Heat migration: On secondary loops that extend vertically to a load that is above the
primary loop, steps must be taken such as fabricating a thermal trap in the return piping -
minimum 18" (46 cm) drop - to prevent thermal siphoning and heat migration to the load
when there is no demand for heat to that loop. Alternatively, use check valves on both
supply and return of secondary piping.
Figure 30
Important Primary/Secondary piping details with closely-spaced tees
DHW indirect tank
Air handler
Low temperature radiant protected by a mixing valve for simultaneous heating during higher
temperature air handler operation. Boiler can return to lower supply temperature when
radiant alone is operating.
Figure 31
Primary/Secondary piping concept with simultaneous heating calls
49
3.8.2 System piping
Summary of Contents for EX Series
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Page 121: ...Appendices Wiring diagrams Figure 73 Controller electrical diagram 119 Appendices...
Page 122: ...Figure 74 Internal wiring diagram EX 400 and EX 500 models 120 Section Appendices...
Page 123: ...Figure 75 Internal wiring diagram EX 700 and EX 850 models 121 Wiring diagrams...
Page 124: ...Figure 76 Sequence of Operation 122 Section Appendices...
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Page 128: ...126 Boiler parts diagram EX 400 and EX 500...
