RBM wrote in :

On 1/15/2012 7:45 PM, BM wrote:
when i turn the thermostats on and off i can hear the circulator
pumps go on and off. the pipes that leave the boiler to the
baseboard and return to the boiler are too hot to touch. So i
wonder why the baseboars are only slightly warm. there are two
zones.


Lovely, a picture is worth a thousand words. One of the two
circulators is controlled by the triple aquastat relay, the gray box.
The other circulator is controlled by a Taco relay, the green box.
Your problem is not electrical. It is plumbing, possibly frozen lines,
or air in the lines.

Yep, could be a massive air bubble in the baseboard units (or elsewhere in the lines). To the OP:
do you know how to bleed air from the radiators?