Technical Instructions
RAB20 Series Two-pipe Fan Coil Room Thermostat
Document Number 155-526P25
March 2, 2007
Page 8
Siemens Building Technologies, Inc.
Maintenance
The room thermostat is completely maintenance-free. If inoperable, replace entire unit.
WARNING:
High voltage. Disconnect power before servicing. Metal part is not
grounded.
Diagrams
N
L
M1
AS
N1
G3
TH0508R3
Y
I
II III
G2
G1
L
ZV
W
AS
Aqua sensor (by others)
G1
Control output fan speed I
(Low)
G2
Control output fan speed II
(Medium)
G3
Control output fan speed III
(High)
L Operating
voltage
M1 3-speed
fan
N Neutral
N1 Room
thermostat
W
Valve output, heating
Y
Valve output, cooling
ZV Zone
valve
Figure 5. Wiring.
W
T[˚F]
ON
OFF
SP
SD
TH0488R3
Heating Mode
Y
T[˚F]
ON
OFF
SP
SD
TH0489R2
Cooling Mode
SD Switching
differential
SP Room temperature
setpoint
T Room
temperature
W
Valve output signal
heating
Y
Valve output signal
cooling
Figure 6. Operating.
