48
17.
CH and DHW SERVICE SETTINGS
17.1
CH activation temperature
This parameter specifies the temperature
at which the central heating pump is
activated.
After
reaching
the
temperature equal to the
CH activation
temp.
parameter, the central heating
pump is activated. This protects the
boiler against retting caused by its being
cooled down by hot water returning from
the system.
Disabling the CH pump on its
own
does
not
guarantee
protecting the boiler against
retting,
and
the
resulting
corrosion of the boiler. Use
additional automatics, e.g. a
four-way valve.
17.2
CH pump standstill during
HUW filling
Prolonged filling of the HUW tank when
HUW priority is enabled can cause
excessive cooling of the CH system,
because with these settings, the CH
pump is disabled.
The parameter
CH standstill when filling
HUW
prevents this by enabling periodic
activation of the CH pump during filling
of the HUW tank. After this time, the CH
pump will be activated for constant, pre-
programmed time of 30 s.
17.3
Minimum HUW temperature
This parameter allows to prevent the
user from setting too low a preset
temperature of HUW.
17.4
Maximum HUW temperature
This parameter specifies the maximum
temperature of heating the HUW tank
when dropping excessive heat from the
boiler
during
emergencies.
This
parameter is of great significance, as
setting it at too high can put the users at
risk of being scalded with the utility
water. Too low a value thereof will make
it impossible to carry excessive heat
away to the HUW tank if the boiler
overheats.
When designing the hot utility
water system, it is necessary
to provide for the possibility of
regulator failure. As a result of
the regulator failure, the water
in the hot utility water tank can
overheat to a dangerous
temperature, putting the users
at risk of being scalded.
ALWAYS APPLY ADDITIONAL
SAFEGUARD IN THE FORM
OF
THERMOSTATIC
VALVES.
17.5
Increase in boiler temperature
from HUW, mixer circuit and
buffer status
This parameter specifies the number of
degrees by which the preset boiler
temperature can be increased in order to
fill the HUW tank, supply buffer and
mixer circuit. The temperature is
increased only if necessary. If the preset
boiler temperature is sufficient, the
regulator will not change it due to
necessity of filling the HUW tank,
supplying buffer, or mixer circuit.
Increasing the preset boiler
temperature during filling of the
HUW tank is signalled by letter
“C” displayed in the main
window.
17.6
Extending
HUW
pump
operation
After filling the HUW tank and disabling
the HUW pump, there is often a problem
of the boiler overheating. It occurs if the
preset domestic hot water temperature
is higher than the preset boiler
temperature. In particular, this problem
occurs in the HUW pump mode:
“SUMMER”, when the CH pump is
disabled. In order to cool the boiler
down, operation of the HUW pump can
be extended by the time of
HUW
operation extend
.
Summary of Contents for ZAB-14
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