We have 3 zones on our boiler. The one in question runs the kitchen, living room, office and the master bedroom. The master bedroom is always 10-15 degrees colder than the rest of the house. The baseboard pipes are sometimes cold, sometimes warm but never hot. The boiler is approx 10 years old. Unsure if this was a problem before because we just bought the house from my aunt AND the house was remodeled before we bought it. Before the remodel the master bedroom was a living room and open to the rest of the house. A wall was added closing it off and ever since then it has been cold. There is no basement under the affected bedroom, it is a deep crawlspace (unheated) and 3 of 4 of the walls are exterior walls (north, east and west). Any help diagnosing or suggestions would be greatly appreciated!

I would try shutting down the other two zone thermostats and then increasing the setting on the cold zone. Then see if your boiler is firing to provide heat. Also see if you can hear the circulating pump runnning as well. If possible folow the water lines to the affected to zone to see if there are any bypass valves that may be restricting or diverting heat. Post back with your results. It would be helpful to know if there is adequate baseboard registers as well. It is possible to keep remodeling costs down this part of the job was "skimped".

You can also try taking the covers off the baseboard & looking on the ends for any type of bleeders. If you have what is called a mono or diverter tee system, there could be air trapped in that section of baseboard.