no heat in one zone- all baseboards

Hi there



I have a burnham seriese 2 model 204NCL LEI223 CGA 4.9.1969 boiler.



Problems: No heat out of one zone- all baseboards cold



So far

Checked thermostats- all work and valves make noise when turned up, switches in each zone make contact.

Took head of and verified that valve body turns loosely.



Gauge reads 192 degreess and at 18 psi



Question: when thermostat calls for heat and switch makes contact, how long does furnace remain on. When calling for heat it

only stayed on for a few minutes- 5 minutes. Is this normal?



Question: recirculation pump- comes on approximately every two - three minutes and stays on for 8 seconds, cycles through again



Is this normal?



4 zone system



one upstairs- 3 bedrooms

one upstairs- living room and dining room



one downstairs- west

one downstairs- east



all eat baseboards cold ( checked with infrared )



Question: if all thermostats are on shouldn't the furnace burners be on for quite a while until all pipes heat up?



Question: If i close all thermostats, and turn one one, how soon will it call for heat ( i.e. ) should the burners fire up

and stay on until temperature is reached.



Main Problem: east downstairs, pipe is cold above zone valve, all baseboards are cold?



I have included a diagram, if i need to shut down boiler in order to get water into it or reset system could you show me using hte diagram how i would do that



thanks

John andrews