There are a number of things that will cause you to have heat in one or more sections of your home and no heat in other sections of your home. some homes have separate zones controlled by zone valves or a separate circulator or pump for each zone.
One simple way to determine if you have a zoned system is to count your thermostats, if you have two or more heat thermostats it is likely, you have a zoned heating system. If you only have one thermostat chances are you only have one zone, but even though you only have one zone with no zone valves and only one circulator or pump, you may still only have heat in one section and no heat in another.
Now go to your basement or wherever, your boiler is located, look the boiler over carefully and follow the heat pipes, look for zone valves (see the image above) or look to see if you have more then one circulator or pump.
Note: many boilers have an indirect hot water maker that will have it's own zone valve and or circulator/pump, this is separate from the home heating and does not count as a heating zone, unless you do not have any hot water.
Please locate your boiler gauge, it may look very different from this image but it should have both the temperature and the pressure displayed on it if the pressure is 10 PSI or more continue on this page, if the boiler is showing 0 PSI or less then 5 PSI please.
Your boiler temperature should be between 160 and 210 degrees Fahrenheit.
Please note: you can not always rely on the boiler gauge reading. please see stuck gauge.
To get the problem solved quicker please use the 24/7 Help Line.