In this HVAC video, I replace an older A19 mechanical thermostat with an upgraded A421 digital control. The A421 includes many functions which include, Anti Short Delay, Sensor Offset for Calibration, Separate On/Off set points and more. On completion, I use the Testo 440 with 323 Air Quality Probe to verify. See some links below, Happy HVACing!
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Testo 440
https://www.testo.com/en-US/products/testo-440
A421 Controller
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.johnsoncontrols.com/-/media/jci/be/united-states/refrigeration/commercial-refrigeration/files/be_cat_penn_sselectronictempcontrols.pdf&ved=2ahUKEwj3qoGVmtnfAhWH94MKHRAwDWIQFjALegQIARAB&usg=AOvVaw2nzbHFiJly9NWbpY2CSlZi
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