If there isn’t any voltage, usually 110 volts for the US, then you need to examine why the motor isn’t getting power. I’ll do another article on that issue at the time.
So now we’ve established that you have electricity coming to the engine. There’s hot water from the boiler nevertheless the pipes going into the radiation are chilly. They are little-motorized valves which open and closed to direct the flow of heat to various areas of the home or building. It’s likely that one of these could fail and the circulator pump is operating and moving no water.
Changing the pump isn’t always a simple procedure. I will try to explain a few of the possibilities for changing out a circulator pump. To begin with, I’d recommend that if you’re reading this and you don’t have an additional circulating pump in the basement with the boiler.