21
Mode 3: Central Heating with Constant Temperature Loop
No outdoor sensor is needed. The supply temperature is
kept constantly at the setpoint temperature. The burner is
controlled in a similar way as Mode 0. When the room
thermostat contact closes the ch_setpoint will be decreased
with t_night_reduction. The pump is always on in this
condition.
6.4
DOMESTIC HOT WATER MODES
Mode 0: Disables Domestic Hot Water
No domestic hot water is available; therefore the DHW
sensor is not supplied.
Mode 1: DHW Storage Tank with Temperature Sensor
The DHW temperature in the tank is measured with a
storage tank sensor and set with parameter dhw_setpoint.
When the DHW sensor drops below ‘DHW_setpoint –
dhw_hyst_down’ the control detects a demand for the
storage tank and activates the pump. If the DHW
temperature continues to drop the ignition sequence will
begin. When the burner is lit the load is PID-modulated so
the supply is regulated towards DHW_setpoint. The burner
will fire at steady-state or it shall shut off if the storage tank
sensor is greater than ‘DHW_se dhw_hyst_up’. The
on-board pump will continue to circulate until the
dhw_post_pump_ period timer is satisfied.
With this mode of operation a Pre-Heat function is
implemented in the algorithm. If the storage tank sensor
detects that the temperature is below DHW_setpoint –
DHW_store_hold_warm
the boiler will initiate the ignition
sequence and the burner will fire at minimum fire until the
storage tank sensor temperature is
satisfies DHW_setpoint +
DHW_store_hyst_up.
The anti-freeze monitor on each boiler will monitor the inlet
water temperature and when it drops below 50
o
F (10
o
C) it
will bring on the pump to prevent freezing of the heat
exchanger.
Mode 2: DHW Storage Tank with Aguastat
When the aquastat closes the control detects a demand for
the storage tank and starts the pump. Operation of Mode 2 is
identical to the operation of Mode 1, but an aquastat
replaces the use of a sensor in the storage tank. The Pre-
Heat algorithm is not available in this mode of operation
Mode 4: Combination Boiler using Plate Heat Exchanger and
DHW Temperature Sensor
In this configuration the boiler can be used for space heating
and indirect domestic hot water. Camus supplies an on-
board brazed plate heat exchanger, a pump and a 3-way
diverter valve.
When a heat demand is detected the pump will run and the
3-way diverter valve switches over to the hydronic heating
loop. The pump continues to run until the ‘post pump CH
period’ is complete after cycling through a heat demand
cycle. When there is no heat demand the pump will turn off
Individually controlled zone pumps will draw hot water from
the manifold and return from the zone to the manifold.
The temperature of the water leaving the plate heat
exchanger is constantly monitored and when it drops below
‘dhw_setpoint – dhw_hyst_down’, the on-board pump
activates to satisfy a demand for DHW and the 3-way
diverter valve switches over to DHW demand. If a central
heating demand is present when a DHW demand occurs,
the heating demand will be interrupted resulting in domestic
hot water priority. The 3-way valve shall switch over from
hydronic heating to DHW demand and the boiler will
continue to function in this state until DHW demand ends. If
hydronic demand is still present after DHW demand ends the
3-way valve switches over to hydronic heating. This results
in zero lag, as the burner does not restart when switching
between hydronic heating and DHW demand.
Due to the use of a plate heat exchanger a Pre-Heat function
is implemented in the algorithm. This ensures the plate is
always warm and prevents the user from receiving an initial
blast of cold water when they first turn on the tap. The Pre-
Heat function is enabled after 2 minutes of burner shut off. If
the DHW sensor detects that the temperature is below ‘Pre
Heat setpoint – pre heat hyst down’ the boiler will initiate the
ignition sequence and the burner will fire at minimum fire
until the DHW sensor temperature is equal to the Pre Heat
Setpoint. The Pre Heat function will only activate when a
DHW demand is non-existant.
The anti-freeze monitor on each boiler will monitor the inlet
water temperature and when it drops below 50
o
F (10
o
C) the
pump will be activated to prevent the heat exchanger from
freezing.
Summary of Contents for DMC 753
Page 20: ...16 ...
Page 63: ...59 PART 14 EXPLODED VIEW PARTS LIST DYNAMAX WALL HUNG ...
Page 64: ...60 DYNAMAX FLOOR MOUNT ...
Page 71: ...67 PART 15 ELECTRICAL DIAGRAMS 15 1 DM 80 250 INTERNAL WIRING DIAGRAM WALL HUNG MODELS ...
Page 72: ...68 15 2 DM 210 750 INTERNAL WIRING DIAGRAM FLOOR MOUNT MODELS ...
