Control Of Pumps With No Speed Control - Siemens SIGMAGYR RVP540 Basic Documentation

Siemens Building Technologies
HVAC Products
• Maximum flow temperature T
Variant 1: Setting the maximum flow temperature defines the maximum flow tem-
perature setpoint.
Variant 2: Setting the maximum flow temperature defines the maximum flow tem-
perature setpoint on the one hand. On the other, the same setting defines the
range from what flow temperature the pump speed shall be increased.
T should always be selected as high as this is permitted by the heating system.
VMax
The higher T , the longer the pump runs at n
VMax
mum output will not be restricted unnecessarily.
•
Power factor LF
Of importance only in connection with variant 2.
Figure 1 shows that at outside temperatures below point C, the pump speed will be
increased from the reduced speed to the maximum speed. To define the rate at
which the pump speed shall be increased, the radiators' power factor is to be set.
The power factor defines the ratio of radiator output at the reduced pump speed
n and radiator output at the maximum pump speed.
red
Radiator
LF =
Radiator
This factor is fixed at 85 %. If the plant is correctly designed and sized, this setting
always ensures a satisfactory performance.
• Heating curve slope "s"
Variant 1: the heating curve slope must be set for the maximum pump speed.
Variant 2: the heating curve slope must be set for the reduced pump speed.
The correlation between the heating curve slope for the maximum speed s
the heating curve slope for the reduced speed s
s
nMax
=
s
nRed
LF
In the case of fixed value LF = 85 %, this means:
= 18 ⋅
s . 1 s
nRed nMax
6.7.5

Control of pumps with no speed control

If pumps with no speed control shall be controlled, the reduced pump speed must be
set to the level of the maximum speed.
Basic Documentation RVP540 / RVP550
General control processes
VMax
output at reduced pump
output at max imum pump
. Also, the heating circuit's maxi-
Red
speed
speed
is defined by
nRed
and
nMax
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CE1P2488en
04.11.2009