I would like to know how many wires and what size to hook into my robertshaw 9820i thermostat and where they go in the thmermostat to hook up to a goodman 31/2 ton 13 seer heat pump and a goodman air handler 3.5 ton the heat pump is a goodman GSZ130421 and the air handler is a ARUF42C14

Use a 7 conductor 18 AWG thermostat cable.

Stat------------------------------>Furnace-------->Heat Pump
Red wire to R--------------------R------------------R
Blue wire to C-------------------C------------------C
Green wire to G-----------------G
Yellow wire Y1----------------------------------------Y1
White wire to W2----------------Terminal 6---------W2
Orange wire O----------------------------------------O

Jumper E/w1 and W2 on stat.