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Old 01-20-17, 11:25 PM   #6
Apprentice EcoRenovator
Join Date: May 2011
Location: Tortosa, Spain
Posts: 221
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The expansion module just gives me more outputs without the need to either use up GPIO ports on the esp or run extra cables. As it works on the I2C bus it uses the same 4 control wires as the ADC converter.

The outputs from the expander run 3 relays, 2 are on one of the little 2 relay boards that have all the driver circuit built onto the board. These run the fan and 3 way valve. The other is a solid state relay (SSR) for the compressor.

This is an old unit that has a capillary tube so there is no need to control an eev.
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