7
During these “soft” lockout conditions the burner function
is blocked for DHW as well as CH request for heat. Only
the CH circulator will respond to a request for heat.
Both error codes will reset automatically when the error
condition is corrected.
During any DHW error condition the Prestige will
continue to maintain normal CH circulator oper-
ation on a CH request for heat, but will block the
burner function for a CH request for heat. The
Prestige will block the burner and DHW circula-
tor operation on a DHW request for heat until the
error condition is corrected.
DHW NTC SENSOR DIFFERENTIAL
The MCBA module has 2 differential settings for the
burner operation when using a NTC for DHW applica-
tions.
The first dif
ferential setting is Parameter 26
“Detection ON”. This parameter sets the DHW storage
temperature low limit. The burner operation will respond
when the DHW storage temperature drops below the
Parameter 1 setting minus the Parameter 26 setting.
A minimum “Detection ON” parameter setting will create
a quick burner operation response to any domestic
water draws from the storage tank. In contrast, a maxi-
mum “Detection ON” setting will result in a delay
response to domestic draws.
NOTICE
The “Detection ON” setting of Parameter 26
greatly affects the production of domestic hot
water. A minimum setting of Parameter 26 could
result in rapid responses to a DHW request for
h
eat resulting in a potential scald hazard. It is
strongly recommended that the installer utilizes
a thermostatic mixing valve on the hot water out-
let of the DHW storage tank. Failure to comply
could result in severe personal injury, death or
substantial property damage.
Parameter Adjustments
To adjust DHW NTC sensor differential “DETECTION
ON” value follow the steps given in the Program Access
Section on page 2 until the display shows
P_26
.
Release the STEP button and the display should show
the factory setting. Use the + or - to adjust to the revised
setting and press STORE to save the setting. The dis-
play setting will flash when the setting is stored within the
MCBA control.
The second differential setting is Parameter 27
“Detection OFF”. This parameter sets the DHW storage
temperature high limit. The burner operation will cease
when the DHW storage temperature rises above the
Parameter 1 setting plus Parameter 27 setting.
A maximum “Detection OFF” parameter setting will result
in an extended burner firing cycle when responding to
any domestic water draws from the storage tank. This
extended burner firing cycle could result in a final stor-
age temperature of the domestic hot water that is higher
than the desired storage temperature setting.
D
ANGER
P_26 02ºF 02ºF 54ºF
Error Code Reason / Correction
b_33
The NTC sensor is “short circuited".
T
his will also occur if the sensor would
detect a false temperature reading
above 260ºF. Check wiring of the NTC
sensor for proper connections.
b_38
The NTC sensor is open. This will also
occur if the sensor would detect a false
temperature reading of -32ºF. Check
and ensure NTC sensor is properly
wired and connect to the proper
terminals on the Prestige low voltage
terminal strip.
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