Compressor Rebuild – This freshly rebuilt reciprocating compressor is destined for a large commercial chiller. Chillers chill water for air conditioning. Compressors compress refrigerant vapor and pump the compressed refrigerant to the condenser to be condensed into a liquid. The compressor provides compression which is an integral part of the refrigeration process. The old compressor was condemned for electrical burn out. The windings in the old one burned up and caused the circuit breaker to trip. (more…)
HVAC Centrifugal Compressors – Centrifugal compressors are used in many applications including pipeline transport of natural gas along with many other related applications including vapor compression refrigeration. These compressors have different operating limitations than the reciprocating compressor, the scroll compressor, and the rotary compressor. They an operating range where it operates efficiently however outside of this range, either the over or under that operating range, is basically useless. Other issues make them not ideal for use in certain applications because of the operating range issues. (more…)
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:
About Chilled Water Systems | HVAC Hydronics
About Chilled Water Systems –
Chilled water systems are mainly used in large commercial HVAC air conditioning systems and industrial cooling applications although there are some residential and light commercial HVAC chilled water systems in use. Chilled water systems are popular because they use water as a refrigerant. Water is far less expensive than refrigerant. This makes them cost effective especially in commercial HVAC air conditioning applications. Instead of running refrigerant lines over a large area of the building water pipes are ran throughout the building and to evaporator coils in air handlers for HVAC air conditioning systems. The chilled water is pumped through these pipes from a chiller where the evaporator coil absorbs heat and returns it to the chiller to reject the heat.
Chilled Water Pipe Vibration Isolators
Chilled Water Pipe Vibration Isolators – Vibration isolators protect the chilled water piping from receiving vibrations transmitted through the piping when the chillers are running. The vibrations can create problems not only for the chilled water piping but also for the buildings structure. The vibration isolators reduce or eliminate the vibrations that can be transmitted by the chillers. Other equipment normally specified with vibration isolators includes air handlers, pumps, condensing units, generators and most types of equipment with motors. Not only are vibration isolators required in the piping but vibration elimination springs or spring isolators are required are required on chillers, pumps, air handlers, and the other types of equipment named above which can produce vibrations when running. Vibration isolators are usually rated according to the static deflection the vibration isolator provides for the equipment. HVAC piping whether it is for hot water or chilled water usually is also specified with springs in the pipe hangers to avoid further issues that can be caused by vibration. Depending on the location vibration isolators will also be rated for seismic activity with further specifications calling for seismic restraints on the equipment and associated piping. (more…)
Crankcase Heaters and Compressors
Hello, I have a question about crankcase heaters, I am aware that they are for the purpose of keeping the refrigerant from being saturated in the compressor when not running, but if the refrigerant is R-22, and it becomes saturated at approx.
40 degrees, & the a/c unit is only operating during warm ambient temps., when it is off for the evening hours & the ambient temps stay above 40 degrees, why would one need to have a crankcase heater on during this temp. range, or are crankcase heaters designed to be activated only during the colder months? Also if one installs unregulated crank case heaters (always operating), can this be a negative factor for the compressor life?
DDC Controlled Chilled Water Actuator | HVAC Automation
This chilled water actuator is attached to a valve which supplies chilled water to the air handling unit chilled water coil. The actuator modulates the valve based on a set point inside the DDC program. If the program has trim and respond capabilities the set point will rise up and down based on demand from the VAV boxes or the HVAC zones. Most DDC controlled actuators work off of a DC volt or current signal. The common chilled water actuator motor is generally powered by 24 volts AC. The actuator has the ability to modulate by the DC signal. If the chilled water actuator is a 0 to 10 volt actuator a zero volt DC signal the actuator would be closed if it is a normally closed valve* (*depending if the actuator is normally closed or normally open). If the chilled water actuator gets a 5 volt signal then the actuator will move the valve to a fifty percent position. Therefore, if the chilled water actuator got a 10 volt DC signal it would open 100 percent if it is a normally closed valve. Other actuators work off of a milliamp signal. 0 to 20 milliamps or 4 to 20 milliamps are the usual milliamps signals that will modulate the valve. Other voltage ranges for mudulating an actuator are 2 to 10 volts DC and 0 to 5 volts DC. (more…)
HVAC 3R NEMA Rated Control Panels
HVAC 3R NEMA Rated Control Panels – These control panels offer resistance to inclement weather. They house the DDC controllers for two small chillers and two air handlers. The chillers provide chilled water for air conditioning to the air handlers. The controllers offer energy management for the air conditioning system. The controllers were mounted outside for a few reasons. The main reason was because this location was closest to the HVAC equipment which provides air conditioning to the building. The secondary reason was because there was no safe or ideal location to install these panels inside the building. (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…)
Old McQuay Chiller Control Panel
This panel is part of the controls for an older McQuay chiller. New chillers whether they be McQuay, Trane, York, or Carrier chillers still require these types of controls in them to make them work. This part of this electro-mechanical control panel consists of contactors and switches (both manual and automatic) for electro-mechanical control of this chiller. To the right is the main power which feeds the unit with three phase main power. This power is first fed into a manual disconnect switch so that power can be secured to the unit if maintenance or repair is necessary. from there, the power is split between three separate loads. The first load the main power supplies is the compressors. Before the main three phase power arrives at the compressor contactors it goes through additional manual switches so the the compressor circuits can be isolated if necessary. The compressors have overload protection built into the compressors. The second load to which main three phase power serves is the fan contactors. (more…)