A multiple boiler system is set up as shown in Figure 1. The objective is to add heat to the system in three on/off stages. 

A client asks a heating contractor to set up a floor heating system for a new 7,500 square foot machine shop.

An installer pipes up the system shown in Figure 1. Its purpose is to provide two zones of space heating.  

I recently had an inquiry from a designer who needed to combine some high temperature loads with low temperature loads. 

An installer is trying to wire up a two-stage heat pump for heating and cooling operation.

Figure 1 shows a hydronic system that's intended to supply four panel radiators, each with its own thermostatic radiator valve, and an indirect water heater from a gas-fired sectional cast-iron boiler.

An installer is asked to connect an old (but still working) propane-fueled cast-iron boiler, which was salvaged from another project, to a slab-on-grade floor heating system in a new workshop.

An installer is asked to pipe two independent zones of high mass floor heating to a conventional gas-fired boiler.

An installer was asked to include an air-to-water heat pump into a low-temperature radiant panel heating system supplied by a mod/con boiler.

A contractor is asked to design a hydronic heating system for a modest, super-insulated house in a cold Northern climate. The home’s design load is only 18,000 Btu/h. The owners are planning to install a 12 KW solar photovoltaic electrical system.