Old mixing valve style device

pipers

What exactly is this and if it fails can it cause a (hydronic) boilers safety valve to discharge

Big Ed_4

Looks like some zone control, Are they still connected ? To a relay ?

dko

https://heatinghelp.com/heating-museum/sarcotherm-installation-instructions/
https://archive.org/details/SarcothermWeatherControlForHowWaterHeating/page/n1/mode/2up

EdTheHeaterMan

pipers said:

What exactly is this and if it fails can it cause a (hydronic) boilers safety valve to discharge

Anything is possible, however, I don't believe that the relief valve discharging is related to a failure of the Sarcotherm mixing valve. It is more likely that your relief valve is discharging for another reason. Check the usual subjects first. A waterlogged expansion tank, a automatic or manual system fill valve passing, or perhaps the relief valve just failed. How old is it? What is the boiler pressure gauge say the water pressure is, in the boiler?

pipers

All that was done just wanted more clarity on the Sparcotherm blender I apréciate the comment

ScottSecor

This might help.
https://www.spiraxsarco.com/learn-about-steam/control-hardware---self-acting-actuation/self-acting-temperature-controls

pipers

Appreciate the comments but it was the gas valve letting gas through the diaphragm and the boiler would stay slightly lit the safety would discharge do to no call for heat and pumps were not on

Ifollowinstructions

Luckily you didn't blow the place up, maybe time for an upgrade. Undocumented success!

mattmia2

Time to replace that with a modern combination valve.

Big Ed_4

Change the gas valve and clean the burners