Twin Tstat zoned heat pump master slave configuration two floor home.. purple=white. With the 4 relay's there's no back feed to master or slave TStat internal logic.
The yellow wire can control zone dampers either master or slave. If using zone dampers a 50VA transformer may be required. Relay's are 90-293 type aka peanut relay's, very small relay requiring mA of current to operate the device.
If a gas/ac configuration is needed use the green wire to energize the relay's and or zone dampers and set the TStat to electric heat mode.
This relay package is needed where temperature and or humidity exceed the operation range of electronics components, like in a attic, pool, kitchen or mechanical room installation.
