There is an old saying: a watched pot never boils. A better metaphor for patience is to guess the time it takes for a two-pipe hydronic system to changeover from heating to cooling. A design engineer asked to meet at a school building in what he described as “a challenging project.” I love challenges.
When I arrived, I saw the building had an old cast iron sectional boiler in dire need of retirement. There were several leaking sections. As usual, money was tight on this project. The system was a two-pipe system. During the heating season, heated water flowed through the piping. The water temperature was reset between 180° F and 140° F, according to the outside air temperature. In the cooling season, chilled water was pumped through the pipes.