Slant/Fin VHG-100-CH Installation And Service Manual page 99

Boost function
The outdoor reset boost function increases the CH_Setpoint by a prescribed increment (Boost_Temperature_Incr)
if a demand for heat continues beyond the pre-set time limit (Boost_Time_Delay).
Boiler Parameters
(25) Warm Weather Shutdn
(26) Boost Temp increment
(27) Boost Time Delay
(28) Night Setback Temp.
These are parameters 26 Boost Temp Increment and 27 Boost Time Delay.
They have a default value of 32 °F and 20 min, so the function is switched off and can be activated by the installer
by increasing parameter 26 by a number of degrees. Also, the time can be set when this parameter will be active
in parameter 27 (now set at 20 min).
CH_Setpoint increases again if the demand for heat still is not satisfied in another time increment.
Setpoint adjustment
It is possible to adjust the calculated setpoint with parameter CH_Setpoint_Diff. The calculated setpoint can be
increased or decreased with a maximum of 50 °F (10 °C). The CH setpoint limits (Reset_Curve_Boiler_Minimum
and Reset_Curve_Boiler_Maximum) are respected while adjusting the setpoint.
Apart from the calculated setpoint the functionality is the same as described in paragraph 11.8.1.
Adjustable Outdoor Reset parameters
Parameters
CH_Mode
Reset_Curve_Design_Boiler
Sets high boiler CH setpoint when outdoor
temperature is equal to
Reset_Curve_Outdoor_Design.
Reset_Curve_Outdoor_Design
Sets the outdoor temp at which the boiler
setpoint must be high as set by
Reset_Curve_Design_Boiler.
Reset_Curve_Boiler_Mild_Weather
Sets low boiler CH setpoint when outdoor temp.
is equal to eset_Curve_Outdoor_Mild_Weather.
Reset_Curve_Outdoor_Mild_Weather
Sets the outdoor temp at which the boiler
setpoint must be low as set by
Reset_Curve_Mild_Weather.
Reset_Curve_Boiler_Minimum
Sets the lower limit for the CH setpoint
(minimum).
Reset_Curve_Boiler_Maximum
Sets the upper limit for the CH setpoint
(maximum).
Warm_Weather_Shutdown
Set max. outdoor temp. Above this temperature
heat demand is blocked.
Boost_Temperature_Incr
CH setpoint increment when heat demand
remains beyond Boost_Time_Delay.
Boost_Time_Delay
CH_Setpoint_Diff
Adjusts the calculated CH setpoint.
Table 11.10
Status variables
Actual_CH_Setpoint
Calculated CH setpoint, based on outdoor reset curve
Table 11.11
▲
72 °F
32 °F
20 min
▼
40 °F
Figure 11.20
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
display menu # Level
PB1 Installer 1
PB19 Installer 176 ºF (80 ºC)
PB20 Installer 23 ºF (-5 ºC)
PB21 Installer 104 ºF (40 ºC)
PB22 Installer 68 ºF (20 ºC)
PB23 Installer 68 ºF (20 ºC)
PB24 Installer 185 ºF (85 ºC)
PB25 Installer 72 ºF (22 ºC)
PB26 Installer 32 ºF (0 ºC)
PB27 Installer 20 min.
PB185 User
Default Value Range
Mode 0-5
32.....176 ºF
(0.....80 ºC)
-4.....41 ºF
(-20.....5 ºC)
32.....104 ºF
(0.....40 ºC)
32.....86 ºF
(0.....30 ºC)
68.....194 ºF
(20.....90 ºC)
68.....194 ºF
(20.....90 ºC)
32.....95 ºF
(0.....35 ºC)
32.....68 ºF
(0.....20 ºC)
1 – 120 min.
0 ºF (0 ºC) -18.....18 ºF
(-10....10 ºC)
Range
68...194 ºF
(20.....90 ºC)
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