new mains

bubbad

double checking, the pics are my two boilers, showing where all lines return to boiler, a plumber(same one that installed boilers) told me this is where air main would go, is this correct, when venting this is the spot that would vent all the supply and riser lines at once, is getting air out of all lines the best place to locate the mains, third pic is longest supply and return just thought the pic may help

nicholas bonham-carter

Follow the main supply pipes from the boiler to various radiators, and then back to the boiler as dry returns The pipe should become vertical and drop down to the wet return, below the waterline height of the boiler. Dry returns should never be joined together above the waterline. The main vent(s) for each should be just before this drop. If it is easier, the antler for the vents can be mounted on the vertical drop, as high as possible.
A low pressure gauge will show you when you have enough main venting, by showing the back-pressure (resistance to escaping air), during the early stage of firing. When you buy the vents, look upon their cost as an investment, shortening the time for steam to get to the radiator takeoffs, and reducing your gas consumption on each cycle.--NBC

bubbad

thank you NBC for your answer,thats where I thought it went