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.

Proper Humidity Levels and Factors for Home Comfort & Health - The Study of Psycrometrics

Proper Humidity Levels and Factors for Home Comfort & Health

Psycrometric Chart

Yes, that is psycrometrics and it has nothing to do with psychology. It is the study of air and its properties. It is used in HVAC by HVAC technicians and HVAC engineers to determine the contents and make up of air. The HVAC industry uses Psychrometric Charts to plot the contents and make up of air. Using the Psychrometric Chart a technician or engineer can determine the relative humidity, enthalpy value, dry-bulb temperature, wet-bulb temperature, dew point and vapor pressure if they have a few of the listed values. With this data engineers and technicians can solve problems or assign values and set points. For example, an economizer system that is controlled by the building automation system can be controlled by an enthalpy value. This value associated with an And Gate will only allow the economizer to open under certain conditions that will allow the mechanical cooling systems to shut down and take in free cooling from outside the structure. The temperature, humidity, and all the contents and make up of the air will be optimum for free cooling using the economizer. By knowing the contents and make up of air one can set up HVAC systems to work better and one can also use the data provided by knowing the contents and make up of air to troubleshoot problems with HVAC and building systems. Proper Humidity Levels and Factors for Home Comfort & Health - Indoor Air Quality and Humidity It is important to maintain correct levels of humidity in the home for many reasons. Comfort is on factor, indoor air quality is another factor, and saving energy is another factor. All three are related in one way or another but each are separate factors. If you reside in the northern climate regions where the average temperatures are less than 20° F you want the indoor humidity to be relative to outside air humidity. Temperatures about 20° F the recommended relative humidity inside the home or business is 35% to 45%. The construction of the home or business will also determine the amount of humidity. If you have vapor barriers and good tight windows and doors you need a good mechanical ventilation system. Humidity levels can rise above 60% causing excessive moisture inside the structure which will lead to mold, mildew, and possible water damage. Make sure you have a good mechanical ventilation system inside your structure to avoid moisture issues. Bathroom ventilation fans, hood fans over stoves, and other type of exhaust fans inside the structure pull out excessive moisture when cooking or showering. If you have this problem it most likely shows up in the form of mold growth inside closets, kitchens, bathrooms, and ceilings. Additionally, if you have excessive moisture problems your windows will frequently fog or have a lot of moisture on the windows.

Proper Humidity Levels and Factors for Home - moist and dry air problems & healthProper Humidity Levels and Factors for Home Comfort & Health - Low Humidity

Low humidity levels cause problems also. Static electricity, dry skin, dry sinuses, and other health problems including increased flu illness can occur. Additionally, low humidity levels cause problems with wood inside the home. To test for low humidity levels in the home make a glass of ice water and set it somewhere away from the kitchen or bathroom. If after five minutes water droplets do not form on the outside of the glass then you have a problem with low humidity levels in your house and you need to get a humidifier. If your structure is suffering from low humidity levels you will also feel cooler resulting in a desire to turn the thermostat up. Therefore adding a humidifier to the HVAC system will cause you to turn the thermostat down. The correct levels of humidity in your home can increase comfort, save you money on your utility bills, and make you healthier.

Proper Humidity Levels and Factors for Home Comfort & Health - Warm Air Expands

Remember that your furnace or heat pump DOES NOT remove the moisture from the air. The furnace or heat pump simply makes the air warmer and warmer air expands making the percentage of moisture in the air less than when it was cold. Relative Humidity is the amount of water vapor percentage that is in a given amount of air at a given temperature. Air is considered to be saturated with moisture when it reaches 100% relative humidity however you can quickly change the 100% relative humidity in air by increasing its temperature. Decrease the temperature and the moisture condenses from the air or it can be considered rain. When you heat the air you increase its volume and without a humidifier adding moisture to the air you are decreasing relative humidity. Adding a whole house humidifier to your home will always help maintain higher levels of moisture in the house and that will counter all the problems associated with low humidity levels. High Performance HVAC

Proper Humidity Levels and Factors for Home Comfort and Health

Air Handler Water Coil Freeze Stat – Freezing Protection Control

Air Handler Water Coil Freeze Stat - Freezing Protection ControlThe 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.

Read more ...

Data Center Perforated Tiles for Cooling Servers

Data Center Perforated Tiles for Cooling ServersThere 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.

Read more ...

Heat Pump Heat-Heating with Heat Pumps

Heat Pump Heat-Heating with Heat PumpsThere 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.

Read more ...

Rooftop Air Handler with Integral Heat Recovery

Rooftop Air Handler with Integral Heat RecoveryThis 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.

Read more ...