Custom Packaged air-handling units:
gas-fired, indirect and direct AHU
multi-zone ad mixed-flow AHU
for all types of industrial and commercial applications:
- Clean Rooms
- Food Processing
LONG SERVICE LIFE:We use premium quality industrial-grade materials and additional protective coatings for external surfaces and internal components of our Air Handling Units - to withstand the specific gases flow and the installation conditions of each application, industrial and commercial / institutional.
CAPACITIES:Up to 100,000 CFM for standard construction and larger, custom made on special request.
FLEXIBILITY:Every unit is designed for the specific installation and connections conditions. The unit floor area and its cross section dimensions are adjusted for precise room available at site.
EASY INSTALLATION:Packaged compact or sectional design provided with lifting arrangement and protections for easy transportation and handling / installation at site.
LOW MAINTENANCE:Service friendly design which provide large room inside cabinet, access doors, light and rigid floor ensuring accessibility to all components.
HIGH EFFICIENCY:Fans, coils, motors, humidifiers, filters, external insulation material, silencers, enclosure tightness, and other components are carefully selected and engineered for lowest energy consumption.
OPERATIONALLY SAFE:Safety devices and guards are provided in accordance to the international regulations and the customer specific requirements.
PRECISE PERFORMANCE:to match the customer capacities requirement utilizing the computerized selection for each component.
DIRECT AND INDIRECT GAS-FIRED AHUsCanada Blower makes two primary gas-fired AHU types: direct gas-fired and indirect gas-fired.
DIRECT GAS-FIRED AHUA direct gas-fired AHU has a gas burner installed directly in the outside makeup-air stream. The products of combustion (carbon dioxide [CO2], carbon monoxide [CO], nitrogen dioxide [NO2]) are discharged directly into the makeup air stream and supplied to the building area.
INDIRECT GAS-FIRED AHUAn indirect gas-fired AHU has a sealed combustion chamber where all products of combustion are discharged through a flue to the outside environment and no products of combustion are discharged within the make-up air supplied to the building. Such equipment also frequently is utilized for recirculating-air applications.
DIRECT-GAS-FIRED-AHU COMPONENTSThough simple in principle of operation, direct gas-fired AHUs have sophisticated burner-control systems. Unit sizes range from 1,000 cfm with a heating capacity of 80,000 Btuh to 100,000 cfm with a heating capacity of 15 million Btuh. Direct-gas-fired-AHU components usually include housings, supply fans, outside air intake hoods, intake dampers, filters and burners.
AHU HOUSINGSAHU housings are made of galvanized or aluminized steel. Access panels are provided to access dampers, filters, burners, and fans / motors. AHUs located outside are provided with a sloped roof and standing seam joints.
SUPPLY FANSFans typically are double-width double-inlet (DWDI) with forward-curved or backward-inclined blades. Fans can come with open drip-proof (ODP) or totally enclosed fan cooled (TEFC) motors. The most typical external static pressure in the 2- to 3-in.-wg range. Because most outside istalled air handling units can operate below 0°F, fan motors and bearings are rated to handle lower temperatures. For applications that require supply-air temperatures higher than 110°F, the motors and fan bearings are rated for maximum design operating temperatures when placed in draw-through configurations.
INTAKE DAMPERS AND HOODSOutside air intake hoods or weather hoods are designed for an installation specific location and usually provided with bird screens. Outside-air intake isolation dampers are furnished to prevent cold air from dropping through a unit into a warm building and warm air from escaping through a unit during winter months, when it is not in operation. Low-leakage parallel blade isolation dampers are most standard. The fan discharge is located at the opposite to isolation-damper position.
FILTERSA filter cabinet normally has 30/30 filters in a V-bank configuration to increase filter area and reduce static-pressure drop across the filters. Higher-efficiency filters are used on application.
BURNERSA burner consists of a cast-iron or aluminum pipe assembly with drilled gas orifices. The fuel-air mixing is controlled by perforated stainless-steel baffles attached to the pipe assembly. The burner can be placed in the outside airstream or in the outside / return mixed-air stream. But to prevent potentially hazardous combustion byproducts of indoor-air contaminants, the burner is placed in the outside airstream only. The required airflow across the burner must be within a specific velocity range (typically 2,500 to 3,500 fpm) for proper combustion. For variable airflow units, a modulating bypass damper or profile plate maintains the airflow velocity within the specified velocity range. Otherwise, the burner can experience inefficient operation, generate odors in the occupied spaces served, and create an un-safe increase in certain products of combustion.
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Liquid-to-Air Heat Exchangers
Air-to-Air Heat Exchangers
Air Handling Units
Specific to air handling
units, there are a number of ways to improve the performance of fan
systems. In HVAC systems, fans use roughly 40% of all electricity. The
problem is that even by following all of the proper procedures in
selecting fans for HVAC use, low total efficiency persists. From 2005
to 2009, the Energy Concept in Sweden conducted performance
measurements on 767 fans in HVAC systems. While a few of the fans had
an efficiency between 50% and 60%, the majority reached only 33% for
For the most part, there is tremendous potential for improving on energy consumption of fan systems. Whether commercial, residential, or industrial fans in Canada, as much as 50% electricity could be saved with a more efficient design, as well as better strategies for control. Below are some examples of how the performance of fan systems can improve.
Variable Frequency Drive – A Variable Frequency Drive (VFD) is designed to adjust the speed of an electric motor based on load. Therefore, the motor speed is reduced and energy is saved. The exact efficiency of the VFD alone varies since the nominal output along with partial load cause the drive to lose between 2% and 5% of torque and speed. However, by implementing a Variable Frequency Drive in many applications, performance improves and energy consumption drops.
Belt Drive – With a belt drive, there is a considerable loss of efficiency. The actual efficiency depends on the type of belt, complete gear adjustment, and the calculation of the belt gear. Under normal circumstances, efficiency is 90% when running at medium power, but with an incorrect gear adjustment, efficiency slips to 70% and even 60%. To boost performance, newly designed AHUs should avoid fans that are belt-driven, instead using direct driven-type fans that offer 100% transmission efficiency.
Aerodynamic Design – In a fan, dynamic pressure loss is expected. However, the aerodynamics on the fan hood is what dictates the actual amount of loss. As long as the fan hood is well-designed, it will give less dynamic pressure loss compared to a chamber.
Fan Wheel – For commercial and industrial fans in Canada, performance can be bolstered based on the type and design of the blades on the fan wheel. Efficiency up to 85%, which is the highest, can be achieved by using wheel type B. In this case, the blades curve backward. For greater airflow at smaller sizes of the wheel, a forward type wheel is often used. Unfortunately, this results in lower efficiency. In AHUs, it is important to always select backward curved blades.
The bottom line, the type of fan systems, as well as size, plays a key role in overall performance. For an HVAC system, the required performance of the fan includes size restrictions, airflow requirement, ambient temperature, and pressure, among other things. Therefore, the first thing you need to do is choose the right type of fan.
Typically, centrifugal fan systems in casing offer an efficiency slightly higher than fans without casing. In an AHU, there is more vulnerability to the effect of installation. Because this reduces the level of efficiency, a centrifugal fan without casing with backward curved blades provides the best performance.