EMI CAC_36, Инструкция по установке, эксплуатации и обслуживанию

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39 Cassette Air Handler
WALL THERmOSTAT CONTROL – mOdELS CAHA ANd CACA
TROUBLESHOOTINg pROCEdURE
Continued
COOLINg ONLY UNITS
Cooling only units, require an 18 AWG low
volt interconnecting wires between the in-
door and outdoor units. Also, an intercon
-
nect wire is required between the indoor
unit and wall thermostat. Refer to low V
olt
interconnect diagram
Figures #12 or #13
for remote thermostat connection.
NOTE:
“W” is required for units with electric heat only.
“C” may not be needed on some thermostats.
The wall mounted thermostat will switch on
and off the outdoor unit through the black “Y”
and yellow “Y1” wires. When the thermostat
is calling for cooling, 24 Vac can be measured
across terminals “Y” and “C” of the outdoor
unit or “Y1” and “C” of the Cassette.
The indoor unit contains an electronic anti-
short cycle timer feature (ASCT) that will
prevent the outdoor unit from short cycling.
After the thermostat is satisfied there will
be a three minute delay before the outdoor
unit is allowed to re-start.
While the wall thermostat is calling for cool-
ing and the ASCT delay has elapsed, 24
Vac can be measured between terminals
Y” and “C” of the outdoor unit or “Y1” and
“C” of the Cassette.
for optional
wall thermostat operation, 24
Vac can also be measured across low V
olt
terminals “G” and “C” of the Cassette.
HEAT pUMp UNITS
Heat pump units, require an 18 AWG low
volt interconnecting wire between the in-
door and outdoor units. Also, an intercon
-
nect wire is required between the indoor
unit and wall thermostat. Refer to low V
olt
interconnect diagram
Figures #12 or #13
for remote thermostat connection.
The wall mounted thermostat will switch on
and off the outdoor unit through the black
“Y” and yellow “Y1” wires. When the ther
-
mostat is calling for cooling or heating, 24
Vac can be measured across terminals “Y”
and “C” of the outdoor unit or “Y1” and “C”
of the Cassette.
EMI heat pump systems utilize a revers
-
ing valve is that is energized in the cool
-
ing mode. Heat pump units will operate
the compressor in heating mode while
the reversing valve is de-energized. The
reversing valve signal is provided through
the orange “O” low V
olt wire of the thermo-
stat. It should remain energized constantly
as long as the thermostat’s system switch
remains in Cooling Mode.
To check for 24
Vac reversing valve voltage at the outdoor
unit, place a voltmeter across the brown “C”
and orange “O” wires while in the
Cooling
Mode.
The meter should read 24 Vac
NOTE:
“O” is required for heat pump operation. The
reversing valve is energized in cooling.
“W” is required for units with electric heat only.
“C” may not be needed on some thermostats.
The indoor unit contains an electronic anti-
short cycle timer feature (ASCT) that will
prevent the outdoor condenser from short
cycling. After the thermostat is satisfied
there will be a three (3) minute delay before
the condenser is allowed to re-start.
While the wall thermostat is calling for cool-
ing or heating and the ASCT delay has
elapsed, 24 Vac can be measured between
terminals “Y” and “C” of the outdoor unit or
“Y1” and “C” of the Cassette.
for optional
wall thermostat operation, 24
Vac can also be measured across the Cas
-
sette’s low Volt terminals “G” and “C” for the
fan signal.