I have a Utica gas fired hot water baseboard unit. I can not get the temp. in the house to go above 65 degrees. The furnace goes on and maintains the 65 degrees.

It could be a thermostat problem.

Carefully feel the hot water lines near the furnace and at the radiant terminals. If you notice a substantial difference, the system may be laden with air. Venting the air out will solve this problem if appropriate.