Duct cleaning: Do homes need it ?

This paper gives a description of the cleaning of metal ducts in small buildings, located in heating climates in the northern US states, with different cleaning techniques, their cost, and advices from different trade associations.

Implementation of a ventilation system with clean installation method

It is showed that side grinder produce significantly metal sheet dust onto the inner surfaces ofventilation ducts. New, cleaner installation method was developed in which shears are used asinstallation tools. The aim of this study was to carry out ventilation system installations atthree building sites with clean installation method and to collect information about operatingcharacteristics of the shears by interviewing assembly workers.The results of dust measurements showed that the average amount of dust on the inner surfacesof supply air ducts was very low in all three buildings.

Energy efficient duct design and control of VAV systems: where is the fan energy savings?

Energy efficient operation of variable speed fans in Variable Air Volume (VAV) systems ishighly dependent on both the type of duct design as well as the type of control strategy thathas been implemented in association with the volume flow demand profiles of each individualzone in the building. The quantification of energy savings due to duct design and the effects offan control have generally been poorly understood, even with very simplistic types of controlstrategies, e.g. static pressure P + I control which have often been employed.

Building envelope, duct leakage and HVAC system performance in HUD-code manufactured homes

Between 200,000 to 300,000 manufactured homes are built to the US Department of Housing and Urban Development’s Manufactured Home Construction and Safety Standards (MHCSS) in the US each year. This paper compares building envelope, duct leakage and HVAC s

Mineral oil residues on HVAC components : measuring methods

This paper presents a method to determine the amount of oil residues in HVAC components surfaces. That method has been validated. It appears that the oil concentration of studied HVAC components depends on the technique used for their manufacturing.

Effect of airflow and heat input rates on duct efficiency

Reducing the airflow and heat input rates of a furnace that is connected to a duct system in thermal contact with unconditioned spaces can significantly reduce thermal distribution efficiency. This is a straightforward theoretical calculation based on the increased residence time of the air in the duct at

Duct leakage in new Washington state residences : findings and conclusions

Many energy codes require that ductwork installed outside of the conditioned space be sealed. Prescriptive codes have no performance standard for what constitutes an acceptable level of duct sealing. Testing and anecdotal evidence indicate that many new homes have extensive leaks on both the supply and return sides of the heating system. A field study of 29 recently built homes was conducted in the Spokane, Washington, area. Systems were visually inspected; all defects were

Leakage of ducted air terminal connections : part 2, experimental esults

Leakage data for ducted air terminal connections are reported. The leakage flow rate generally varied from 1% to 8% of the total approach flow rate. Leakage was found to increase with the increase in the static pressure adjacent to the terminal for the unsealed condition. With marginal sealing of rigid ducts, leakage was found to be less than half that of the unsealed connection. The use of drawbands to mount air terminals to flexible ducts can reduce leakage at the collar to virtually

Leakage of ducted air terminal connections : part 1, experimental procedure and data reduction

An experimental study was conducted to estimate the leakage through air terminal connections to rigid duct and flexible duct. Air terminals from three different manufacturers were tested under different sealing conditions, namely, unsealed, marginally sealed, and fully sealed. Diffusers and supply grilles were tested in a blow-through test setup, whereas return grilles were tested in a draw-through test setup. The experimental procedure and data reduction are described.

Cooling performance of ground-coupled air intake ducts

This paper presents temperature and airflow measurements proving that ground-coupled fresh air intake ducts can have a significant cooling effect. Measurements at two Norwegian schools with such ducts, Jaer School and Medi School, show that the actual cooling performance after a three-day warm period is about 100 Wh/m2 of exposed concrete surface in the duct, with air velocity passing the surfaces of about 0.15 m/s. Our calculations indicate that this can rise to at least 200 Wh/m2 by increasing the air flow rate during the night.