I have a rheem heat pump and recently changed the old thermastat to a honeywell 7400 programmable... everything seems to work fine, but since the change I have noticed a distint smell (sulphur/ozone?) anyone have any suggestions? Wondering if I may have a wire incorrectly installed?

If the wiring was burning the unit would have stopped by now. If you have a electronic air cleaner that could be causing a problem and need service otherwise you probably have the dreaded dirty sock syndrome and the interior A/C evaporator coil will need to be cleaned.