Domestic Hot Water (Dhw) Piping - Tx151C & Tx200C (Combi) - NTI Trinity TX Series Installation And Operation Manual

Tx I&O Manual
DOMESTIC HOT WATER (DHW) PIPING – Tx151C & Tx200C (COMBI)
11.0
DHW Description of Operation
Tx Combi models incorporate a DHW heat exchanger (Brazed Plate) and the controls necessary to heat DHW
without requiring a separate water heater. When the internal flow sensor detects potable water flow in excess of
0.3gpm the controller operates in DHW mode, whereby the potable water is heated to the "DHW Setpoint"
(Installer Menu setting 2-07). Set "DHW Setpoint" to the desired hot water temperature; to avoid the risk of
scalding a Thermostatic Mixing Valve MUST be installed, see Figure 11-1.
Thermostatic Mixing Valve – due to the potentially high hot water temperatures exiting
the water heater, a thermostatic mixing valve (or equivalent anti-scald device) must be
installed according to Figure 11-1, local code and the installation instructions provided
with the thermostatic mixing valve, to reduce scald hazard potential. Failure to follow
these instructions may result in serious injury or death.
Scald Hazard - Hotter water increases the risk of scald injury. There is a hot water scald
potential if a thermostatic mixing valve is not used or is set too high. Be sure to follow
the adjustment instructions provided with the thermostatic mixing valve. Failure to
follow these instructions may result in serious injury or death.
A scald injury can occur when hot steam or liquid makes contact with one or more layers
of skin. Scald severity (degree of burn) is directly impacted by exposure time and
temperature. Refer to Table 11-1. The following basic precautions are common sense:
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DHW Preheat Mode
For improved domestic hot water comfort, the Tx-Combi incorporates a "Preheat Mode" feature (Installer Menu
setting 2-10). When set to ON the boiler control will function to keep the DHW preheated to limit the wait time
associated with a tankless hot water system.
Preheat Operation – Once per hour, the controller will operate the boiler in DHW mode, firing the burner at
minimum power until the boiler Return achieves a temperature within 25°F of the DHW setpoint. Note: if the
DHW or boiler Return temperature is within 34°F of the DHW Setpoint, Preheat mode will not initiate.
Young children and elderly adults burn more quickly and should use cooler water.
Never leave a child alone while drawing water in a bathtub.
Test the water temperature before bathing or showering.
Turn cold water on first and then add hot water until the temperature is comfortable.
│DHW Piping (Combi)
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