My circulator pump on my older Bryant boiler has been running continuous lately. I would have to go down and tap the aquastat litely and the pump would shut off. So I went to the local supply store today and got a new White-Rogers model #11B02 aquastat. It looked identical to the old one Icant find a model # on the old one. I got home took the old one off and installed the new one. The new aquastat only has two screws to connect wires to and the old one had three. I hooked it up using the two and it works but not like it did before. So after troubleshooting for an hour I called the store explained what was going on and they told me that this aquastat had to be installed on the boiler return line they do not sell the aquastat that I have that installs on the supply side. The problem I am having is the pump does not circulate right. With the old aquastat the boiler would turn on and heat up to 180degrees and then shut off. The pump would turn on shortly after and run until the water was 120degrees. The aquastat was set at 120degrees. The new aquastat does not turn on unless I set it at 150 or above and then is shuts off once the water drops below 150. Could someone please explain how to adjust this thing properly. I did pst this on the furnace forum by mistake and got a response. The person that responded said they have never heard of a boiler functionig like this before. Theres a good chance it is not working properly, but I would like to get it to work right. They said normally a th epump turns on with the boiler, it doesn't wait until the water temp reaches max temp. Any advice would be great I would like to get the boiler to run properly.

N j you sound very knowledgeable why would 1 rad out of 13 be cold .when I bleed it comes out with cold water also what could cause this problem thanks