Example Layout 1 - Viessmann Vitocrossal 300 Service Manual

Service

Example Layout 1

Matching the control unit to the heating system
Subject to the equipment level, the control unit must
be matched to the system. Various system components
are recognized automatically by the control unit and the
relevant codes are adjusted automatically.
H For the selection of an appropriate scheme,
see the following diagrams.
H For coding steps, see page 50.
System version 1
One heating circuit without mixing valve and DHW
heating (optional solar DHW heating)
Applications
Heating system with DHW heating
Main components
H Gas condensing boilers 26 to 57 kW
H DHW tank (dual mode)
H Solar thermal system
Function description
The boiler circuit eP and the DHW tank qP/qR are
regulated by boiler heating circuit controller 1.
The heating circuit and the DHW tank are supplied
by their individual circulation pumps eQ and qE.
Heating mode
The boiler heating circuit controller regulates the boiler
water temperature in weather-compensated or heat
demand dependent mode (= supply temperature of the
heating circuit without mixing valve).
DHW heating without a solar thermal system
If the temperature falls below the set DHW temperature
selected at control unit 2, the burner of boiler 1 starts
and circulation pump qE of DHW tank qP or qR runs.
Within the program set at control unit 2, DHW is heated
with or without priority.
28
Vitocrossal 300 CU3A 26 to 57 Service
DHW heating by the solar thermal system
Solar circuit pump wE starts and DHW tank qR is heated
up, if the temperature differential between collector
temperature sensor wQ and tank temperature sensor qT
exceeds the start temperature differential.
Pump wE is stopped according to the following criteria:
H The actual temperature drops below the stop
temperature differential
H Exceeding the electronic temperature limit
(up to 90°C) set in the solar control module
(type SM1) wZ
H The temperature selected at high limit safety cut-out
qZ (if installed) is reached
Demands for the auxiliary function are met by
circulation pump wR.
Suppression of reheating of the DHW tank by the boiler
in conjunction with solar control module (type SM1)
Reheating suppression takes place in two stages.
Reheating DHW tank qR by boiler 1 is suppressed
as soon as DHW tank qR is heated by collectors wP.
For this, the set tank temperature for reheating is
reduced by boiler 1. Suppression remains active for
a certain time after solar circuit pump wE has been
switched off.
In the case of uninterrupted heating by collectors wP
(> 2 h) boiler 1 will only reheat, if the set tank
temperature (coding address "67") selected at boiler
circuit control unit 2 is not achieved.
In control unit 2, coding address "67" defaults a third
set DHW temperature (setting range 10 to 95°C). This
value must be below the first set DHW temperature.
DHW tank qR will only be heated by boiler 1 when
this set value is no longer achieved by the solar thermal
system.
Function/system
components
Operation with LPG
Code
Adjust Delivered condition
82:1 82:0