DHW Valve (VALV) (See fig. b)
• If VALV is selected as DHW device and a DHW demand
exists, the control closes the DHW P6/Vlv contact (13 and 14)
and the Boil P3 contact (7 and 8)
• The primary pump provides flow through DHW tank’s heat
exchanger once the DHW valve is opened
• The control operates the Boiler contact to provide a sufficient
boiler supply temperature to DHW tank
DHW Pump (PUMP) (See fig. c)
• If PUMP is selected as the DHW device, the control assumes
the DHW pump provides adequate flow through both the
DHW tank heat exchanger and the boiler
• To provide heat to DHW tank, the control closes DHW P6/Vlv
contact (13 and 14).
• The control operates the Boiler contact to provide sufficient
boiler supply temperature to DHW tank
• If using a primary loop with DHW tank piped in
primary/secondary, select DHW valve
BOILER TARGET DURING DHW GENERATION
(Boil TRG) (See fig. d)
The Boil TRG temperature during DHW operation depends on
whether an external or internal demand is occurring. The
DHW demand then overrides the reset water temperature.
External Demand (Aquastat)
• If the control receives a DHW demand through an external
device such as an aquastat, the Boil TRG temperature is at
least 180°F
Internal Demand (Universal Sensor)
If the control receives a DHW demand from a DHW sensor
connected to the DHW S6 and the Com terminals (27 and 28),
the Boil TRG temperature is at least as hot as the DHW TANK
setting plus 40°F (22°C).
64
CONTROL FUNCTION
OVERVIEW
CONTROL FUNCTION OVERVIEW - CONTROL FUNCTION OVERVIEW - Section C - Domestic Hot Water
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