Residential Building cold water coil relief

[merimaga]

I am changing piping for a residential building from the boiler coils for two lengths each. I don't know what the proper name for the temperature relief valve that sticks out of the 2" brass elbow. I know it is there so that the coils don't burn and the water keeps cool when hot water is not in use. Don't know the proper name however. This is in nyc

 

[johnjh2o]

Post a picture.

 

[merimaga]

The valve is on the right side of the tee. Its a hose cog on the left.

 

[frodo]

crappy picture is that your low water cut off?