Why don't my Radiators get hot?
We ended up bleeding the radiators, upping the pressure, and replacing the thermocouple.

After all of that, we discovered that flames had been shooting out of the front of the boiler and melted half of the valve, messing up the electronics for the pilot light. 

We ended up replacing the entire boiler since it was 35 years old anyway, but the reason for the issue was the messed up valve.