Overview Solar blocks: additional functions



The solar blocks Solar buffer basic, Solar buffer top/bottom, Solar 1 Boiler/Buffer, Solar 2 Boiler/Buffer and Solar 2 collectors exchanger/buffer have the same additional functions. They keep a solar system alive in summer and in winter and make the pump more comfortable: run-on, start-up time, PID speed, tube start, system protection, frost protection, collector and storage cooling, sensor monitoring, yield estimate and operating hours.

System protection and sensor monitoring are always active and cannot be switched off. The system protection uses the former switch-off temperature of the block (formerly Solar max.) as its threshold; an existing system is therefore protected after the update just as before, only with a reset difference instead of one Kelvin of hysteresis. All other functions are off by default, so the system behaves as before. Each of these functions is switched on with a check mark in the parameters of the block; its settings appear in the dialog only then.

The pump is still driven by the outputs of the solar block. The additional functions intervene where they have to switch the pump against the normal control. The separate block Solar system protection remains for systems that do not want to change their solar blocks; it uses the same logic.

Priority

If several cases apply, the topmost one counts. The priority is the actual content of the additional functions - whoever swaps it makes the system boil.

Rank Case Pump
1 System protection. The collector is too hot, the solar fluid would evaporate. Highest priority, also before frost protection. OFF
2 Sensor fault. The collector sensor is missing or outside the plausible range. OFF
3 Frost protection. The collector is about to freeze. ON
4 Collector cooling. The collector is very hot, but the storage is still below its upper limit. ON
5 Storage cooling. Excess heat is removed at night. ON
6 Lock. Enable 0 or lock not 0: the following cases are blocked. OFF
7 Normal control. The control of the block, limited by start-up time, minimum and maximum speed. per control
8 Run-on. The control has just switched the pump off. ON, time-limited
9 Tube start. Short flushing pulse while the pump is standing. ON, time-limited

Functions

Storage. The protection functions need the storage temperature as a limit. All connected sensors of the block with a plausible value count as storage (for example boiler and buffer, or buffer top and bottom). If none is connected or plausible, frost protection and collector and storage cooling are off - they need the limit, and without a limit a fault would boil or drain the storage. System protection and normal control keep working.

Valve in forced operation. Blocks with a changeover valve set the valve themselves in forced operation: for frost protection and storage cooling to the warmest storage, for collector cooling to the coldest. The upper limit of the collector cooling applies to the storage that is being charged.

Run-on. When the control switches the pump off, it keeps running for the set time and takes the residual heat out of the collector. At the minimum speed, without a minimum speed at full speed. If the control requests again meanwhile, the run-on is done. There is no run-on after system protection, fault or lock.

Start-up time. After switching on from standstill the pump runs at the maximum speed for the set time so that it starts reliably.

Controller. So far the speed works as a pure P controller: speed in percent = gain x difference. With controller I component (reset time) and D component (derivative time) it becomes a full PID controller. 0 switches the component off. The speed stays between minimum and maximum speed; below about 30 % no pump delivers reliably.

Collector set temperature. With a value above 0 the speed does not control the difference to the storage but this collector temperature: the hotter the collector above the setpoint, the faster the pump. With stratified charging this gives more usable temperature. Switching on and off stays with the hystereses of the block.

Tube start. With tube collectors the sensor does not see the temperature of the tubes while the pump is standing. Within the set time window, with the pump standing, every interval it is checked whether the collector temperature has risen by at least the minimum rise since the last check; if so, the pump runs for the flush duration, then the control decides again. Time window and interval are mandatory, otherwise the system pumps heat into the collector at night. The window may span midnight, equal hours mean the whole day. As long as the clock is not set, nothing is flushed.

System protection. Always active. Above the threshold system protection from collector (formerly Solar max.) the pump is switched off and released again only when the collector is below the threshold by the reset difference. It has priority over everything, also over frost protection - at 140 °C collector temperature there is no frost. The collector cooling must therefore be set below this threshold.

Frost protection. If the collector falls below the threshold, the pump runs and takes heat from the storage. It may give up: if the warmest storage falls below the minimum storage temperature, it switches off - frost protection that drains the storage does more damage than the frost. It starts again only after the collector has risen above the threshold plus reset difference.

Collector cooling. If the storage is full, the control stops the pump and the collector keeps heating up. The collector cooling lets the pump run anyway from the set collector temperature so that the system protection does not trip. It never runs beyond the storage upper limit: without this absolute limit the storage boils, and in a hot water storage that becomes life-threatening.

Storage cooling. In the time window excess storage heat is removed through the collector: it cools from the storage temperature on, ends at the target temperature, and only as long as the collector is colder than the storage by the minimum difference. As long as the clock is not set, nothing is cooled.

Sensor monitoring. Always active. If the collector sensor is not connected or outside the plausible range, the block reports a fault (SR) and switches the pump off. The range also applies to the storage sensors of the protection functions.

Yield estimate. An approximation without a flow meter: power = flow x density x heat capacity x difference between collector and storage. The flow is the value given for a full pump, proportionally at lower speed; blocks without speed calculate with full flow. Glycol is taken into account through its share. The block Heat meter works more precisely with a real flow.

Operating hours. Counts the hours the pump runs. After as many hours as the maintenance interval since the last acknowledgement, maintenance due is reported (WA). The values of operating hours, maintenance and yield are kept over a restart and are not synchronised through the controller group.

Inputs (in addition to those of the solar block)
FR Enable Optional. 0 blocks, not 0 enables. Blocked are the normal control, the storage cooling, the run-on and the tube start; system protection, frost protection and collector cooling remain, they protect the system. Not connected: the block counts as enabled.
SP Lock Optional. Not 0 blocks like Enable, 0 enables. Not connected: never locked. With the block Solar 2 collectors exchanger/buffer the existing input Lock (manual) keeps its meaning as manual/automatic: the outputs go to 0 once and the block sends nothing afterwards.
QI Acknowledge maintenance Optional. The change from 0 to not 0 is evaluated: the current operating hours become the new zero point, the maintenance message goes away. Only effective with operating hours switched on and a maintenance interval above 0. Not connected: the message cannot be acknowledged.

Outputs (in addition to those of the solar block)
SM Status text State in plain text for a text display, for example "Normalbetrieb", "Nachlauf", "Roehrenstart", "Kollektorkuehlung 128 C", "Frostschutz 1.0 C", "Gesperrt" (German, ASCII, written by the runtime). For a text address.
SR Fault 1 with a missing or implausible collector sensor (the pump is then off).
KK Collector cooling active 1 during collector cooling.
SK Storage cooling active 1 during storage cooling.
AS System protection active 1 as long as the pump is forced off because the collector is too hot.
FS Frost protection active 1 during frost protection.
WA Maintenance due 1 when the operating hours since the last acknowledgement have reached the maintenance interval. Always 0 without operating hours switched on or with maintenance interval 0.
BH Operating hours Total running time of the pump in hours (with two pumps: at least one runs). Counts only with operating hours switched on.
LE Solar power in kW Estimated power. Only with the yield estimate switched on; 0 while the pump is standing or the collector is not warmer than the storage.
ET Daily yield in kWh Estimated energy of the day; reset to 0 at midnight. Not reset while the clock is not set.
EG Total yield in kWh Estimated energy since the block was put into operation.

Parameters
Run-on time Seconds. 0 = no run-on (default).
Start-up time at full speed Seconds. 0 = off (default). Only for blocks with a speed output.
Maximum speed Upper limit of the speed of the control, default 100 %. The protection functions are not affected.
Minimum speed A switched-on pump runs at least at this speed, default 0 (none). With the block Solar 2 collectors exchanger/buffer the existing minimum speed applies.
Speed for protection functions Speed during frost protection, cooling and tube start, default 100 %.
Collector set temperature 0 = difference control (default).
Controller I component / D component Reset or derivative time in seconds. 0 = off (default, pure P controller).
Tube start Check mark. Default off. With from/to (hour), interval (minutes, default 30), flush duration (seconds, default 30) and minimum rise (Kelvin, default 2; 0 = flush at every check).
System protection Always active, no check mark. The threshold is the former switch-off temperature Solar max. of the block (system protection from collector, default 110 or 120 °C depending on the block, an existing value is kept); plus the reset difference, default 10 K.
Frost protection Check mark. Default off. Threshold 2 °C, reset difference 2 K, minimum storage temperature 15 °C. Needs a storage sensor.
Collector cooling Check mark. Default off. From 100 °C (must be below the system protection), reset difference 5 K, storage upper limit 95 °C. Needs a storage sensor.
Storage cooling Check mark. Default off. Time window 22 to 6 o'clock, from storage 70 °C, target 60 °C, minimum difference 5 K. Needs a storage sensor.
Sensor monitoring Always active, no check mark. Plausible range adjustable, default -40 to 200 °C.
Yield estimate Check mark. Default off. Flow at a full pump in l/h (default 300) and glycol share in % (default 30).
Operating hours Check mark. Default off. With the maintenance interval in hours, 0 = no maintenance message (default).

See also general parameters of all function blocks.