Honeywell R7426A Manual Do Utilizador

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

EN1B-0203GE51 R0507C 

8 

 

These configuration parameters are only available on 
controllers with RTC. The configuration parameter AddHour 
or SubHour are required to adjust the month for 
summer/winter time change or vice versa. 
The actual clock is incremented by one hour at 2:00 on the 
last sunday of the month for winter/summer time change 
(AddHour). The actual clock is decremented by one hour at 
2:00 on the last sunday of the month for summer/ winter time 
change (SubHour). 
 

The configuration parameter PSTG_H or PSTG_C are 
necessary for the optimum start program on controllers with 
RTC. For heating and cooling applications, these parameters 
determine the prestart gradient to reach the comfort setpoint 
at occupancy start. 
If the comfort setpoint will be reached earlier or later than 
expected, the controller corrects the prestart gradient by self-
adaption routine to optimize the start cycle. 
The optimum start cycle for heating or cooling can be 
disabled by setting PSTG_H or PSTG_C to 0. 
 

This parameter is used by the self-adaption routine to 
optimize the energy consumption during the start cycle. For 
this optimization, a corrected prestart gradient is calculated 
once per day. The adaption to the actual prestart gradient for 
the next optimum start cycle is determined by the self 
adaption speed Adapt (0% = adaption disabled and 100% = 
max. adaption speed). 
 

The damper prestart time tvd is active with the optimum start 
program only and is used to set the time before occupancy 
start (scheduled comfort mode) at which the output signal Y1 
(damper) switches to normal operation to supply fresh air to 
the space in mixed air applications. 

The configuration parameter Adr sets the serial 
communication address. 
The serial communication bus allows the connection of the 
PC-based Operator’s Terminal to one or several controllers. It 
provides access to all application configuration and control 
parameters, time schedules, input and output values of the 
connected controllers and easy setting of these via the bus by 
mouse click or keyboard. 

Setting the control parameter DefProg to 1 resets all control 
and configuration parameters to defaults (see Table 4 and 
Table 5). Default programming is indicated by a display of def. 
After default programming, the parameter DefProg is reset to 
0. 
 

The main setpoint is either set by the control parameter W1 or 
by the external setpoint potentiometer if the configuration 
parameter CPATYP = 3, 5 or 6. 
 

For high or low limit control, the control parameter W

 is 

used as setpoint. 
During limit control, the throttling range Xp2 and reset time 
tr2 are active. 
Limit control will be active only if the T2 temperature signal 
(control parameter T2ext = 0) is available or alternatively the 
sensor T1 (control parameter T2ext = 1) is used also for limit 
control. 
For cascade control, the limit setpoint W

 

determines the 

control point at which the submaster setpoint

 

(W

) maintains 

the limit value and is not shifted anymore by the master 
control loop. 
High or low limit control is in accordance with the con-
figuration parameter LimTyp (C.13). 
 

The R7426A,B,C controllers provide cascade control which 
uses two control loops, master and submaster to maintain the 
master setpoint CTRP1. Cascade control will be active if 
temperature sensor T2 is connected and the control para-
meter W

 is set to any value other than OFF. 

This adjustment sets the control point of the submaster 
control loop, discharge temperature (T2), at zero room 
temperature deviation. If the room temperature deviates, the 
submaster setpoint W

 is automatically altered. 

Cascade control is disabled if the submaster setpoint W

 is 

set to OFF. 
Low limit of CTRP2 is performed if control parameter 
LimTyp = 0 and high limit of CTRP2 is performed if control 
parameter LimTyp = 1. 
 

The reset span adjustment R

 determines the reset effect in 

Kelvin. The submaster setpoint W

 is altered if the tem-

perature (T1) deviates by 50% of the throttling range Xp1. 
 

Proportional band (throttling range X

p

) adjustment determines 

the temperature change, required at the main sensor (T1) and