Behavior In Different Operating Modes; Pump Overrun; Normal Operation (Heating Operation); Reduced (Setback) Operation - Siemens LMU54 Series Basic Documentation

Summary of all ∆T
parameters (cont'd)
No. DPA no. Parameter name
9 174 NqmodNenn
10 175 NqmodMin
11 188 NqmodMinBw
12 181 TkSnorm
13 173 TiAussenNorm
14 172 dTkTrNenn
15 116 dTkTrMax
167 KpDt
16 168 TvDt
169 TnDt
Behavior in different
operating modes

Pump overrun

Normal operation
(heating operation)
Reduced (setback)
operation

Shutdown mode

Heating up phase

68/171
Siemens Building Technologies
HVAC Products
Function
Speed at the design point
Minimum speed in heating
operation
Minimum speed in DHW
operation
Maximum boiler temperature
setpoint
Design outside temperature
at the design point
Design differential
Maximum temperature
differential of
Proportional coefficient
Derivative action time
Integral action time
To ensure safe startup of the modulating pump, a start kick with the maximum pump
speed (QmodMin) is given for 10 seconds each time the pump is activated.
On completion of the start kick, the value calculated from the heat demand will be
adopted.
In normal heating operation, the pump runs at reduced speed (reduced volumetric flow)
for the greatest part of the operating time and the flow temperature will be appropriately
raised.
On the software side, both ∆T limitation and ∆T supervision can be switched on or off.
When the modulating pump is running, maximum limitation of the flow temperature
according to the adjusted value is always active.
In reduced operation, it is always the reduced (minimum) volumetric flow that is used, or
the ∆T supervison is active.
If the ∆T limitation and / or the ∆T supervision are active, they also acts in this operating
mode. It then works the same way as in normal operation, the only difference being the
lower flow temperature level.
The modulation function of the pump is deactivated since the heating is shut down.
In order not to extend the heating up phase due to the reduced volumetric flow, the plant
is always heated up with the full volumetric flow «NqmodNenn» within the first 30
minutes after reduced operation (night setback) or after plant shutdown (night
shutdown).
Then, a change to the volumetric flow is made that was calculated according to the
current outside temperature.
Basic Documentation LMU54... / LMU64...
3 Functions
Setting level
Installer
Installer
Installer
Installer
Installer
Installer
OEM
∆T
control
OEM
OEM
OEM
Mandatory settings
OEM Installer
No Yes
No If required
No If required
No Yes
No Yes
No Yes
Yes If required
No If required
No If required
– If required
CC1P7494en
07.11.2002