EMI CAC_36, Инструкция по установке, эксплуатации и обслуживанию

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Cassette Air Handler
40
ELECTRIC HEAT
(Optional)
Units with electric heat utilize a control relay
located on the circuit board in the control
box. When the wall thermostat is calling for
electric heat the relay will energize.
To check for electric heat operation, place
the wall thermostat in electric heat Mode
with the setpoint temperature above room
temperature. Then place a clamp-on type
ammeter on one leg of the incoming power
supply. When working correctly the amp
reading should correspond with the values
in the table below.
The following current values apply when
the unit is connected to a 230 Vac power
supply. These values include fan motor cur
-
rent. If the supply voltage is different, this
will affect the amp draw of the heater.
5kw = 22.7 A 3kw = 13.6 A 1.5kw = 6.9 A
The electric heat relay can also be veri
-
fied by placing a voltmeter across the high
volt relay output terminal and the incoming
power L2 terminal. If working correctly the
reading should be the same as measured
across the incoming power supply.
As a safety feature, an auto resetting limit
switch located on the heater assembly that
will interrupt power to the heater if an over-
temperature condition occurs. Each limit
switch is also equipped with a one-time
fuse link. Should electric heat temperatures
rise above the auto resetting limit switch,
the non-resetting, one-time fuse link will
open and the heater will remain off. If this
occurs the limit switch assembly must be
replaced. Contact EMI technical service for
a replacement.
To check if the fuse link has failed will require
an Ohm reading across the limit switch.
mAkE SURE TO fULLy dISCONNECT
ALL pOWER TO BOTH THE INdOOR
CASSETTE ANd OUTdOOR UNIT.
After disconnecting all power to the unit,
WALL THERmOSTAT CONTROL – mOdELS CAHA ANd CACA
Continued
TROUBLESHOOTINg pROCEdURE
Continued
disconnect the wires from the fuse link.
Then with an ohmmeter, check the conti
-
nuity across the fuse link. If the fuse link is
open it must be replaced.
For optional wall thermostat operation, 24 Vac
can also be measured across the Cassettes
low volt terminals “G” and “C” for the fan signal
and “W” and “C” for electric heat signal.
TWO STAgE HEATINg
Two stage heating combines heat pump
and electric heat operation. Heat pump
units require an 18 AWg low volt intercon-
necting wire between the indoor unit and
the condenser. Also, an interconnect wire
is required between the indoor unit and wall
thermostat. Refer to low volt interconnect
diagram
Figures #12 or #13 for remote
thermostat connection.
After connecting a two stage heating ther-
mostat to the unit, place the system switch
in heat Mode
. Adjust the setpoint tempera
-
ture above the room temperature so that
first stage heating is activated. The com
-
pressor and fan motors will start and heat
-
ing will begin. Heating will continue so long
as the setpoint temperature remains above
room temperature.
To check for a low volt signal, place a volt
-
meter across terminals “Y” and “C” of the
outdoor unit or “Y1” and “C” of the Cas
-
sette. When working correctly, there should
be a reading of 24 Vac.
Next, place the setpoint further above room
temperature to activate second stage heat
-
ing. Electric heat will energize (along with
the compressor) when the deviation be
-
tween room temperature and setpoint tem
-
perature is high enough to call for second
stage heating. (See the thermostat owner’s
manual for this feature). Heating will con-
tinue so long as the setpoint temperature is
above the room temperature and the ther
-
mostat is calling for second stage heating.