Slant/Fin VHG-100-CH, Installation And Service Manual

Page: 100 / 164

100
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
CH
WITH CONSTANT CIRCULATION SYSTEM OUTDOOR RESET
; CH
MODE
2
This mode is available to both Heating Only (VGH-CH) and Combi (VGH-CO) boilers.
When CH_Mode is set to 2, full weather compensator is chosen. For this mode an outdoor sensor has to be
connected. The CH_Setpoint is calculated in the same way as described in paragraph 11.9.2.
However, the demand does not depend on the Room Thermostat input but on the outdoor temperature and the
outdoor reset setpoint. When the outdoor temperature is below Warm_Weather_Shutdown (settable) CH demand
is created.
During the night an input signal from an external clock can lower the CH_Setpoint. When the RT input opens
CH_Setpoint will be decreased with Night_Setback_Temp (
PB 28 ). The RT input does not influence the CH
demand directly!
This can be done by connecting a relay contact or clock thermostat to terminal 12 and 13 on the low voltage
connectors of the boiler (see paragraph 10.3.1). The room thermostat is only being used in this function to switch
between a night setback temperature and a daytime temperature, there is always a constant demand for heat in
CH mode 2.
The Night Setback temperature can be set by using the installer password and changing parameter 28 in the boiler
parameters; the default value is setpoint - 50 °F.
Boiler Parameters
(25) Warm Weather Shutdn 72 °F
▲
(26) Boost Temp increment 32 °F
(27) Boost Time Delay 20 min
(28) Night Setback Temp . 40 °F
▼
Adjustable constant Circulation Parameters
Parameters Display menu # Level (Default) Value Range
CH_Mode PB 1 Installer 0 Mode 0 - 5
Warm_Weather_Shutdown
Set max. outdoor temp.
Above this temp. heat demand is blocked
PB 25 Installer 72 ºF (22 ºC) 32...95 ºF
(0...35 ºC)
CH_Setpoint_Diff
Adjusts the calculated CH setpoints
PB 3 User 0 ºF (0 ºC) -18...18 ºF
(-10...10 ºC)
Figure 11.21
Table 11.12