A contractor came to add an additional hot water baseboard heater into our family room which is an add-on, because there was no heating element in this added room and we could not use the space in the Winter months. He did this by tapping into the baseboard pipe in the room adjacent to the family room. Before he installed the new pipe, the baseboard heaters in every room were working fine and the house stayed quite comfortably warm. But now, none of the baseboard heaters are emitting heat. They are all cold. The furnace is working just fine. He has bled the system multiple times and still nothing. What could be the problem? And what could be a possible solution?
You still may have a vapor lock. 'Bleeding" alone may not be enough. You need to find someone who specializes in circulating hot water heat. This system is far more complicated than forced air. If there is air in those lines, water won't circulate.
It's tricky to remove an air lock. Some key points to remember are
Higher pressure makes air pockets compress and thus move easier.
Using the pump to build pressure by closing a valve and suddenly opening it sometimes causes the pocket to move.
A purge and fill method is often piped in somewhere.
When doing any of the above, closing the expansion tank valve can help. Closing the valve stops the expansion tank from buffering sudden pressure changes which are what moves air pockets.
If you are unable to clear the lock, drop the system and add a purge station. It's basically just a shut off that isolates a drain cock at the farthest point from the makeup water station.