An engineer is planning underground insulated piping for a small district heating system, which receives heat from a central boiler plant and distributes it to three separate buildings. He is planning what he calls a “primary/secondary” piping system.
An installer is asked to use a pellet-fired boiler to supply heat to two zones of low-temperature radiant floor panels. The system includes a three-way motorized mixing valve to reduce the supply water temperature to the distribution circuits.
A heating contractor who’s trying out his first wall-mounted mod/con boiler installs it as shown above. When buying the boiler, the contractor was told to use a pair of closely spaced tees to separate the boiler and distribution system.