This is a custom device for reading differential pressure. The most useful example I can think of is monitoring your pressure drop across your air filter. This is a great way to know when to change your filter.
It is based on an ESP32-C3-MINI, which has native USB-C for flashing.
The pressure sensor part number will control the differential range that can be expected, as well as the accuracy (+/- 2%). I've chosen +/- 0.5kPa, which is about 2" of pressure drop. Most HVAC systems are designed to have a pressure drop of 0.1" (0.025kPa).
Be careful when setting this up - I'm sure you can damage the sensor if you expose it to too much differential pressure.
It can be powered by USC-C, or, by a wider range of input voltages on the screw terminals. It was designed for 24VAC, which is a common voltage used in HVAC systems. It can also work with a broader range of both AC and DC input voltages. The absolute maximum voltage for the switching regulator is 40VDC, which means up to around 28VAC. The minimum DC is approximately 9VDC.
It has a 500mA polyfuse directly off the screw terminal inputs to protect your HVAC system. The USB-C port is unfused and should be protected by the upstream device.
The USB-C port can be used to program. The first time, the reset button must be held. After this, all subsequent programming does not require access to the button.
There is also a header for the typical serial flashing with GPIO0(9) and EN exposed. It follows my eflashy32 pinout.
The PCB will fit inside a Hammond 1593KBK case. You can either cut (CNC) or 3D-print the faceplates. You can superglue some magnets in the case to have it stick to your HVAC system.
sensor:
- platform: xgzp68xx
temperature:
name: "Temperature"
pressure:
name: "Differential Pressure"
filters:
- offset: 40
Note the sensor accuracy is +/- 2%. It is quite sensitive to pressure changes, so you may with to use other esphome filters in order to smooth out the values.
The following are based on feedback from users. If you would like to contribute something you've found to work well, please let me know via pull request, GitHub issue, or email.
Size/Material | Sample Amazon Keywords | Comments |
---|---|---|
2.5mm ID, 4mm OD polyurethane | Pneumatic Tubing - Polyurethane Air Compressor Hose Pipe, Apply to Air Line Transfer (4mm OD 2.5mm ID) | Works well, a bit stiff |
1/16" ID, 1/8" OD silicone | 1/16" ID x 1/8" OD Pure Thin Silicone Tubing Food Grade Pure Silicon Tube High Temp Home Brewing Winemaking Silicone Hose Tubing, 26.25ft Length | Very tight fit, suggest other sizes |
2mm ID, 4mm OD silicone | Pure Silicone Tubing, 2mm ID x 4mm OD High Temp Food Grade Tube Pure Silicone Hose Tube | Works well |
3mm ID, 5mm OD silicone | Too loose! Do not use |