RLC-
VU006A-E
Interconnecting Wirin
hilled Water Pump
ontrol
NOTICE:
quipment Dama
e
If the microprocessor calls for a pump to start and
water does not fl ow, the evaporator may be damaged
catastrophically. It is the responsibility of the installin
contractor and/or the customer to ensure that a pump
will always be running when called upon by the chiller
c
ntr
ls.
An evaporator water pump output relay closes when
the chiller is given a signal to go into the
uto mode
o
operation
rom any source. The contact is opened to
turn off the pump in the event of most machine level
dia
nostics to prevent the build up of pump heat.
The relay output is required to operate the Evaporator
Water Pum
(EWP) contactor. Contacts should be
compatible with 115/240 VAC control circuit. Normally,
the EWP rela
follows the AUTO mode of the chiller.
henever the chiller has no diagnostics and is in the
AUTO mode, re
ardless of where the auto command
is coming
rom, the normally open relay is energized.
When the chiller exits the AUT
mode, the rela
is timed
to open in an adjustable (usin
TU) 0 to 30 minutes.
The non-AUT
modes in which the pump is stopped,
include Reset,
to
, External
to
, Remote Dis
lay
to
,
topped by Tracer,
tart Inhibited by Low Ambient Temp,
and Ice Buildin
complete.
Table 5. Pump Relay Operation
Chiller Mod
ela
O
eratio
t
nst
nt cl
se
ce Buildin
nst
nt cl
se
Tr
cer
verri
e Cl
se
to
Timed O
en
ce Com
lete
nstant
en
ia
nostics
nstant
en
When going from Stop to Auto, the EWP relay is
energized immediately. If evaporator water fl ow is not
established in 20 minutes
for normal transition
or 4
minutes, 15 seconds (for
um
commanded ON due to
an override safety), the UC800 de-ener
izes the EWP
relay and generates a non-latching diagnostic. I
ow
returns (e.g. someone else is controlling the pump),
the diagnostic is cleared, the EWP is re-energized, and
norma
contro
resume
.
f evaporator water fl ow is lost once it had been
established, the EWP relay remains energized and a
non-latching diagnostic is generated. If fl ow returns, the
iagnostic is cleared and the chiller returns to normal
o
eration.
n
eneral, when there is either a non-latchin
or latchin
ia
nostic, the EWP relay is turned o
as thou
h there
as a zero time delay. Exce
tions whereby the relay
continues to
e ener
ized occur with:
ow
hilled Water Temp. diagnosti
(non-latching)
unless also accompanied by an Evap Leaving Water
Temperature Sensor Diagnostic
r
oss o
Evaporator Water Flow diagnosti
non-
latching) and the unit is in the AUTO mode, after
nitially havin
proven evaporator water
ow.
ro
rammable
elay
pro
rammable relay concept provides for enunciation
o
certain events or states o
the chiller
selected
rom a
list of likely needs, while only using four physical output
elays, as shown in the fi eld wirin
dia
ram. The four
elays are provided (
enerally with a Quad Relay Output
LID) as part of the Pro
rammable Relay Option. The
elay’s contacts are isolated Form C
SPDT
, suitable
for use with 120 VAC circuits drawing up to 2.8 amps
nductive, 7.2 amps resistive, or 1/3 HP and for 240 VAC
circuits
rawin
up to 0.5 amp resistive.
The list of events/states that can be assi
ned to the
rogrammable relays can be
ound in Table 6. The relay
ill be ener
ized when the event/state occurs.
nstallation El
ctrical