Differential Temperature Control 2; Differential Temperature Control For Central Heating Backup; Thermostat Function; Solar Function With Central Heating Backup - Viessmann SDIO Installation And Service Instructions For Contractors

Function description – version with SDIO/SM1A
Version with SDIO/SM1A electronics module and...

Differential temperature control 2

If the temperature captured at temperature sensor 7
(TS3) is higher, by the selected start/stop temperature
differential (parameters 1599.0 and 522.3), than the
temperature captured at temperature sensor 10 (TS4),
then output 22 is live.

Differential temperature control for central heating backup

If the following conditions are met, output 22 is live:
There is a heat demand from one of the connected
■
heating circuits.
■ The temperature captured at temperature sensor 7
(TS3) is higher, by the selected start/stop tempera-
ture differential (parameters 1599.0 & 522.3), than
the temperature captured at temperature sensor 10
(TS4).

Thermostat function

Different modes of operation can be achieved by
determining the thermostat start temperature (parame-
ter 1598.0) and stop temperature (parameter 1598.1):
■ Start temperature < stop temperature:
Thermostat function e.g. for reheating.
Output is switched on when the temperature at
sS
sensor / TS3 falls below the start temperature.
Output is switched off when the temperature at
sS
sensor TS3 exceeds the stop temperature.
/
Start temperature > stop temperature:
■
Thermostat function e.g. for utilising excess heat.
Output is switched on when the temperature at
sS
sensor TS3 exceeds the start temperature.
/
Output is switched off when the temperature at
sS
sensor / TS3 falls below the stop temperature.

Solar function with central heating backup

The heating circuit return is channelled through the
solar cylinder, where it is preheated. If sufficient heat is
available from the collectors, reheating does not take
place, and the preheated return water flows directly
into the heating circuit. If insufficient solar heat is avail-
able for the water to flow straight into the heating cir-
cuit, it is reheated to the required flow temperature by
the heat generator.

Solar function with 2nd cylinder preheating

In a hydraulic scheme with 2 cylinders, the first cylin-
der is only heated by the solar thermal system. The
second cylinder is heated by activating the transfer
pump if sufficient heat is available in the first cylinder.
30
(cont.)
Note
Function can only be set during commissioning
Note
Function can only be set during commissioning
The temperature level is additionally monitored by sen-
sors (TS3) and (TS4).
/ aÖ
If the temperature differential between the heating cir-
cuit return and the solar cylinder is
between TS3 and TS4), the heat is made available for
central heating backup. If this temperature differential
falls below 4 K, central heating backup is no longer
possible.
If no solar heat is available, the second cylinder only is
heated by the heat generator.
The transfer pump is activated via the temperature dif-
ferential between sensors
8 K (differential
≥
(TS3) and (TS4).
/ aÖ