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greater than the value of Parameter 4 (t1 top). there
is no concern that temperature boost would supply
water too hot for low-temperature systems, such as
slab-type radiant heating. On hybrid systems, with
finned tube radiation and radiant slab, provide additional
low temperature protection for the radiant portion of the
system, because Parameter 4 (t1 top) is likely to be
set higher than on a radiant-only system.
IMPORTANT: Many slab-type radiant systems
won't require boost. This function can be dis-
abled with a parameter 11 setting of "0."
Boost operation
1.
in outdoor reset operation (outdoor sensor connected),
the boiler control automatically increases the target out-
let water temperature if a call for heat exceeds a time
equal to Parameter 11 (factory default of 30 minutes).
2.
at each interval of Parameter 11 of a continuous call for
heat, the control module increases the target tempera-
ture by 18° F. See Figure #3.
3.
the control module will continue increasing target
temperature until it reaches the value set in Parameter
4 (t1 top).
4.
When the call for heat ends while target temperature is
"boosted," the target temperature drops about 2° F for
Temperature Boost Operation (typical): in this example, the boiler is operating in outdoor reset mode with a calculated setpoint tem-
perature of 130°F. the call for heat has lasted more than 10 minutes (value of Parameter 11) and supply temperature boost has occured.
III - pARAMETER EXpLANATIONS
PARAMETER 11 (automatic supply temperature booster operation)
each minute the thermostat is open.
5.
Range: 1-30 minutes.
6.
Factory default: 30 minutes.
7.
deactivate automatic temperature boost by setting to
"0."
MAXIMUM FAN SpEED
Fan speed must be set within the limits sup-
plied by the factory (See the "Default Param-
eters table" in Section II). Setting limits above
or below these factory defaults would increase
or decrease boiler firing rate beyond the ac-
ceptable limit, resulting in potential for severe
personal injury, death, or substantial property
damage.
•
Parameters 13 and 15 can be set to limit the maximum
boiler firing rate. Boiler firing rate is proportional to the
fan speed, so reducing the maximum fan speed reduc-
es maximum input.
•
Reducing maximum fan speed will be helpful for sys-
tems on which the boiler is oversized for either space
heating or dHW, or both.
•
maximum fan speed can be set separately for space
Figure #3
8
WARNING
!
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