Tag Archives: cold air

Proper Humidity Levels and Factors for Home Comfort & Health | HVAC Health

moist and dry air problems & health

Proper Humidity Levels and Factors for Home Comfort & Health - The Contents and Make Up of Air and Humidity

Proper Levels of humidity Factors for Home Comfort and HealthProper Humidity Levels and Factors for Home - Humidity is important to our home and health and it is important to maintain the correct humidity in our homes and workplaces for our health. What is humidity? Humidity is simply little water droplets in the air. Cold air is nearly saturated with these little water droplets because the contents of cold air allow the air to hold more water droplets or humidity. As air is heated it expands and holds less humidity. When you heat the air in your home using a furnace, boiler, or heat pump this air expands and becomes drier. It is air with less humidity relatively speaking before it was heated and compared to the outside air. Air that is 30° F with 80% humidity will only be 15% humidity at 75° F. That is a big difference in humidity levels in the home after the air is heated. Granted, you are not heating air from 30° F to 75° F with your furnace. Depending on the set up of your thermostat and heating system you are most likely heating air that is 68° F to around 70° F to 75° F depending on the thermostat setting. The point is unless you have a source providing humidity to the air stream you are simply reheating dry air from inside the structure. There will be minimal infiltration humidity but the infiltration humidity will never be enough to bring the humidity levels up to healthy levels inside the structure for the inhabitants, plants, and furniture.

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Air Handler Water Coil Freeze Stat | Freezing Protection Control

Air Handler Water Coil Freeze Stat - Freezing Protection ControlAir Handler Water Coil Freeze Stat

Air Handler Water Coil Freeze Stat – The HVAC Air Handler Freeze Stat is a low temperature limit control and it is used mainly in commercial systems in the duct work on economizers or in air handlers just before any coil especially water coils. It is a safety and protection control to prevent extremely cold air from reaching the hot water or chilled water coils inside the air handler where the air enters from the economizer. Under ideal control set up if the freeze stat trips the economizer dampers close and the blower fan stops. This prevents coils from freezing. A frozen coil can bust open and will need to be replaced if it freezes thus the purpose of the freeze stat in HVAC air handler applications which utilize economizers for free cooling.

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Data Center Perforated Tiles for Cooling Servers

Data Center Perforated Tiles for Cooling ServersData Center Perforated Tiles for Cooling Servers

Data Center Perforated Tiles for Cooling Servers – There is a lot to consider with perforated tiles in data centers and depending on who you talk to you will get different answers. The server floor in a data center is typically built on a raised floor with cold air being pumped under the floor by large CRAH (Computer Room Air Handlers) or CRAC units (Computer Room Air Conditioners). This cold air is flows through the perf tiles and into the data center to cool the load of the heat the servers and other ancillary data center electrical equipment produce. The data center load is a sensible load as data centers do not have a lot of humidity in them from outside sources so the cooling equipment need only be capable of cooling the sensible load with little worry about any latent loads.

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Heating with Heat Pumps | HVAC Systems

Heat Pump Heat-Heating with Heat PumpsHeating with Heat Pumps

There are some people who say that heat pump heat is not as warm as other types of heat such as a hot water boiler or even a steam boiler. Even the forced air gas furnace gets more credit for providing better heat than the heat pump. Heat pumps are extremely popular in the southern states where the heating season is short and where the temperature rarely dips below 35 degrees F. The heat pumps in the southern states are usually utilize electric heating strips for those rare times the heat pump cannot keep up in those unusual times when the temperature in the south dips below 35 to 40 degrees. Some of the more expensive units use a secondary heat of gas in the form of a gas furnace for back up heat. Whatever people say we will attempt to dispel this myth that heat pump heat is not as good as other types of heat.

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York Air Handling Unit Chilled Water Coil

York Air Handling Unit Chilled Water Coil

York Air Handling Unit Chilled Water CoilThis coil is a cooling coil in a large commercial York air handling unit. The air handler serves approximately 80 VAV boxes and is responsible for providing cool conditioned air to all the zones the VAV boxes serve based on a set point determined in a DDC program and the chilled water coil seen here. The 80 VAV boxes that are served by this York air handler represent zones or temperature controlled areas. The air handler is responsible for delivering a certain volume of air to all the VAV boxes. The air handler is only capable of delivering cold air or tepid air from the plenum return. It has no mechanical process to produce warm air. If the VAV zones need heat they have hot water reheat coils in them. If the VAV zone calls for heat the damper limits the amount of air coming from the air handler and opens a valve to allow hot water to enter the reheat coil via a valve operated actuator. This heats the air coming from the air handler and provides heat to the zone.

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MONDAY, JULY 21, 2014