I am having a 3-ton geothermal HVAC system installed in an older 2-story home (1918) and the contractor is using an open air return in a former chimney chase due to space limitations. The entire HVAC ducting is part of the install. We formerly had baseboard hot water heat with an oil burner. The oil burner and chimney were removed as part of the construction. A supply duct was installed within the former chimney chase, but there was no room for a return duct. Is an open air return consistent with best practices and how will this affect air quality in the home?
The contractor spray foamed the majority of the chase (Demilec HeatLok 200), but there is still dust in the return. In addition, there is a sheet metal box that is attached to the foundation wall at the unit which is exposed to the foundation. Shouldn't this be enclosed and not exposed to the foundation?
Any help would be greatly appreciated.