Minimum Temperature Differential At The Pressureless Header - Siemens RVA47.320 User Manual

Benefit
Description
Setting
Effect
Siemens Building Technologies
HVAC Products
6.8 Minimum temperature differential at the
pressureless header
•
Detection of a too high flow rate on the heat generation side.
Avoiding excessive return temperatures.
An excessive flow rate on the heat generation side and the resulting increase of the
return temperature is quickly detected and, if necessary, offset by shutting down one of
the BMUs.
1. Press the line selection buttons to select line 60OEM.
2. Press the + / - buttons to set the minimum temperature differential.
Setting range
0...20
The minimum temperature differential at the pressureless header prevents the return
temperature from exceeding a certain level.
The setting is only active when running time strategy 2 or 3 is selected (see page 35).
With running time strategy 1, the function is inactive.
When the return temperature rises to a level which is half a switching differential (
MTS/2) below the flow temperature (point a), the selected running time strategy 2 or 3
is switched over to running time strategy 1. This means that one of the BMUs is shut
down as soon as possible.
If the return temperature moves away from the flow temperature by one full switching
differential MTS (point b), changeover is cancelled again. This means that running time
strategy 1 switches back to the previous running time strategy 2 or 3.
[°C]
t
VL
=
MTS
=
t
RL
LZS2/3
LZS1
2379Z27
t Cascade flow temperature (B10)
VL
t Cascade return temperature (B70)
RL
MTS

Minimum temperature differential at the pressureless header

LZS1-3 Running time strategy 1 - 3
a / b Changeover points of running time strategy
Basic Documentation RVA47.320
Description of the OEM settings
Unit
K (°C)
a b
Factory setting
4
t
133/166
CE1P2379E
15.07.2002