What is the difference between an STF and STR air curtain?

The front door models (STF) have 5 1/2" blower wheels to provide a lower velocity for customer entrances. The rear door models (STF) have 6 5/16" blower wheels for a higher velocity for insect protection on rear doors. • Are there damper plates on model STF air curtains? No, damper plates are not installed on front door STF models. These damper plates are available for field installation if the customer requires lower air volumes. • What is the difference between the following models: STF-1-60-2, STF-1-60-3? The STF-1-60-2 is constructed with two blower wheels and the STF-1-60-3 has a flexible coupling on the shaft to accommodate three blower wheels. • What Star series air curtains can be converted from "F" to "R" and why? The STF-1-36, STF-1-42, STF-1-48 and STF-1-60 may be converted to rear door models with larger blower wheels. This might be necessary if your customer requests a high velocity of air provided by the larger blower wheels. • Can we have multi speed motors installed ...  more