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Siemens Building Technologies
Basic Documentation RVP540 / RVP550
CE1P2488en
HVAC Products
Description of the heating engineer settings
18.10.2002
4.91 Priority with 2 heat exchangers
•
Type of priority with 2 heat exchangers can be selected
When using 2 storage tanks (buffer and d.h.w. storage tank)
or
2 heat exchangers in
the same storage tank, it can be defined if the solar collector shall charge the selected
priority storage tank (or heat exchanger) with relative or absolute priority. The storage
tanks can also be charged with no priority.
If solar swimming pool heating has been selected (ZuFu28, operating lines 175 through
177), the swimming pool will only be heated with priority 3 (storage tanks will be
charged first).
Assignment of the sensor / heat exchanger is explained on heating engineer operating
lines 305…308.
Setting range
Unit
Factory setting
1...5 –
4
First, the controller attempts to bring the priority storage tank to its setpoint.
As soon as the priority storage tank has reached its setpoint, the nonpriority storage
tank will be charged. Swimming pool heating is started only after the nonpriority storage
tank has reached its setpoint.
When both storage tanks and the swimming pool have reached their setpoints, first the
priority storage tank will be charged to its maximum charging temperature, followed by
the nonpriority storage tank and the swimming pool.
Then, the collector pump will be deactivated until it must be activated again due to the
“Maximum limitation of the collector temperature” (operating lines 300
EXP
/ 301
EXP
).
The following priority choices are available:
1
No priority
Both storage tanks (heat exchangers) are treated the same. The storage tank
with the lower temperature is charged first. The collector pump runs until the
storage tank temperature lies 5 K above the temperature of the second storage
tank. Then, the second storage tank will be charged until its temperature lies 5 K
above that of the first storage tank. So both storage tanks are charged alter-
nately until they have reached their maximum charging temperature.
2
Relative priority for buffer storage tank or heat exchanger 1
If the switch-on criterion is met (operating line 329), the buffer storage tank will
be charged first. As soon as the temperature setpoint of the buffer storage tank
is reached (operating line 456), charging of the d.h.w. storage tank is started.
If the switch-on criterion of the buffer storage tank is not met (
Δ
T too small), but
that of the d.h.w. storage tank is, the d.h.w. storage tank will be charged during
the “Maximum storage tank charging time” (operating line 304
EXP
). On comple-
tion of that period of time, the charging pump stops to check whether the collec-
tor with no load will reach the temperature level required for charging the buffer
storage tank. If that is the case, the buffer storage tank will be charged. If not,
charging of the d.h.w. storage tank will be resumed.
If the temperature differential required for charging the buffer storage tank is
reached during the “Maximum storage tank charging time”, buffer storage tank
charging will immediately be started. Charging of the d.h.w. storage tank will
continue only when the buffer storage tank is completely charged.
If neither the buffer nor the d.h.w. storage tank switch-on criterion is met, there
will be no charging.
Benefit
Description
Swimming pool
Note
Setting
Principle of
priority control
Effect
