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Copyright © D 363 -06/99
Section C1 —Domestic Hot Water (DHW)
DHW DEMAND
A
DHW demand is generated on the 363 by one of two methods: either an external DHW demand from an aquastat or an internal demand
from a tekmar sensor.
External Demand
(
10K 2 = NONE
)
The 363 registers an external demand for DHW when a voltage between 24 and 240 V (ac)
is applied across the
Setp/DHW and the Com Dem terminals (5 and 3). Either a DHW
aquastat or setpoint control is used as a switch in the DHW demand circuit. Once the 363
detects a DHW demand, the
DHW Demand pointer turns on in the LCD and the control
operates as described below.
Internal Demand Sensor
(
10K 2 = DHW
)
If the
10K 2
setting is selected as DHW, the 363 looks for a DHW sensor connected to the
10K 2 and the Com Sen terminals (18 and 17). The
DHW TANK
setting is used to set the
desired indirect DHW tank temperature.
When the temperature at the DHW sensor drops 3˚F (1.5˚C) below the
DHW TANK
setting,
the
DHW Demand pointer turns on in the LCD and the control operates as described below.
An advantage to using the DHW sensor is that the control can display the current
DHW TANK
temperature and record the highest and lowest
DHW TANK
temperatures. Also, the 363 can
control the DHW temperature with more accuracy than when using an aquastat.
DHW DEVICE (
DHW THRU
)
Once the 363 has received a
DHW demand, the sequence of operation depends on the type
of DHW device selected. The DHW device is selected using the
DHW THRU
item in the
Adjust
menu.
DHW Valve
(
VALV
)
If
VALV
is selected as the DHW device and there is a
DHW demand, the 363 closes the DHW
Pmp / Vlv contact (9 and 10) and the Boil P1 contact (7 and 8). The boiler pump provides
flow through the DHW tank’s heat exchanger once the DHW valve is opened. The 363
operates the boiler to provide a sufficient boiler supply temperature to the DHW tank.
DHW Pump
(
PUMP
)
If
PUMP
is selected as the DHW device, the 363 assumes that the DHW pump provides
adequate flow through both the DHW tank heat exchanger and the boiler. To provide heat
to the DHW tank, the 363 closes the
DHW Pmp / Vlv contact (9 and 10) and operates the
boiler to provide a sufficient
Boil SUP
temperature to the DHW tank. If using a primary loop
with the DHW tank piped in primary / secondary, select
DHW VALV
.
BOILER TARGET DURING DHW GENERATION (
Boil 0TRG
)
The
Boil TRG
temperature during DHW operation depends on whether an external or internal demand is occurring. The DHW demand
overrides the reset water temperature.
External Demand
(
10K 2 = NONE
)
If the control receives a
DHW demand through an external device such as an aquastat, the
Boil TRG
temperature is at least as hot
as the DHW Heat Exchanger setting (
DHW XCHG
).
Internal Demand
(
10K 2 = DHW
)
If the control receives a
DHW demand from a DHW sensor attached to the 10K 2 and the Com Sen terminals (18 and 17), the
Boil
TRG
temperature is at least as hot as the
DHW TANK
setting plus 40˚F (22˚C).
DHW DURING UNOCCUPIED
The DHW operation during an
UnOccupied period depends on the type of DHW demand that the 363 is receiving and the type of setback
that is being used. For this function to operate, the control must have the
Setback / None DIP switch set to Setback.
Sequence, Section C
Section C1
Domestic Hot
Water (DHW)
Section C2
DHW Priority
Section C3
DHW with Low
Temperature
Boilers
Section C4
Setpoint
Section C —Domestic Hot Water (DHW) and Setpoint
24 to 240 V (ac)
3
4
Com
Dem
Boil
Dem
Setp/
DHW
5
Aquastat
17
18
Com 10K
2
DHW
Storage Tank
P
Pump
P
Valve
