In this configuration the buffer is hydraulically connected between heat generators and the consumers and you never need a changeover valve. During charging control the output “ChgOverValve” has the value “0”.
A buffer lower (or middle) sensor is mandatory to stop the charging, when the buffer is completely loaded up to the selected level. To charge the buffer to a certain level, you can connect the bypass valves.
To be open for future improvements the buffer has an input “BufLoadLevel” to define the level the buffer shall be loaded from the controlled heat generators. The loading level can depend on:
When the input “BufLoadLevel” is set to a certain value, the buffer will never be charged more than down to the specified level.
This is achieved by the definition of the effective lower sensor. If the sensor specified in the buffer load level is not configured (input = 999), the effective lower sensor will be the next sensor placed at an higher level than the specified one.
In the extreme case, if only the upper sensor is available, this upper sensor would be the effective lower sensor, regardless of the “BufLoadLevel”.
The effective buffer lower temperature depends on the input “BufLoadLevel”.
if BufLoadLevel = 1, EffLowerTemp = BufMid1Temp
if BufLoadLevel = 2, EffLowerTemp = BufMid2Temp
if BufLoadLevel = 3, EffLowerTemp = BufMid3Temp
if BufLoadLevel = 4, EffLowerTemp = BufLowerTemp
If one of the sensors is not configured, the “EffLowerTemp“ will automatically switch to the next higher connected sensor (value different of “999”. See the next table for different configuration options.
Table 2. Lower Sensor Configuration Examples
Configuration |
Config 1 |
Config 2 |
Config 3 |
Config 4 |
Config 5 |
Config 6 |
BufUpperTemp |
mandatory |
mandatory |
mandatory |
mandatory |
mandatory |
mandatory |
BufMid1Temp |
<> 999 |
<> 999 |
<> 999 |
<> 999 |
<> 999 |
999 |
BufMid2Temp |
999 |
<> 999 |
<> 999 |
<> 999 |
999 |
999 |
BufMid3Temp |
999 |
999 |
<> 999 |
<> 999 |
999 |
999 |
BufLowerTemp |
999 |
<> 999 |
<> 999 |
<> 999 |
999 |
999 |
BufLoadLevel |
1 |
2 |
3 |
4 |
4 |
don’t care |
EffLowerTemp |
BufMid1Temp |
BufMid2Temp |
BufMid3Temp |
BufLowerTemp |
BufMid1Temp |
BufUpperTemp |
The heat generators will be switched off setting the output “HeatDemandOut” to “0” if:
EffLowerTemp > HeatDemandIn + CHG-01
The buffer starts to transmit the heat demand to the controlled heat generators to load the buffer if:
BufUpperTemp < HeatDemandIn – CHG-02
During external loading if the input „ExtLoading” = 1, the heat demand (if transmitted) will be decreased by the value defined in the parameter SOL-01 and the output “Buf_SpShift” will display the effective value of SOL-01.
When the input „ExtLoading” switches back to “0”, the heat demand at the input “HeatDemandIn” will be transmitted to the output and the output “Buf_SpShift” will be “0” after the delay time defined in the parameter SOL-02.
If combined external and own heat generators charging is possible, we recommend to set the parameter SOL-01 to a lower value, otherwise the heat generator charging would not be stopped.
Table 3. Parameter List Buffer Discharging Control
Description |
Value Range |
Default Value |
Unit |
CHG-01: switch to buffer hysteresis |
0 … 50 |
8 |
K |
CHG-02: start boiler(s) hysteresis |
0 … 50 |
5 |
K |