NTI Trinity TX Series Installation And Operation Manual page 42

Boiler and Heating System Piping
Indirect Fired Water Heater – When installed as per Figure 10-5, the indirect fired water heater is in series
with the boiler during a demand for DHW. Therefore, its head loss, along with the head loss of the boiler and
associated piping, must be considered when sizing the circulator.
Figures 10-4 through 10-7 are examples of plumbing configurations using either single or multi system
circulators.
Figure 10-4: Single System Circulator Configuration (non-Combi) - Used in applications zoned with "Zone
Valves". During a demand for Central Heat, the boiler energizes CH Pump and Boiler Pump. The CH Pump
must be sized to provide adequate circulation throughout the heating system. During a Domestic Hot Water
(DHW) demand, the boiler de-energizes the CH Pump and energizes the DHW Pump and Boiler Pump. With
this configuration the Boiler Pump is the only circulator that causes flow through the boiler and it must be
sized in accordance with Table 10-4.
The piping configuration described above requires the Central Heating system and DHW
system to be de-coupled from the "Primary Loop" via closely spaced tees (Figure 10-4).
Figure 10-5: Multiple System Circulator Configuration (non-Combi) - Used in applications with "Zone
Circulators". This configuration requires the installation of a check valve located at each circulator. During a
Central Heat demand the boiler energizes CH Pump. During a Domestic Hot Water (DHW) demand, the
boiler de-energizes CH Pump and energizes DHW Pump. In this configuration both CH Pump and DHW
Pump are responsible for water flow through the boiler and must be sized in accordance with Table 10-4.
Figure 10-6: Single System Circulator Configuration (Combi) - Used in applications zoned with "Zone
Valves". During a demand for Central Heat, the boiler energizes CH Pump. The CH Pump must be sized to
provide adequate circulation throughout the heating system. During a Domestic Hot Water (DHW) demand,
the boiler de-energizes the CH Pump. The internal circulator of the Tx-Combi always provides the boiler
water circulation.
Figure 10-7: Multiple System Circulator Configuration (Combi) - Used in applications with "Zone
Circulators". This configuration requires the installation of a check valve located at each of the zone
circulators. The internal circulator of the Tx-Combi always provides the boiler water circulation.
Figures 10-4 through 10-7 illustrate typical piping systems. These piping schematics do
not illustrate all of the required concepts and components required to have a proper
installation. Concepts not shown include: prevention of thermal-siphoning (heat traps),
isolation valves, drain and purge valves, etc. It is the responsibility of the installing
contractor and system designer to determine which system best meets the need of the
installation and to consider all aspects of a proper system design.
modifications to these instructions may be required, based upon existing piping and
system design.
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Tx I&O Manual
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