Honeywell R7426A Benutzerhandbuch

R7426A,B,C  TEMPERATURE CONTROLLER WITH AND WITHOUT REAL TIME CLOCK 

 7 

EN1B-0203GE51 

R0507C 

The controllers R7426B,C are supplied from the factory 
configured for sequence operation of heating, mixed air, and 
cooling control. 
The sequence operation can be configured for the following 
control applications by the control parameters YMode and 
Y1CTRF (see Table 8). Sequence control will be activated if 
at least one control parameter YxMode is not equal 4 
(R7426B, only). 

for cooling with three outputs 
(Y1, Y2, Y3) 

1 0  0 

for heating with three outputs 
(Y1, Y2, Y3) 

1 1  0 

with two outputs (Y1, Y3) for 
heating and one output for 
cooling (Y2) 

2 n.a. 

0 

with one output (Y2) for 
heating and two outputs for 
cooling (Y1, Y3) 

3 n.a. 

0 

damper, cooling and heating 
(Y1, Y2 and Y3) 

0 0  0 

energy recovery, cooling and 
heating 

0 1  0 

In the case of the three floating output controller R7426B, 
several ON/OFF sequence control functions can be selected 
by the configuration parameter YMode (see Table 9). 
 

6-stage ON/OFF 
sequence control 

1 

4 (x=1, 2, 
and 3) 

Y1,Y2,Y3 n.a. 

4-stage ON/OFF 
sequence control 
heating 

2 

4 (x=1 
and 3) 

Y1,Y3 

4-stage ON/OFF 
sequence control 
cooling 

3 

4 (x=1 
and 3) 

Y1,Y3 

15-stage binary 
coded ON/OFF 
sequence control 
H. 

5 n.a.  Y1,Y3 

according 
to 
Y2Mode 

two-position 
damper control 

4 n.a.  Y1 

Y2 and 
Y3 

1)

 

1)

 

individual (cooling and heating) 

 
In the case of the R7426B,C controller, the output Y1 can be 
configured for two-position damper control by setting the 
configuration parameter YMode to 4. 
 

If sensor T1 is used also for high or low limit control, the con-
figuration parameter T2ext must be set to 1. This inter-
connects the T1 and T2 input internally and the sensor has to 
be connected only to the T1 input. 
By using a limit temperate sensor T2, the parameter T2ext 
has to be set to 0 (default). 
 

The configuration parameter LimTyp allows the selection of 
high or low limit control. High limit control is performed if 
configuration parameter LimTyp = 1; low limit control is 
performed if configuration parameter LimTyp = 0. 
 

Three different sensor types can be used with the controller 
(see Table 10). 

Pt 1000 

-30....+130

°C 1000Ω at 0°C 

BALCO 500 

-30....+130

°C 500Ω at 23.3°C 

NTC 20k

Ω 

-30....+85

°C / 

-30....+130

°C

1)

 

20k

Ω at 25°C 

1) NTC sensor is detected automatically if, during power-
up, the sensor temperature is within -30....+85

°C and the 

configuration parameter Senstyp = 0. NTC sensor is 
selected manually if the configuration parameter Senstyp 
is set to 1. 

 
Automatic identification of sensor type is selected if the 
configuration parameter Senstyp = 0 (default). After power up 
reset, the controller detects automatically the type of sensor 
connected to the main temperature input T1. For correct auto 
detection, it is necessary that the measured temperature be in 
the specified range (see Table 10). The same type of sensor 
must be used for all temperature inputs (T1, T2 and T3). 
 

The R7426A controller performs cooling control if the 
configuration parameter Y1CTRF is set to 0. A rise in the 
measured variable will increase the output value (direct 
acting). The control action must be reversed for heating 
control by setting the control parameter Y1CTRF to 1. A rise 
in the measured variable will decrease the output value. 
If the configuration parameter is set to 2, the R7426A 
controller provides summer/winter changeover control by a 
potential-free contact connected to the occupancy input 
(terminals 1 and 4). 
In the case of the R7426B,C controller, the configuration 
parameter Y1CTRF has to be set to 0 (default) to perform 
mixed air damper control and to 1 for energy recovery 
systems.