• Categories Cloud
    This will be shown to users with no Flash or Javascript.
  • Directory Statistics
    • Active Links: 110873
    • Todays Links: 102
    • Active Articles: 4129
    • Todays Articles: 38

Trusted Site Seal

Error. Page cannot be displayed. Please contact your service provider for more details. (1)

Free Directory SubmitArticle Details

Commercial Gas Heated Makeup Air Units

Date Added: April 16, 2011 03:48:54 PM
Author: Susana Terli
Category: Computers and Internet: Consulting

Buffalo Fan Co. ia an engineering representative and developer of various types of gas-fired air makeup units for industrial building ventilation. Indirect-fired units burn the fuel and air mixture inside of a heat exchanger while the air traveling to the space passes over the outside of the heat exchanger. In this design, the products of combustion travel through a vent to the outside of the building. Direct-fired units utilize air that will be sent to the heated space for combustion without use of a heat exchanger. The products of combustion are mixed directly with large volumes of outdoor air. Such mixing is considered safe because of the high dilution ratio. Variable Air Volume VAV units have a varying supply air volume and work similar to the 80/20 design, however, the recirculated air passes through a bypass section instead of through the facility. This type of unit is used in applications where building pressurization is desired and where contaminants located in the space cannot be recirculated. Facilities that have indoor vehicle operation frequently accumulate carbon monoxide and associated noxious fumes. For such instances, a ventilation sequence can be instituted to limit this potentially harmful buildup. The pressurization units for these buildings could be fitted with a carbon monoxide detector with an initial setpoint of, for example, 50 ppm that would trigger an alarm and energize a time-delay relay. If the condition still exists after, say, five minutes, then the return air damper would modulate closed and the outside air damper would modulate to the 100% open position. A second setpoint of 100 ppm would initiate an alarm and eventually de-energize the burner. The dampers would then be positioned to enable the exhaust mode. After the carbon monoxide returns to a safe level, the sensor could reset the unit to normal operation. In addition to emergency ventilation to purge carbon monoxide, the pressurization unit can be used to provide a source of ventilation during warm and hot months of the year. A reverse acting thermostat would modulate the outside air and return air dampers to bring in more outside air to maintain the indoor setpoint. These units can also be fitted with either chilled water or DX cooling coils to provide tempered or conditioned air to the space during the summer. Direct-fired pressurization units are approximately 93% efficient, with much of the available energy in the burned natural gas being delivered to the space in the form of heat. The supply airstream absorbs the heat that would be normally lost through a flue or vent pipe as in the indirect-fired configuration. A feature of this type of equipment that is especially important in cold climates is its ability to keep the building slightly pressurized to typically at 0.01 in. wc. This reduces the infiltration of cold air, and when overhead doors are opened, the outside air dampers are modulated open to admit more air to maintain this level of pressurization. This feature also acts as virtual ductwork to distribute air where it needs to go: toward cracks or areas with open doors. Direct-fired pressurization equipment is capable of delivering plenty of ventilation to a facility when it is configured as the 80/20 system described previously. Infrared systems, however, may need to be supplemented with a separate ventilation system. With certain classes of facilities, the infrared system would not require additional equipment for ventilation, since large structures with many doors would provide enough natural ventilation through leakage. Gas-fired pressurization systems each offer good solutions to heating large structures such as warehouses, distribution centers, aircraft hangers, and manufacturing facilities. Situations that require significant ventilation favor pressurization air handlers as do facilities that generate dust, mists, and other contaminants. Cleaner environments with less intensive ventilation needs would do well to go with the infrared radiant heating approach. In very cold climates, it might be beneficial to go with a hybrid solution using radiant heat at the perimeter as the primary heating source and placing pressurization units at the center of the facility for ventilation and for pressurization when doors are open. Additional information can be found at the Buffalo Fan web site http://buffalofan.com/ahu.html. Susana Terlitsky Industrial Air Make-Up Systems Designer Buffalo Fan Co. http://buffalofan.com/fanblower.html http://buffalofan.com/fan.html
Ratings Average rating: (0 votes)

No Comments Yet.

Visual Confirmation Security Code

*Enter the code shown:  

  • Help
  • Featured Website
  • Natural Skin Care - Expederm
  • Twitter Ticker
    Twitter icon

    My tweets

  • Latest Links
  • Latest Articles
    Rudimentary Criteria In Roofing Described
    Examining Systems Of Roofing, The Options For Root Criteria For Roofing, Compared - Roofing Solutions, Thinking About Core Factors For Roofing