air Conditioners also serve telecom facilities for telephone services including cellular telephone facilities in remote locations. The CRAC units that serve telecom facilities in remote locations are typically DX CRAC Units that have utility back-up by stand-by generator so that if the utility fails to provide electricity for whatever reason the stand-by generator kicks on and provides power so that the telecom facility can remain on line. (more…)
Chilled Water System Basics
Chilled Water System Basics – Chilled water systems work much the same way as direct expansion systems work except they used chilled water in the coil rather than refrigerant (Technically speaking, water can be classified as a refrigerant). Chilled Water systems can be rather complex and many chilled water systems are found in commercial and industrial applications. There are some chilled water systems used in residential applications. However, chilled water systems in residential HVAC systems are extremely rare. A typical chiller uses the process of refrigeration to chill water in a chiller barrel. This water is pumped through chilled water piping throughout the building where it will pass through a coil. Air is passed over this coil and the heat exchange process takes place. The heat in the air is absorbed into the coils and then into the water. The water is pumped back to the chiller to have the heat removed and make the trip back through the building and the coils all over again.
Trane Chilled Water Systems – Multi-Zone Air Conditioning Systems – This Trane HVAC chiller serves four different apartments. Chilled water systems offer a great way for multi-zone air conditioning. From small apartment buildings to large commercial buildings chilled water systems can serve multi-zone air conditioning systems. From one air conditioning zone to hundred the only limitation is the size of the chiller. If the air conditioning zoning system (the load) is matched up with the right sized chiller (in tons) the system will serve all air conditioning zones and keep all the occupants comfortably cool. Chilled water systems can also be integrated with the boiler system so that the same system can be used for heating and cooling. A good control system will add efficiency and more comfort to the system. (more…)
Plate Heat Exchanger and Free Cooling
Plate Heat Exchanger and Free Cooling – This plate heat exchanger is used in a data center for a chilled water system and is a chilled water economizer. Plate heat exchangers are used in marine applications, industrial processes including chemical processing systems, food processing, and many HVAC applications including chilled water applications, hot water applications, and economizer applications. In chilled water applications plate heat exchangers can be used to bypass the chiller when outdoor ambient temperatures are optimal for using the cooling tower for free cooling. Generally, this free cooling mode can only be used with plate heat exchangers when outdoor ambient air temperatures are below 50 degrees Fahrenheit. When heat exchangers are used for free cooling the control system uses valves to isolate the chiller from the rest of the loop and the heat exchanger is used like a chiller.
Plate Heat Exchanger and Free Cooling continued below…………..