Currently, I live with my grandpa, after 7 years I have been pretty-roughly introduced to the concept of hot-water heating via the radiators surrounding the basement, first floor and second floor apartment. We have constantly had issues with this type of heating, as it is a dated system, but here is what I have come to recognize over the past 7 years of working with him to get the apartments and basement warmed up.
Chances are there is air in the radiators.
I would check all the air bleeders on the radiators in the given area.
Bring a small bucket, an old rag/t-shirt, and a flat screwdriver.
- Set the bucket about 6 inches below the bleeder, and say 6 inches
- Put a rag over the bleeder hole
- Gently unscrew the bleeders, this will open it up and water should spew out, not all
the way, just enough so water leaks out.
- let it run, and allow the water to flow into the bucket, if it's in a not-so-easy spot
for the bucket, use the rag to sop up any water coming out.
- Check for a steady flow of water, check if it's warm, check if it's spitting out initially or indefinitely.
I have come to find that initially it will spit out a few times, indicating there was water in the line. Let it run til it gets about luke warm, maybe not, room temp. If it never does, and the heater is on, then you can isolate the issues.
Hope this helps. Cheers!