We recently bought a new house and are having a problem with our heating system. The air upstairs is significantly colder than downstairs, in fact you can feel the change as you go up the stairs. The air coming out of the vents upstairs is about the same as the cool room temperature. Downstairs is relatively toasty (we keep the heat at 65) and it feels like summer if you stand under one of the vents when it's blowing.

Any things we should try ourselves? If not, what type of professional do we need to call.