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Siemens Building Technologies Basic Documentation LMU54... / LMU64... CC1P7494en
HVAC Products 3 Functions 07.11.2002
3.6 Hydraulic system management (HSM)
The HSM controls the controlling elements of the gas boiler and passes the demand
signal in a suitable form to the boiler control while giving consideration to boiler-specific
functions.
Frost protection for the plant ensures protection when the outside temperature drops
below a certain level. When activated, the heating circuit pumps (Q1, Q2 and Q8, if
present) are directly activated so that the water in the heating circuit starts circulating.
Frost protection for the plant acts locally, that is, not on other heating zones of the
RVA46… These have their own frost protection.
In the case of DHW demand with absolute priority, that demand is given priority. If there
is no DHW priority, frost protection for the plant can be executed at the same time as
DHW heating.
Frost protection for the plant can be parameterized:
KonfigRg1.AnlagenFrost = 0: Frost protection for the plant deactivated
KonfigRg1.AnlagenFrost = 1: Frost protection for the plant activated
Frost protection for the plant uses the actual outside temperature. The type of response
depends on the outside temperature level.
If there is no outside temperature signal (LMU...-internal or external), frost protection for
the plant will be locked.
Outside temperature Impact on the heating circuits
TiAussen ≤ -5 °C Pumps on
-4 °C ≤ TiAussen ≤ 1.5 °C Pumps on for 10 minutes at 6-hour intervals
TiAussen > 1.5 °C Pumps off (if there is no other demand for heat)
In the temperature range -4...-5 °C, there can be different responses.
Decisive is the previous outside temperature level:
• If, before, the outside temperature was higher, the pumps will cycle in that range
• If, before, the outside temperature was lower, the pumps will remain activated in that
range
Frost protection
for the plant
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