Welcome! Here are the website rules, as well as some tips for using this forum.
Bypass 3-way thermostatic mixing valve HELP
This is my second radiant setup and I decided to go simpler than my last house and use 3way thermostatic valves instead of the expensive electronic mixing valves. There was an existing HW baseboard loop that we cut out and converted to radiant heat. I piped everything based on the attached drawing, the only difference is the primary circulator is on the supply side not return. I attached photos of the installation. After I initially bled the system it worked great, the boiler bypass valve was at 135 and the radiant heat was a solid 110. For some reason it does not work anymore. The primary loop works and I can control the temperature but the secondary loop only goes to 80 degrees and the hot water stops at the first of the close spaced Tees when I put my hand there one tee is cold and the other is hot. I am scratching my head and haven’t had enough time to really troubleshoot this. I was hoping someone with experience can see some error I made or maybe I have trapped air somehow? The TACO circulator is making a slight noise sometimes so I wonder if there is something going on. If I shut the return valves on my manifolds and open the manifold purge valve the hot water from the boiler goes right in but as soon as I shut that valve its like the return gets stopped. I am getting flow through all of the radiant loops so water is circulating. What am I missing here? My boiler is very large so I probably could have just went with 1 mixing valve but I wanted to be safe.