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Building Technologies
Modular Heating Controller RMH760B
CE1P3133en
HVAC Products
5 General functions, fundamentals
05.02.2007
The sequence of frost protection for the plant is as follows:
-2
OFF
0
1
2
3
4
-3
-4
-5
-6
-1
ON/OFF
ON
1 K
TO
TO
OFF
TO
ON
31
31D
09
TO
<–5 °C (TO
ON
)
-4…+2 °C
>2 °C (TO
OFF
)
Pump
Continuously
on
On for 10 minutes every 6 hours
Continuously off
Status
ON
ON / OFF
OFF
Adjustable are the following temperatures:
•
TO
ON
: Outside temperature at which “Frost protection for the plant“ switches the
pump continuously on (frost protection for the plant continuously ON)
•
TO
OFF
: Outside temperature at which "Frost protection for the plant” lets the pump
cycle (frost protection for the plant cycling ON)
In the event the outside sensor becomes faulty, frost protection for the plant will con-
tinue to operate with a constant backup value of 0 °C outside temperature.
5.4
Pump overrun and mixing valve overrun
For all pumps (exception: circulating pump) and all mixing valves, overtemperature
protection can become active. Overtemperature protection always becomes active after
the burner has been shut down. To ensure that the heat consumers still draw heat for a
minimum period of time, an overrun time is enforced on the heat consumers that were
switched off within the last minute. During that overrun time, the pumps and mixing
valves continue to operate; the pumps continue to run and the mixing valves maintain
the “old” setpoint.
The duration of the overrun time is dependent on the type of heat source used and can
therefore be set on the boiler.
Main menu > Commissioning > Settings > …
or
Main menu > Settings > Boiler > Limitations
Operating line
Range
Factory setting
Consumer overrun time
0…60 min
6 min
In order to also ensure overrun on plant with no system-internal heat exchanger, over-
run can also be set on the heat consumers.
Main menu > Settings > Protective functions
Operating line
Range
Factory setting
Consumer overrun time
0…60 min
6 min
This setting can only be made on plant with
no
boiler.
Every heat consumer has a minimum overrun time of 60 seconds.
With DHW heating, it is to be noted that discharging protection is given priority over
pump overrun.
In the case of DHW heating with primary and secondary pump, the secondary pump
operates for an additional pump overrun time to prevent the external heat exchanger
from reaching excessive temperatures.
Main menu > Settings > DHW > Controller primary circuit
Operating line
Range
Factory setting
Overrun time secondary pump
0…60 min
1 min
Sequence of functions
Faulty outside sensor