The piping strapped to the bottom of the floor joists is supposedly part of a primary loop.

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.

A designer needs to tie in an indirect water heater to a multiple boiler system. He selects a hydraulic separator for the project and connects the piping of the indirect water heater on the same side as the boilers.

The designer’s intent was to supply a low-temperature floor-heating zone, as well as a higher-temperature baseboard zone and air handler, from a thermal storage tank heated by a pellet-fueled boiler.

An installer sets up a zoned distribution system. To keep it simple, he uses the same size piping for the headers and all the distribution circuits. The heat source is a low-mass copper tube boiler with high flow resistance.

An installer who is used to boiler replacements may view the mechanical room aspects of changing from a boiler to a geothermal heat pump the same as a boiler changeout; just swapping out one “box” for another. Unfortunately, this can lead to some significant operating problems.

An installer pipes up a system using a conventional gas-fired boiler to supply heat to a low-temperature radiant panel system.

Due to the high price of fuel oil, a contractor is hired by a building owner to install a wood-gasification boiler to supplement the oil boiler. The building’s distribution system consists of a three-zoned air handler with hot water coils.

The three photos, provided by a friend of the industry, are all from the same hydronic heating installation.