Burned heating element
Even though the complexity of a heating system asks for a professional to repair it in case of malfunction, you could still learn some basic troubleshooting in the hope you can fix the problem yourself or at least tell the repairman what it is.
One of the problems that can occur is that the heaters blow air that is no longer hot. This could mean that the heating element has burned out.
Maybe in time the air flow in the house weakens more and more. This can indicate that the filter is dirty. The solution is to replace the filter.
When the breaker switches off than the system may shut off, so if this occurs remember to check the switch on the breaker. If it was thrown you can switch it back on and when this problem repeats call an electrician.