RHS HVAC/Heat pump activity monitoring
After installation of a geothermal HVAC system, it was desireable to log the 2 stage compressor and backup resistance heating activity. This has been added using Phidget 8/8/8 digital inputs 4-6. The method for triggering the events is a relay for each stage connected to the thermostat output signals. The thermostat outputs 24 volts AC. Any small relay with at least a set of SPST contacts will do the job. Using DPDT constacts will provide for some future uses that are yet to be thought up.
The following is a sample of a real time HVAC activity graph
