So we just purchased a new house about a month ago in Northern New Jersey and I've been meaning to ask around about this boiler system because it's unlike the one we used to have in our old home with baseboard heaters. The problem is that one cast iron radiator is cold, and the rest of the radiators are fine. Normally I would open the bleeder valve (with the system on) and air would pour out and then hot water would follow. But on the radiator with a problem it actually sucks air in! Actually it seems like most of the radiators have a negative pressure!
A little background on the system it's an original Bryant gas furnace which pipes a 1 1/4" pipe loop around the entire house (one floor rambler + Basement). It has what I think is a Dirverter Tee valve for take offs for each of the radiators, which is what I'm confused about how that works. But it's a continuous loop, i.e. the large diameter pipe never stops.
So my question is how do I "bleed" the system of air, I tried sucking a little air out of the radiators with a venturi pump (didn't really do much), and that seemed to get a little warmth into the radiator bottom section. I was thinking of getting a vacuum pump like you use to bleed brakes, Not sure if that'll produce enough pressure though.
So all the radiators basically are in Parallel and the pump is mostly just forcing pressure through the large loop it seems. I couldn't find a way to bleed the main system like I am used to with my old baseboard (copper tube with aluminum fins) which had 3 seperate loops for each floor, and bleeding the air out of the system by the boiler usually fixed any issues.
I'd like to look at replacing this boiler in the near future, but I wanted to get a high efficiency condensing boiler, but with this configuration of the radiators all in "parallel" with a continuous large loop, it seems I may not get the temperature differential I need to take full advantage of the condensing efficiency?
Thanks for any help, I can grab some pictures if it's confusing. Hopefully this diagram helps.