Crown TWZ065, Installation Instructions Manual

Page: 33 / 48

31
  
1 sec.
1 sec.
1 sec.
FIGurE 12.3: tYPIcal OPEratInG MODE DIsPlaY (BOIlEr tEMP sHOWn)
taBlE 12.2: status cODEs
Status # Description Meaning
1 Standby
No call for heat or DHW
OR
Call for heat present , but boiler is in thermal purge (See
PP
on page 11)
OR
Call for heat/DHW present but boiler temperature is above set point (
SP
) setting.
8 Burner Demand
The burner is running
OR
The burner is off due to an open limit (such as an external high limit or LWCO)
OR
The burner is being prevented from firing by its primary control.
17 Self test Boiler was just energized and control is running a self check.
NOTE
In operating mode, holding either the ↑
or
↓ button while viewing a given parameter will keep
the display on the actual reading. For example, pressing
↑
while reading boiler temperature as
shown in Figure 12.3 will keep the display on 180 for as long as this button is held. This makes
it easier to view readings “live” if they are changing rapidly
taBlE 12.4: OPEratInG MODE ParaMEtErs
Parameter # Description Meaning
bt Boiler Temperature Current boiler water temperature measured by the control’s sensor.
SP Boiler Water Set Point Current target temperature (always the same as the high limit setting)
HL High Limit Set Point
Boiler will stop firing if boiler water temperature exceeds this value (Circulator/s
will continue to operate)
HdF High Limit Differential If high limit setting is reached, boiler water temperature will need to drop by this
amount before boiler will again fire during the same call for heat.
LL
Low Limit Set Point
(Warm Strat Control)
If the boiler water temperature falls below this point less the differential the
circulator is forced off and the burner is turned on. If the boiler water tempera -
ture rises above this point the burner is turned off and the circulator is enabled to
respond to a call for heat.
LdF
Low Limit Differential
(Warm Start Control)
This is the number of degrees the boiler water temperature must decrease below
the Low Limit Set Point before the burner is turned on and the water flow
through the boiler is turned off.
hr Heat Request Status Shown as either ON or OFF. Indicates whether there is a call for heat.
dh
DHW Request Status
Shown as either ON or OFF. Indicates whether there is a demand from the ZR
terminal for domestic hot water (DHW). Note that if the dh zone on the L7248L
or the L7224A is used as a second heating zone (see Table 12.5), this parameter
will be shown as OFF and
hr
will be shown as ON when a demand from ZR is
present.