House not getting heated

I hate to ask this — but let's be sure this is really steam and not hot water? The radiators can look similar.

Assuming that it really is steam, next question is also kind of embarassing: the boiler is really running? It's not just a fan on the boiler burner that you are hearing?

There will be an inspection port where you can look in and see — if it's oil, is there a good bright fire in most of the firebox? If it's gas, is there a good bright blue flame on the burners or a good flame in the firebox?

I apologixe in advance if those questions seem obvious, but… it helps to be sure.

Now. If the boiler is really running, how much water is in it (where is the water level on the sight gauge) and what pressure, if any, is showing on the pressure gauge? when you go outside, do you see any steam — billows of white "smoke" coming out of the chimney?

Honestly, there isn't much that can go wrong with a steam system — if the boiler is producing steam, it has to go somewhere. You can feel along the pipes leading away from the boiler (careful — they may be very hot) to see how far the steam is getting.