Dunkirk Excelsior EXB Series - Manual (Page 39)

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Figure 34 - Limit
16 - OPERATING THE BOILER - SYSTEM START-UP
16.1 Setting The Limit Control
Setting can be verified using TEST/SETTINGS button.
See Page 41.
16.2 Setting High Limit
To adjust, turn HI TEMP dial A until desired setting is
displayed. See Figure 34. Overall range of High limit setting
is from 100°F to 220°F (82° C to 104° C). High limit
(HL) on limit control is factory set at 190°F. Temperature
setting may be varied to suit requirements of installation.
Differentials are automatic and will vary based on control
settings and boiler temperature.
16.3 Setting Low Limit
• Low limit is designed to maintain temperature in boilers
equipped with tankless coils used for domestic hot
water. Low limit is factory set to OFF.
• For cold start operation, low limit must be turned to
OFF.
16.4 Setting Economy Feature (See Figure 35)
• Economy feature is factory set for 1 zone heating
system. To adjust, turn ECONOMY dial D until number
displayed equals number of heating zones.
• Do not include indirect water heaters in number of
heating zones.
• Economy feature conserves fuel by reducing boiler
temperature. If heating system is unable to supply
needed heat to house, ECONOMY dial should be turned
to lower setting. (example: in a three zone house, turn
dial to 2 or 1).
• Conversely, if boiler provides adequate heat, added
fuel savings can be achieved by selecting higher setting
(example: 4 or 5).
• If heating and indirect water heater signals were not
separated when wiring the control, Economy feature
should be turned off to ensure the boiler supplies
adequate temperature to heat indirect tank.
16.5 Setting Zone/Indirect Switch
When installing with indirect water heater, zone/indirect
switch must be set in the I position, calls to ZC-ZR will
bypass thermal targeting feature and allow boiler to fire to
high limit setting to heat indirect tank.
Indirect signal must be separate from all heating zone
signals.
If you choose not to separate indirect signal from heating
zones, turn off economy feature to ensure boiler supplies
adequate temperature to indirect tank.
Figure 35 - Setting Economy Feature
SETTING
OFF
Disables economy function. Will allow boiler to
fire until hi-limit temp is reached and re-fire
with a 10° subtractive differential.
LO
Provides lowest level of fuel savings. Use this
setting only if the house does not stay warm at
higher settings.
1 Recommended setting for single zone systems.
2 Recommended setting for Two zone systems.
3 Recommended setting for Three zone systems.
4 Recommended setting for Four zone systems.
5 Recommended setting for Five zone systems.
HI Provides highest level of fuel savings.