Honeywell DHC, Service Manual

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SDC / DHC Hydraulic Components
EN2H-0221GE51 R0812 129
Separate start-up protection for heat generator and heating
circuits
This function allows separation of the temperatures for switching
on the burner and switching off the heating circuit when the boiler
temperature falls below the boiler minimum temperature limit.
5.2.4 "DHW" menu, pg. 77
7.1.2 Heat generator minimum temperature limit
To protect the heat generator from condensation formation, the
minimum temperature limit specified by the heat generator
manufacturer is to be set.
The heat generator switches on when the temperature falls below
the set value, while it switches off when the set value plus the
burner switching differential is exceeded. During heating, the set
limit value is not undershot.
The setting of this parameter is used solely for the response of
the heat generator (burner) to the set minimum temperature
(
WEZ
KT
−
min
). The function for the heat generator remains
unchanged.
The mode of operation of the set limit is defined via the "Heat
Generator" menu, heat generator start-up protection parameter.
There are three different modes of operation for the minimum
temperature limit:
Minimum limit based on demand
As long as there is no demand from heating or hot water, the
boiler remains switched off. The minimum limit is disabled. The
burner is switched on and the heat generator is heated up to the
set minimum temperature limit as soon as the temperature in the
heat generator drops below the fixed heat generator frost
protection temperature of +5°C.
Conditional minimum limit
The boiler minimum temperature acts as the lower limit, which will
be maintained even if there is no demand. The boiler is switched
off only if summer switch-off is active.
Unlimited minimum limit
See also
Function