BC-HM VI.72.M4.02 Danfoss 11/97 27
Control principle
PI control of the temperature in the
charging circuit (S1) and ON/OFF
control of the storage tank temperature
(S2/S6). Charging temperature held
constant by motor valve control M in
heat exchanger primary circuit.
Circulation pump P1 controlled by relay
R1, charging circuit pump P2 by relay
R2.
Notes
- System (1-D and 1-E) is registered
automatically when sensor S2 is
connected (registered when the
control is connected to mains
voltage).
- One or two storage tank sensors (S2
or S2 + S6) can be used in this
system.
When two storage tank sensors are
used, the upper sensor registers cutin
temperature and the lower sensor
cutout temperature.
Charging of the storage tank starts
when:
P2.0 is less than P8.0 - P2.2 - P6.2
and stops when
P2.0 is higher than P8.0 - P2.2
(one sensor in tank)
P6.0 is higher than P8.0 - P2.2
(two sensors in tank)
- When cutout temperature is reached
in the tank, valve function depends on
the setting in P1.2.
P1.2 = 0 Valve closes, but the
system is frost protected
at 6°C (system 1-D)
P1.2 = 1 Charging temperature
maintained, but charging
pump stopped
(system 1-E).
- Charging pump connected to relay
output R2 is cut in and out on
charging demand and cannot be time
controlled in this system.
- Relay output R2 is not frost-protected.
- Cutout of charging pump delayed so
that heat residue can be utilised to
heat the tank. Charging pump
continues as long as there is at least
3 K temperature difference between
charging temperature and actual tank
temperature, but not longer than 3
minutes.
- Relay status in different operating
situations is as follows:
*
)
On changeover from normal to
Operating
Relay 1 Relay 2
condition
Standby 0 0
Reduced 0 **)
Normal 1*) **)
Frost 1 **)
reduced operation, R1 delayed 3
minutes.
**
)
Relay contact R2 controlled ON/OFF
when charging is demanded.
0 = open relay contact
1 = closed relay contact
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