I noticed on my new boiler that the installer used Vent-Rite #75 main vents. I can find information for Dole and Hoffman, but not Vent-Rite. I think they have been bought out. I wonder if anyone has the pressure spec for this vent? I know for this boiler there should be low pressure (about 3psi) mains. Also when installing main vents should they be located up above the mains on a length of pipe instead of right into the main? I know they close on pressure, but how about temperature?
They close on temperature and they are generally installed above the return, but not on an end of main tee. If this is a residential system, you shouldn't need to exceed 1/2 psig to heat it.