Relays in board
In the DB are 24VAC/240VAC relays (VS116U). An Arduino and the circuit shown control a 24VAC power supply which controls the relays. The Arduino 'listens' to MQTT for a turn-off/turn-on command.
10x IN4004 Diode: Bought for $1 on ebay
10x NPN 2N2222 Transitor: Bought for $1 on ebay
Monitoring is via 4 temperature sensors, hanging in the unit. See "temperature monitoring".
This unit has control for: power (on/off), speed (1,2,3), 2 dampers.
Speed is hard to control and not necessary.
Power is controlled via a relay, as noted above.
Dampers are 24VAC units, drawing 200mA each. Therefore, 1000mA transistors will be