88
11.3.4 L
OW
/
HIGH FLOW TEMPERATURE TO TANK COIL
This function can only be
used for an “indirect” programmed boiler (parameter P4 AA = 1).
Normally for a regular calorifier a fixed flow temperature of 85°C is supplied to the calorifier heat exchanger in case
of a heat demand. This hot water flow will indirectly heat up the water in the calorifier tank.
The parameters for this function can be configured for both low and high calorifier operation.
This function operates as follows:
When there is a heat demand, the boiler supplies water to the heat exchanger of the calorifier, according to the flow
temperature set in parameter
P5 CB
. When the heat demand remains for the period set in parameter
P5 CL
, the flow
temperature set point will change to a higher temperature, which is set in parameter
P5 CK
. This situation continues
until the heat demand ends.
Curve and values only for illustration purposes, programmed parameter values can deviate!
The reason for this function is that the boiler by supplying a lower flow temperature to the heat exchanger of the
calorifier, can stay in its condensing mode (if the temperature is low enough) and thus operate at a higher efficiency
level. When it takes too long (>
P5 CL
) to heat up the tank with this low temperature mode, the flow temperature set
point will change to a higher setting to make sure that the hot water set point is reached:
P5 CB
Flow temperature Dhw tank low (display B2)
The low level flo
w temperature to the tank coil(s) in case of a calorifier/indirect hot water demand. This “two staged”
function is added to keep the boiler in the condensing mode as long as possible.
P5 CK
Flow temperature Dhw tank hi (display B3)
The high-level flow temperature to the tank coil(s) in case of a calorifier/indirect hot water demand.
P5 CL
Low Flow temperature time Dhw (display B4)
The programmed period for changing the set point of the water flow temperature from low to high.
The standard factory
setting for this function is “OFF”.
Low/high flow temperature to tank
coil.
P5CK
P5CL
P5CB
Start heat demand calorifier
Time
W
at
er tem
pe
rat
ure to
c
al
orif
ier h
ea
t
ex
c
ha
n
ge
r
