Siemens RWI65.02 - Maximum Economy Changeover (MECH); Unoccupied Heating and Cooling Mode; Night Purging

CM2N3204E / 05.2001 Siemens Building Technologies
4/20 Landis & Staefa Division
This function is intended to make optimum use of the cooling energy supplied to the
plant. Based on the measured differential of outside and room or extract air tempera-
ture, the plant is operated either with reduced amounts of outside air or with heat
recovery. The controller then overrides normal control and acts on position signal output
Y30 to position it to 100 % with HR (DC 10 V) or to Y30
min.
. This function can be
selected (DIL switch no. 3).
10
0
T
B4 < B1
B4 > B1
B4 > B1
10
0
10
0
Y30
[V]
min
Y30
min
Y30
00
B4 < B1
∆T
10
0
2 K
2 K
Y30
[V]
Y30
[V]
Y30
[V]
∆T
T
3204D02E
Mixing dampers
HR equipment
During non-occupancy periods, "Unoccupied heating mode" or "Unoccupied cooling
mode" is automatically used, provided enabling took place (can be set for each function)
and the respective preconditions are met. The factory set minimum operating time is 30
min (adjustable from 0 to 12 h).
"Unoccupied heating mode" becomes active when the set supporting level for heating
(adjustable from 0 to 30 °C) is reached. Heating is provided until the room or extract air
temperature exceeds the supporting level by 1 K. In that case, the fans run at speed I or
II (depending on the preselected speed). Outputs Y20 and Y30 with operating action " \ "
are disabled (0 %).
"Unoccupied cooling mode" becomes active when the set supporting level for cooling
(adjustable from 20 to 50 °C) is reached. Cooling is provided until the room or extract air
temperature drops below the supporting level by 1 K. In that case, the fans run at speed
I or II (depending on the preselected speed). Outputs Y10 and Y30 with operating action
" \ " are disabled (0 %).
During non-occupancy periods in the summer, this function is automatically activated if
– the function has been enabled
– both the room and the outside temperature exceed their adjusted limits, and
– the difference between room and outside temperature exceeds the set value.
If the function is activated, cool outside air is drawn into the building. In that case, the
fans run at speed I or II (depending on the preselected speed). Outputs Y10, Y20 and
Y30 with operating action " \ " are disabled (0 %). The factory set minimum operating
time is 30 min. It is adjustable (from 0 min to 12 h).
20
22
24
26
18
16
14
12
t
Nmin
T
[°C]
R/A
t
T
T
R
A
Room temperature
limit
(DtPnt 12)
Outside temperature
limit
(DtPnt 13)
Night purging active
(DtPnt 15)
End of
occupancy time
Beginnning of
occupancy time
Delta
(DtPnt 14)
3204D04E
Maximum Economy
Changeover (MECH)
Unoccupied heating
and cooling mode
Night purging
Function diagram