We are in the process of getting quotes for HVAC replacement for a 2100 sq/ft 1950's single-story ranch in Dallas. The house is pier and beam and currently has a 10 year old Trane 5 ton 10 SEER system. The original ductwork was under the house in the crawl space, but has been removed due to poor installation and corrosion. Furnace and coil components are currently in a utility room, but we would like to move them to the attic. Goals are efficiency and air quality (filtration?). Different contractors have advised us differently on almost every issue. For example one says keep ducts in crawlspace (cooler than attic). The other says move ducts to attic as ceiling registers hitting windows will be more efficient... The current front runner is recommending:

• American Standard Allegiance 16, AccuClean, and similar furnace.

• insulated flex-duct moved to attic

• ceiling registers (aimed at windows /doors mostly)

• single return in hallway

Major questions:

• will moving equipment and ductwork to attic negatively impact performance/efficiency? Which is preferable--attic or crawlspace installation?

• how does one determine proper duct sizing?

• is the AccuClean worth the extra investment above the standard filter?

• does 5 tons sound too big for a well-designed/installed sytem in a 2100 sqft house in Dallas?

• can you recommned a great contractor in Dallas?