Frost Protection For D.h.w; Frost Protection In The D.h.w. Storage Tank; Frost Protection In The D.h.w. Storage Tank Flow; Frost Protection For The Secondary D.h.w. Flow - Siemens RVL481 Basic Documentation

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16.4

Frost protection for d.h.w.

The frost protection for d.h.w. provided by the RVL481 is ensured by sensors B3, B31
and B32. The behavior depends on the type of plant.

16.4.1 Frost protection in the d.h.w. storage tank

This type of frost protection is used with plant types x–1, x–2, and x–3. It always en-
sures a minimum switch-on temperature of 5 °C. If the temperature acquired with sen-
sor B31 or B32 falls below 5 °C, storage tank charging will immediately be started (in-
dependent of other settings), which generates a heat requisition to the precontroller.
The switch-off temperature is at 5 °C plus the switching differential (set on operating
line 128).
When using thermostats, there is no frost protection for the d.h.w. storage tank.

16.4.2 Frost protection in the d.h.w. storage tank flow

This type of frost protection is used with plant types x–2.
If the d.h.w. flow temperature (acquired with sensor B3) falls below 5 °C, the charging
pump starts to run. The mixing valve will not be opened and there will be no heat requi-
sition to the precontroller.
The switch-off temperature is 6 °C.

16.4.3 Frost protection for the secondary d.h.w. flow

With plant types x–4, no frost protection for d.h.w. can be provided since it cannot be
made certain that sensor B3 will acquire the temperature in the heat exchanger when
d.h.w. heating is switched off (circulating pump OFF).
Heating and D.h.w. Controller RVL481
16 Function block "Basic settings d.h.w."
CE1P2541en
20.05.2008