The Halsey House has 6,000 square feet to heat, and there are seven zones heated by radiators, baseboards, and radiant heat. The basement boiler is a behemoth with a Frankenstein jumble of pipes, valves, controllers, and pumps.
One day it was too cold, and we traced the cause to a faulty circulation pump on the main superzone that controls four bedrooms, living room, parlor, and dining room. Brrr!
The pump was almost too hot to touch, and the pipes around it were cold. The motor of the faulty pump was seized, so no water was circulating. Pretty easy diagnosis.
Luckily the circulation pumps are standard, so it was a straightforward task to replace it. However we had guests and stores were closed, so there were a few pump swaps that weekend. We removed a pump on a seldom-used zone, put it into the main zone until we could get a new circulation pump.