In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Was at a job today where we were hired to remove a cast iron rad so they could renovate. While we were at it owner had us replace the rad with one slightly smaller. Renovation is done so we connected it up and tried to fire it up today. The entire zone has no flow. (Technically we don't know if it had flow before we started this project).
Now..... some history. I replaced the boiler almost 30 years ago when I was working for a large company. At the time I was head of the hydronics dept. We installed 2 boilers. Primary/secondary. 6 zones. Cast iron radiation. Monoflo piping. Outdoor reset. I remember that the last time I was there 25+ years ago, everything worked fine.
The zone in question is original to the house. 1-1/4" steel with B&G venturi tees. Tees on the return of the rads. I have confirmed many times over it's not air. There are no high points in the piping. Dedicated risers off the main straight to the 2nd floor to each rad. Assumed it was a circulator issue. Replaced it today. No difference. No flow in any of rads. Got to following the main. By the way, the main is hot as hell. As I follow it around I see a set of tees where a rad was removed. We did it 30 years ago and the 2 tees are connected together with a jumper pipe. However, as I follow the main around I see 5 sets of tees where rads have been removed and installed onto a new loop to make a seperate zone. The old rad hookups are just capped. So now this 1-1/4" main only has 3 rads connected to it and it runs all the way around a large portion of the basement. Even though the 3 rads are right near the boiler they left the entire main and capped the pipes.
So the only thing I can come up with is the capped venturi tees are affecting the flow so much I am not getting any up to the rads that are still connected. By the way, when I replaced the circ (which was a Taco 0010) I first tried a 3-speed 0010 and then tried a 3-speed 00R. Neither pumping characteristic made a difference.