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ERROR
CODE
CAUSE
ACTION
ER1
Full
sweep
value
less
than
90%
of
commissioned
value.
This
is
likely
due
to
debris
inside
of
the
valve.
Service
internals
of
mixing
valve
and
clean
or
replace
parts.
See
page
34
for
complete
service
instructions
ERPR
Inlet
pressure
differential
greater
than
10% Investigate
cause
of
pressure
differential
ERT3OS
Outlet temperature probe disconnected
from controller, not properly installed to
controller, or broken.
Check
wired
connection
to
controller
and
confirm
proper
configuration
(see
page
28
for
wiring
diagram).
Replace
probe
if
broken
ERT1OS
Inlet
hot
water
temperature
probe
disconnected
from
controller,
not
properly
installed
to
controller,
or
broken.
Check
wired
connection
to
controller
and
confirm
proper
configuration
(see
page
28
for
wiring
diagram).
Replace
probe
if
broken
ERT3+
Outlet
temperature
greater
than
5°F
above
set
point
Investigate
cause
ERT1+
Inlet
hot
water
temperature
is
above
185°F
Investigate
cause
of
hot
water
temperature
being
too
high.
Check
hot
water
source
ERT1
‐
Inlet
hot
water
temperature
is
below
set
point
and
is
too
cold
Investigate
cause
of
hot
water
temperature
being
too
low.
Check
hot
water
source
ERT3
‐
Outlet
temperature
greater
than
5°F
below
set
point
Investigate
cause
ERT4OS
Return
water
temperature
probe
disconnected
from
controller,
not
properly
installed
to
controller,
or
broken.
Check
wired
connection
to
controller
and
confirm
proper
configuration
(see
page
28
for
wiring
diagram).
Replace
probe
if
broken
ERT2OS
Inlet
cold
water
temperature
probe
disconnected
from
controller,
not
properly
installed
to
controller,
or
broken.
Check
wired
connection
to
controller
and
confirm
proper
configuration
(see
page
28
for
wiring
diagram).
Replace
probe
if
broken
ERT4+
Return
water
temperature
greater
than
set
point
temperature
Investigate
cause
ERT4
‐
Return
water
temperature
more
than
20°F
below
set
point
temperature
Investigate
cause
ERT2+
Cold
water
temperature
greater
than
set
point
temperature
Investigate
cause
24
Nucleus
Digitally
Controlled
Mixing
Valve
Error
Codes
Error
codes
are
displayed
on
LCD
screen
once
TTML
has
been
exceeded.
Errors
must
be
manually
cleared
by
pressing
ENTER
when
TTL
time
has
elapsed
and
the
error
condition
has
not
been
corrected.
Error
codes
below
are
listed
in
order
of
importance
to
valve
and
system
performance.