In the winter, they sat inside the house by the ornate, cast-iron radiators that ringed the room with warmth. Down in the basement, a behemoth of a coal-fired boiler heated water. The warmed water became buoyant and rose upward toward the radiators. It displaced the denser cold water in the radiators, and sent it tumbling downward through the large pipes to the boiler where it too would be heated.

Systems such as these depend on natural convection. Hot water rises; cold water falls. It's a simple principle, but to make the system work well and heat evenly without circulators or controls the Dead Men had to be very specific in the way they laid out a job. They had to size and angle the pipes just so. If they made a mistake, the convective currents wouldn't happen and the house would be cold.

For more than 100 winters, the gravity-hot-water heating system in this old house had warmed the families who lived there because the Dead Men had done a superb job. But now, the new owner of the house was changing things. He was leaving the old radiators with their raised metalwork; they were far too beautiful to remove. Most of the old piping would also stay.

There would be a new boiler, of course. There would also be a circulator and zone valves, and controls. The new boiler would have a bypass line to protect it from condensed flue gasses. There would also be an air separator.

The new boiler would also have an additional zone because the owners had decided to extend the old house so they could have a larger kitchen. Their architect had done a good job of matching the addition to the original house. The heating engineer now had to figure out the best way to warm this new space.

After much consideration, the engineer decided to use two, recessed floor-convectors in front of the wide kitchen windows. He would also use a kick-space heater beneath the sink cabinet on the other side of the kitchen. He calculated the heat loss of the new kitchen very carefully and sized the convectors and the kick-space heater very accurately.

The architect liked the engineer's choice in heaters because the recessed floor-convectors had attractive brass grates that fit well with the home's Victorian character. The kick-space heater, well, it would be practically invisible under the cabinet.

The contractor installed the new boiler, made the changes to the system and piped the new zone. The general contractor finished work on the home and everyone waited for winter to arrive.

And arrive it did. That first winter was much colder than normal and the weather put the new kitchen zone to the test almost immediately.

It didn't work.

The homeowners called the heating contractor to complain. The temperature hovered around 62 degrees, even though they had the thermostat set for 72 degrees. The contractor went to the job and checked things out. Everything seemed to be working properly, except that the kitchen was too cold. He called the engineer.

The engineer showed up on the job and went over the mechanical aspects of the system. He could find no fault. He checked his heat-loss calculations, and they seemed fine. He turned to the contractor and said, "Well, what are you going to do?" This bewildered the contractor because he thought the engineer was in charge.