2-7
BOILER SYSTEMS AND OPERATION
SL 30-175, SL 45-260 MODULATING GAS BOILERS
initial cycle, the clashing loads will switch back and forth after further 10 min.
intervals pending satisfaction of one or both loads.
to cause repeated unequal run times (for example, constant 35 vs 5 min. runs) it
is necessary to integrate an external load removing relay or timer on one of the
heat calls (contact the Factory for details).
2.6.2 Load Pairing
With software versions 3.10.0 and higher, the controller allows two loads of
compatible temperature settings to be run together. see iBC technical note:
Load Pairing
for further details
.
2.6.3 Reset Heating
the boiler offers outdoor reset control as standard equipment; this coordinates
the control of boiler supply water temperature for space heating with the outdoor
temperature. Outdoor Reset offers enhanced comfort and efficiency by using
variable water temperatures to compensate for the differing rates of heat loss that
a building faces as outdoor temperature changes. at any outdoor temperature
above the coldest day expected
, it automatically uses lower heating temperatures
than would otherwise be used. This saves energy without sacrificing comfort.
When applied within a condensing boiler, outdoor reset offers direct and
significant combustion efficiency benefits by allowing generally lower circulating
water temperature. this provides cooler return water to the boiler, promoting
more condensation (= energy capture).
Contacts are provided for connection of an outdoor sensor (a
tekmar 070
or
similar sensor is shipped with each boiler) to be placed in an appropriate outdoor
position. The temperature management algorithm flexes the boiler supply
temperature according to characterized heating curves that are automatically
called up through the load declaration process. Curves are provided for each
of the radiation terminal types offered - e.g. high or low mass radiant floor, air
handler, finned tube baseboards etc.
in an “open loop” reset system, a room or zone thermostat is used to send a call
for heat over a 24VaC lead; this opens the respective zone valve, and signals
Figure 31: Outdoor reset curves
NOTE
US law effective Sept 2012
requires residential heating
boilers under 300,000 btu/
hr to be equipped with
Automatic Means of boiler
water temperature adjustment
in relation to heat demand.
This boiler offers such control
but also a means to override
it. See the inside back cover
of this Manual for a message
in respect of the use of such
override.
Содержание SL 30-175
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