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Siemens Building Technologies
Basic Documentation RVA53.242, RVA53.242
CE1P2373E
Landis & Staefa Division
General control processes
26.03.2001
6.2 Maintained boiler return temperature
The boiler return temperature can be maintained at a certain level by using different
types of hydraulic circuits. It is possible to maintain a high level by restricting the heat
consumers or, more efficiently, by using a bypass with pump or mixing valve in the
return.
For these variants, various settings are required to ensure correct functioning.
Activate
Deactivate
a)
Maintained boiler return
temperature with mixing valve
No
Parallel
Maintained boiler return temp.
with bypass pump according
to the boiler return temp.
Maintained boiler return
temperature with bypass pump
parallel with burner operation
c)
e)
f)
No
Yes
Maintained boiler return
temp. through restriction
of consumers
b)
Yes
TKRx
Maintained boiler return
temperature ?
Maintained boiler return
temperature with
mixing valve ?
Bypass pump control ?
Bypass pump ?
d)
Influence of the consumers can be selected with setting OEM 21. The heat consumers
will be restricted by generating a locking signal. The function is based on the generation
of an integral as used with protective boiler start-up.
a)
Deactivation is possible by having the adjusted setpoint on line 22
OEM
smaller
than the possible actual value of the return temperature. Dies ist durch die
Standardeinstellung gegeben. This will have no influence from maintained boiler
return temperature.
b)
Maintained boiler return temperature is ensured only by restricting the consumers
(locking signal).
c)
The return temperature is maintained at the require setpoint with the help of
mixing valve Y1 and circulating pump Q2. The positioning behavior of the mixing
valve’s actuator can be adjusted on lines 41
OEM,
42
OEM
and 43
OEM.
d)
The return temperature is maintained with the help of the boiler bypass pump. For
that purpose, it must be assigned to the relevant output relay on lines 95/96.
e)
The return temperature is maintained with the help of the bypass pump parallel to
the burner signal.
f)
The return temperature is maintained at the adjusted return temperature setpoint
(line 22
OEM
) within the “bypass pump switching differential” (line 23
OEM
) with the
help of the bypass pump in on / off operation.
Description
Decision diagram
Explanation of the
diagram