...
The programmable controller controls the heat pump. If the top of the thermal store is below the setpoint, 40°C in this case, and the supply flow rate is higher than the minimum required flow rate, the heat pump is activated. The heat pump has in this case 2 compressors. From the moment the heat pump is activated, the first compressor will start after a certain amount of time (= stage 1). If the temperature in the top of the thermal store isn’t met yet after a certain amount of time, the second compressor will start (= stage 2). Delays are used to avoid on/off behaviour of the compressors.
The PI-controller will modulate the 3-way valve to make sure the minimum required temperature of 30°C is met.
Controls
The setpoint temperature can be changed with the “C” Base Circuit outside the programmable controller.
...
deltaT = 2;
(= hysteresis temperature, for minimal and maximal temperature before activation, or deactivation, in °C)minFlow = 0.3;
(= minimal flow rate before activation, or deactivation, in m³/h)a = SP - deltaT;
(= minimal temperature for activation, in °C)b = SP + deltaT;
(= maximal temperature for deactivation, in °C)trap1 = 0.5;
(= modulation signal in stage 1, in % )trap1 = 1;
(= modulation signal in stage 2, in % )stageOnSwitchMinutes = 10;
(= time delay before activating a new stage, in minutes )stageOffSwitchMinutes = 5;
(= time delay before deactivating a stage, in minutes )betweenStagesTimeMinutes = 10;
(= time delay between stages, in minutes )
HP1 is enabled on 3 conditions:
The top of the thermal store is below 40°C.
Temperature outside higher is than -10°C.
Timer HP1 is higher than or equal to the time delay of 4 minutes.
HP1 is disabled on 2 conditions:
Temperature outside is lower than -10°C.
The top of the thermal store is higher than 40°C.
HP2 is enabled on 3 conditions:
Heat pump 1 is working.
The top of the thermal store is below 37°C.
Timer HP2 is higher than or equal to the time delay of 4 minutes.
HP2 is disabled on 2 conditions:
Heat pump 1 isn’t working.
The top of the thermal store is higher than 40°C.
The on/off valve of HP1 is enabled on 1 condition:
Temperature outside is higher than -10°C.
The on/off valve of HP1 is disabled on 1 condition:
Temperature outside is lower than -10°C.
...
The top of the thermal store is lower than 37°C.
On/off valve of HP1 is open.
The on/off valve of HP2 is disabled on 2 conditions:
The top of the thermal store is higher than 40°C.
On/off valve of HP1 is closed.
Notices/Remarks
The system can be further optimised by doing sensitivity studies. For instance, a sensitivity study can be done for the size of the storage vessel.
...
If the user changes the power of the end-units the thermal capacity of the condenser doesn’t change automatically. The user should implement a correct capacity corresponded with the thermal power of the heat pump.
...
heat pump.
...
Change the external temperature by a sine wave to the evaporation temperature of the heat pump
More information about the HP can be found in Heat pump.
Ground Source Heat Pump (GSHP) - HP stages
...
Under constructionIdem as the previous template, except this is a Ground Source Heat Pump (GSHP) instead of an Air Source Heat Pump (ASHP). The difference is specified in Heat pump.