Strebel S-CB+ Series, Installation Operating & Maintenance Manual

Page: 84 / 125

S-CB
+
Boiler Range Manual
84
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.
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 flow 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 high (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”.
P5CK
P5CL
P5CB
Start heat demand calorifier
Time
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P5CB P5CK
P5CL