Wirsbo/Uponor cosy replacement

This project is a replacement for Wirsbo/Uponor thermostat Cosy. The PCB is a drop in replacement of the old circuit board.

Original features

• Analog temperature setting with knob

New features

• Read/set wanted temperature
• Read/set upper and lower temperature hysteresis
• Read/set sample time of the thermostat
• Read state (Heat on , off)
• Read mode (Internal/external, Internal no home automation system found using analog knob temp, External controlled by home automation system)
• Fall back to analog knob temp setting if home automation signal is lost

Openhab integration

The below picture shows my integration to openhab

Building instructions

This project includes SMD component with pitch down to 0.5 mm.

Optional components

The following components can be left out (prepared for future)

• J2 pinlist (preparation for Display)
• U710 zero crossing detector (preparation for PWM)
• D1 ATSHA204 CryptoAthentication chip

Recommended assembly order

• Solder U5 (MAX 17552), as this is the most difficult component to assemble.
• Solder all SMD resistors and capacitors.
• Solder the rest of the SMD components.
• Solder pin components
• Solder T405-600 on back side