One bedroom in a heating zone hotter than others

Question

I have a total of three zones for heat in my house. I have oil heat. There is a zone for my hot water tank, a zone for the living room, family room, kitchen/dining and a zone for the three bedrooms and bathroom, this setup basically splits the home in half, one half on one zone the other half on the other.

The thermostat that controls the "Bedroom" Zone is in the master bedroom right by the door. We keep it at about 65-67 (the thermostat is old and it's hard to tell, it is being replaced Friday)

The master bedroom and one of our kids bedrooms feels like it is in that range, however, in my other child's room the video monitor we have in there read 79, and when my wife went in to get him, she stated it felt like a hot box.

I'm not sure how this could be possible as all the bedrooms are on the same zone, so it's not like we can turn the heat up for that room only.

Layout of the rooms: Master bedroom is in the back corner of the home Second bedroom is across the hall in the other back corner of the home Third bedroom (same size as the second) is adjacent (right) to the second bedroom in-between the coat closet and living room (Living zone set to 68).

Not even sure where to look or what to look for as to me, logically it makes no sense, it's not like the sun is beating down on the room, the sun rises on the master bedroom side. It is a ranch and all rooms boarder an exterior wall and have one window per room.

UPDATE to reflect comments

• This is a ranch
• There is an oil burner that heats water pipes that run along the floor
• The two kids rooms are connected meaning the same pipe runs through one room and directly through the wall into the "hot" room.
• We had central air installed in Late April early May, there is a duct in each room and the thermostat that controls the air also controls the heat, we simply click mode from cool to heat
• The oil burner is in the garage at the other end of the house (house is a typical rectangle) with garage at one end and bedrooms at the opposite
• We just moved into this home in January so not a full year yet
• We have our boiler serviced per contract in January so they won't come until then unless something breaks to do the yearly servicing

Answer 1

Since you mention "oil heat" and "hot water tank", it sounds like this is an oil burning boiler, feeding hot water through radiators to the various rooms, with each zone controlled separately somehow.

Also not clear whether this is "always been this way" or "new problem".

If new problem:

Since the thermostat in the problem zone is in the room that feels normal, that indicates the thermostat is OK. Since the other rooms are hot, that means one of two possibilities:

• The normal rooms are not getting as much heat as they should, so the system keeps going until the thermostat says "stop", at which point the other rooms are overheated.
• The other rooms are getting more heat than they should, so the system cycles normally but those rooms get overheated.

My hunch is the first case. So the starting point would be to determine whether there are any issues with pipes, valves and radiators in the "normal" rooms. But probably check everything in that zone to be sure. Could be a partial blockage somewhere, a stuck valve or something else.

If always been this way:

You need to balance the radiators between the rooms. In a forced air system this would be using dampers or different sized ductwork to adjust the air flow to each room. With radiators, I assume (never done this myself because I've never lived with that type of system) this would be by adjusting valves so that flow is lower to some rooms than to others.