VAV Air Handler and HVAC Zoning
Filed under: Air Conditioning, Air Handlers, Chilled Water Systems, Commercial HVAC, HVAC Fans, HVAC Photos
VAV Air Handler
VAV Air Handlers are ideal for providing zones in a commercial building. Office space typically has several offices and open areas that need to be conditioned for the comfort of the people working in those areas or offices. By installing VAV boxes and zoning the duct work from those VAV boxes these areas and offices can be kept comfortable using a VAV air handler system. Each box can have its own thermostat and that area or office served by that particular VAV box can be maintained and conditioned for the people working in that space. The VAV box will receive its conditioned air from a VAV air handler through a primary duct that feeds air to the VAV box. The VAV box then determines the amount of air to the secondary duct by a damper located in the VAV box. Depending on what the thermostat temperature set point is and the temperature in the space will determine the amount of air flow the space will receive from the VAV box. Additionally, A VAV box with reheat will energize the heat strips or open the actuator for the hot water coil if the set point and room temperatures calls for the reheat to provide heat to the space (If the VAV box is equipped with reheat). Read more
Portable Load Bank for UPS Testing
Filed under: Data Centers, Electrical Systems, Emergency Power
Portable Load Bank for UPS Testing
This is a portable load bank used for testing small UPS (Universal Power Supply) systems and for other electrical loads. New UPS systems are tested to ensure they operate properly and can hold the designed load whenever a power failure occurs. It is a way to test the UPS system without hooking up an actual load to the system with the actual load being the computer systems the UPS will power in the event of a power failure. This testing ensures the UPS equipment will functionally operate after the intended load is hooked up to the UPS system. Included in the test is a time factor on how long the batteries will power the load without utility or a back-up generator. It answers the question of how long one has to shutdown their computers before the batteries are drained and the UPS becomes inoperable for lack of power. Typically most owners will specify a time requirement for how long they want the batteries to power the designed load before they must shutdown their computers. Depending on how much time cushion the owner wants for this purpose will depend on the design of the UPS and how many batteries needed to power the load temporarily. This test with a load bank determine that time. What happens if the utility service goes down and the generator fails to start. How much time do you have to before you will completely lose power back-up from the UPS batteries? Read more
Domestic Hot Water Mixing Valve and Domestic Storage Tank
Filed under: Boilers, Commercial HVAC, HVAC Piping, Heating, Hot Water Systems, Residential HVAC
Domestic Hot Water Mixing Valve
This domestic hot water mixing valve offers a way to temper the hot water coming from a hot water loop and boiler. It is very important to maintain the appropriate and desirable temperatures of water used for domestic water use. First you want to maintain a safe temperature so people are scolded by extremely hot water temperatures. Hot water boiler loops generally work on a temperature of 180 degrees Fahrenheit and this temperature is too hot for human contact without scolding or seriously burning the skin. A mixing valve is used in the loop to maintain a safe temperature for human comfort. The hot water is mixed with cold water at the mixing valve and the result is the temperature dialed into the mixing control valve which has a range of 120 degrees to 140 degrees if used for domestic hot water applications. Other mixing valves can be purchased that will give a whole range of temperatures including mixing valves that can be controlled by PLCs or DDC to maintain specific temperature ranges for whatever the desired temperature is for the application. Read more
Water Tower Pumps and Controls
Filed under: Commercial HVAC, HVAC Photos, HVAC Piping
Water Tower
Water towers maintain a ready limited supply of water for communities in the event the water main goes down. Many water towers are used for emergency situations for the fire department to have water for fighting fires and for water fire suppression systems to have a supply of water for the emergency if it should arise. Read more
Cooling Tower Evaporation Cools Water
Filed under: Air Conditioning, Air Handlers, Chilled Water Systems, Commercial HVAC, Data Centers, Electrical Systems, HVAC Fans, HVAC Photos, HVAC Piping
Cooling Tower Evaporation Cools Water
Cooling towers use the process of evaporation to cool or removes heat from the condenser water that was transferred to the water in the chiller condenser barrel. The heat is absorbed at the load in this case in a data center on a data center floor. The servers and electrical equipment produce a massive amount of sensible heat. The heat is absorbed by computer room air conditioners or computer room air handlers. These systems, computer room air handlers and air conditioners, have chilled water coils. The chilled water originates at the chiller into the primary loop. The water circulates through the primary loop and makes its way into the secondary loops of the chilled water loop. The chilled water flows through the secondary chilled water loop and to the loads or the coils in the computer room air conditioners and/or computer room air handlers. The heat is absorbed into the chilled water and is carried back to the chiller where the evaporator absorbs the heat from the chilled water. Read more
Generators Serving a small Data Center
Filed under: Commercial HVAC, Data Centers, Electrical Systems, Emergency Power
Generators Serving a small Data Center
These generators serve a small data center giving the data center back-up emergency power in the event of a loss of utility. Most data centers have redundant power from the utility and back-up generators. In other words, the utility will provide two sources of utility power from two different power stations or sub-stations so if one source station loses power for whatever reason the system automatically transfers to the back-up source of power or the other power or sub station. The transfer typically takes place through large switch gear systems that will switch from one source to the other source. Automatic transfer switches will offer a delayed transfer so there will be a small amount of time when there will not be any main power supply when the transfer takes place from one utility to the other utility. This where UPS systems fill in the temporary loss of power from one utility to another or from utility to generator power. A data center equipped with a static transfer switch (as opposed to an automatic transfer switch) will not have a temporary loss in power from utility to utility. The static transfer switch has a switchover time in microseconds so the transition is very fast. So fast that a computer cannot read the loss in power so the core load – the computers in the data center – never even blink and keep on working almost as if nothing happened without the UPS back system. Read more
Air Management in Hot Water and Chilled Water Piping Loops
Filed under: Air Conditioning, Boilers, Chilled Water Systems, Commercial HVAC, HVAC Photos, HVAC Piping, Heating, Hot Water Systems
Secondary Chilled Water Pump Room
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 of air 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. Read more
Air Handler Smoke Detectors and the NFPA
Filed under: Air Conditioning, Air Handlers, Commercial HVAC, HVAC Fans, HVAC Photos, Heating
Air Handler Smoke Detector
Installing duct smoke detectors or smoke detectors in air handlers are not ideal for protection of life and property in the event of a fire or smoke condition. The NFPA and mechanical codes cover smoke detectors. It is preferred that the occupied and non-occupied areas and spaces have smoke detectors simply because the fans in air handlers or that move air through duct work may not be operational at all times so having smoke detectors in the duct work will not offer the amount of protection that smoke detectors would offer in the spaces or area served whether those areas or spaces are occupied or not. Yes, if the fan is operational it would create a negative at the return and suck the smoke into the duct work where a smoke detector would trip and alarm people there was smoke in the building somewhere but ideally in most circumstances it is better to have smoke detectors in the spaces and areas of the building for better protection. Smoke detectors are ideal for detecting a problem with the air handler. For example, if the fan motor were to begin smoking the duct detector would, ideally, shut down the system before the fan caught on fire. Furthermore, the NFPA specifically states that detectors installed in the air duct system shall not be used as a substitute for open air protection. So, now that we know the NFPA states smoke detectors in the duct work are no substitute for open air smoke detectors protection is there a requirement for smoke detectors in the duct work? Read more
Rooftop Air Handler with Integral Heat Recovery
Filed under: Air Conditioning, Air Handlers, Chilled Water Systems, Commercial HVAC, HVAC Fans, HVAC Photos, Heating
Rooftop Air Handler with Heat Recovery
This large rooftop air handling unit also has a heat recovery wheel integrated inside the air handling unit itself. The all in one air handler and heat recovery unit saves energy by recovering heat that would otherwise be vented outside in the winter time and in the summer removing heat from the air that is used for economizer and minimum outside air. In the winter the outside air dampers will open to bring fresh air into the building and vent stale air out of the building. The air inside the building contains heat. As the air is passing through the duct to be vented outside it encounters a heat recovery wheel. The air hits the heat recovery wheel and keeps moving past the heat recovery wheel but it leaves some of the heat it contained in the heat recovery wheel. The wheel is turning and this heat contained in this wheel (from the old stale air) turns to the duct where the fresh outside air is entering the building. This cold air hits the wheel and absorbs some of the heat that was left there by thew old exhaust air that was vented outside. This saves energy by capturing waste heat in air that is vented outside and exchanging it to the air coming inside via the heat recovery wheel. Read more
A Hot Water Unit Heater Protecting a Mechanical Room
Filed under: Boilers, Commercial HVAC, Electrical Systems, Gas Furnaces, HVAC Fans, HVAC Photos, HVAC Piping, Heating, Hot Water Systems, Thermostats
A Hot Water Unit Heater Protecting a Mechanical Room
Unit heaters are used in various places to protect equipment and provide comfort to occupants. This hot water unit heater provides protection for a mechanical room where there is a large air handler and other associated equipment in the mechanical room. This hot water unit is controlled by DDC. A thermostat on the wall detects the temperature of the mechanical room. The DDC system will maintain a temperature set point by energizing the hot water unit heater fan and modulating the hot water valve open on the hot water piping. The actuator and hot water valve can be seen in this photo on the right lower half of the hot water unit heater. The valve is a two position valve so it is either open or closed with no modulating the valve on the unit heater. Read more
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