You can connect 3 individual Transformers in a Wye AAutotransformer configuration, to achieve a 4 Wire Wye Voltage Boosting (or Voltage Bucking) setup of either 229Y/132v 3Ã˜ 4 Wire, or 249Y/144v 3Ã˜ 4 Wire - depending on how the Secondaries are jumpered.
Below are two Schematics for Wye connections to create a 4 wire Voltage Boosting setup (both demonstrate + 12VAC or +16VAC Voltage increase configurations).
Additional Schematics may be found in the Technical Reference Section.
Schematics found at page: Voltage Boosting Transformers-Wye Connected
Be sure to observe correct polarities on all primaries and secondaries, or you will have problems with balance, loading and idling.
If possible, first just see how much the Dryer suffers being run at 208VAC, then ponder the Voltage Boosting Autotransformers option(s). The heating elements will be driven at a lower Voltage, so they will draw a lower True Power (Wattage) at 208 VAC, as opposed to driven at 230 VAC.