OBJECTIVE
This technical information details the new PID cascade algorithm that can be selected within the OpenTherm page of the RegConfig Configurator.
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The following image shows, within the OpenTherm page of the RegConfig, the position of the Heating Cascade Algorithm Control section and the Secondary Heating Temperature Compensation section, closely related to the PID cascade algorithm:
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The cascade algorithm can be of three types:
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Attenzione: non utilizzare G0 in quanto è il generatore OpenTherm utilizzato con il prodotto DOT, non con il sistema REG, quindi nella logica di cascata non viene mai considerato.
Warning
Do not use G0 as it is the OpenTherm generator used with the DOT product, not with the REG system, therefore it is never considerate in the cascade logic.
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However, it is important to underline that “PID Cascade” and “Buffer Tank Compensation Temperature” are two different and separate functions, which can operate together or separately (e.g., the “Buffer Tank Compensation Temperature” can be also used for other types of cascade algorithms, and also for Parallel functioning), which incidentally “share” the same sensor, as the requirement for both algorithms is to monitor the “final” temperature provided by the group of generators.
Note
The “Buffer Tank Compensation Temperature” is not the subject of this technical part, which instead focuses on the “PID Cascade”.
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so, if we consider a delta T of 4 K and a delay T of 5 minutes before switching on a second generator, then the value of Pid I to be entered is 87 (1740 / 4 * 5). The lower the Pid I parameter, the more time will pass before an additional generator is added.
Note
The values 160 and 1740 were derived from formulas implemented for this specific algorithm!
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The lower part of the OpenTherm page shows for each generator the result of the heating/cooling and DHW requests (red box) and the feedback from the generators to the REG System (yellow):
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Highlighted in red you have:
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The OpenTherm page can manage both boiler via OpenTherm protocol (without dedicated firmware) and heat pumps or boilers via Modbus protocol with dedicated firmware. In yellow are highlighted the values transmitted by the boiler or the heat pump and are closely linked to how the generators’ manufacturer has implemented the OpenTherm protocol on the boiler or the Modbus protocol on the heat pump/boiler (always refer to the documentation of the generator or, in the case of dedicated firmware, to the documentation supplied with the firmware). By hovering the mouse over the various rectangles/squares, a tag with extended description appears:
Stato GeneratoreGenerators Status: indica in che stato si trova il generatore (G = guasto, R = riscaldamento, SA = Acqua sanitaria, F = fiamma, C = condizionamento, ecc.). Se non implementato nessun quadrativo verrà popolato con le spunte.
Temperatura mandata, Temperatura ritorno, Temperatura ACS [°C]: sono le letture dei sensori del generatore se presenti e/o se mappate nel firmware dedicato.
Pot.: potenza erogata dal generatore in %, in kW elettrici, in kW termici (fare riferimento al manuale del produttore della caldaia o al manuale del firmware dedicato).
Errore OT: errori Opentherm più frequenti (Ra = richiesta assistenza, Rr = reset remoto abilitato, Bp = Bassa pressione acqua, ecc.). Nel caso di firmware dedicato fare riferimento alla documentazione fornita per la decodifica.
Errore OEM: indicazione del numero dell’errore, fare riferimento al manuale del generatore per la diagnostica o alla documentazione del firmware dedicato.
Reset: reset dell’errore, funziona solo se implementato o se la caldaia lo gestisce, fare riferimento al manuale del generatore per la diagnostica o alla documentazione del firmware dedicato.
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indicates in which status the generator is (F = fault, H = heating, D = domestic hot water, F = flame, C = cooling etc.) If not implemented, no square will be ticked.
Water outlet temperature (T outlet), Water inlet Temperature (T inlet), DHW Temperature [°C]: are the readings of the generator sensors if present and/or if mapped in the dedicated firmware.
Pow.: power delivered by the generator in %, in electric kW, in thermal kW (refer to boiler manufacturer’s manual or to the dedicated firmware manual).
OT error: most frequent OpenTherm error (Ts = service request, Rr = remote reset enabled, Lp = low water pressure, etc.). In the case of dedicated firmware, refer to the documentation provided for decoding.
OEM Error: indication of the number of the error, refer to generator manual for diagnostic or to the dedicated firmware documentation.
Reset: reset of the error, it only works if implemented or if the boiler manages it; refer to the generator manual for diagnostic or to the dedicated firmware documentation.
EXAMPLE
Si ipotizza di avere selezionato 1 come numero di generatori Start e Minimo, mentre il numero Massimo è 9:
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L’impianto in oggetto ha 4 generatori OpenTherm:
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