Old CI, new boiler, need balancing help!

Josh_S

What is a good way to balance an old gravity CI system? I live in a house with 15 old cast iron rads that used to run gravity. The new Crown boiler was installed with a system bypass. There are three valves, one on the supply, on e on the return, and one in between the two. Circulator flows into the boiler and the expansion tank, freshwater feed, air scoop is on the return before the bypass and circulator. Now my question is, when I found it the bypass was throttled down but the return valve (before the expansion tank) was throttled wayyyyy down. Now if I open that full, will the second floor rads have a hard time keeping up? I have one thermostat on the first floor and it's all one zone. Any suggestions on how to go about this?

Ironman

Having the circ and the expansion tank and air separator on the return is definitely not the best arrangement, but if the cold static fill pressure is sufficient (at least 15 psi), then it should work. The return valve should be open.
Did the installer check for orifice plates in the rads and remove them where present?

Josh_S

Not exactly sure. This is the second boiler since the gravity conversion though (probably should have been more specific). Had some sort of Sears forced hw boiler before this. So to answer your question I don't really know for sure however the radiators do seem to heat up easily enough. We will have to see if opening the return will change that.

Ironman

Look under the system resources tab on the main site. Then go to Hot Water systems. Then go to Gravity systems. You'll find and article that explains how the plates should have been removed from the second floor rads and moved to the first floor ones when the system was converted to forced flow.

Josh_S

Opened it up, they must have moved the plates or at least taken then out. All the radiators hear up pretty evenly. Hopefully all stays good!