Advanced Duct Sealant Testing

Duct leakage is a major source of energy loss in residential buildings. Most duct leakage occurs at the connections to registers, plenums, or branches in the duct system. At each of these connections, a method of sealing the duct system is required. Typical sealing methods include tapes or mastics applied around the joints in the system. Field examinations of duct systems have shown that taped seals tend to fail over extended periods of time. The Lawrence Berkeley National Laboratory (LBNL) has been testing sealant durability for several years.

Duct Tape Durability Testing

Duct leakage has been identified as a major source of energy loss in residential buildings. Most duct leakage occurs at the connections to registers, plenums or branches in the duct system. At each of these connections a method of sealing the duct system is required. Typical sealing methods include tapes or mastics applied around the joints in the system. Field examinations of duct systems have typically shown that these seals tend to fail over extended periods of time. The Lawrence Berkeley National Laboratory has been testing sealant durability for several years. Typical duct tape (i.e.

Optimization of Aerosol Sensor Placement in Common Ventilation Ductwork

Aerosol detection in HVAC duct components is a critical component of contaminant detection and analysis. Incorrect placement of a sensor inlet within the ductwork can have a significant, deleterious effect on capture efficiency and sample accuracy. Computational fluid dynamics studies were conducted of straight rectangular cross-section ductwork and a 90° bend to determine flow patterns and simulations of particulate injections were made at various locations across the inlet. The resultant particle distributions were analyzed to determine the optimal placement for a sensor inlet.

Lärmbekampfung in RLT-Anlagen, Teil 2 Noise reduction in ventilation systems, part 2

The methods for estimating or calculating the noise reduction in ductwork are described. Information is given about noise propagation in straight circular or rectangular ducts and in ducts with diameters changes, bends, elbows or junctions. Noise reduction by air diffusers, filters, coils, is also presented, as well as noise emission by ducts walls.

Lärmbekampfung in RLT-Anlagen, Teil 1 Noise reduction in ventilation systems, part 1

This paper describes the precautions that have to be taken in design and installation of ventilation systems in order to reduce their noise. They concern fans, ducts and ductwork, air inlet and outlet, air diffusers, air handling unit.

Performance of thermal distribution systems in large commercial buildings.

A field study was carried out to establish the performance of five thermal distribution systems in four large commercial buildings. They were standard single-duct or dual-duct constant air volume (CAV) system and variable air volume (VAV) systems, serving buildings with floor area greater the 2000 m2. Reports the duct air leakage. The ELAs ranged from 0.7 to 12.9 cm2/m3 of duct surface area, and from 0.1 to 7.7 cm2/m2 of floor area.

Duct sealing.

Describes a recently developed technology from California which provides a way to duct seal installed residential systems in two to three hours. The Aeroseal technology uses a fan to blow a small quantity of dry adhesive particles through the temporarily seald duct system. With registers and the furnace blocked, the suspended sticky particles travel in the airflow toward the only place left for the air to exit - the cracks and leaks. As the air stream turns sharply through leaks, the particles are deposited directly on the edges of holes to create seals.

Static split duct roof ventilators.

Split-duct roof ventilators or windcatchers are used to provide both supply and extract ventilation to the spaces which they serve. However, buildings are often erected in conditions where there is no prevailing wind direction. An investigation into four and six segment windcatchers to determine their relative performances under different wind conditions was undertaken using scale models in a wind tunnel. Conclusions indjciate that six segment windcatchers have a more predictable, reliable performance in uncertain or variablewind conditions.

Glass fiber emissions from HVAC ductwork: a review of the literature.

Recent concerns have been expressed with regard to emissions of glass fibers from heating, ventilation, and air conditioning (HV AC) systems. In this literature review, over 350 citations were found, of which 10 reported original measurements of glass fiber concentrations associated with the presence of fibrous glass duct lining or duct board, and two yielded sufficient data from which emission rates could be calculated.

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