ACCESSORIES
61
CHECKING HEATER LIMIT CONTROL(S) (OPTIONAL
ELECTRIC HEATERS)
Each individual heater element is protected with an auto-
matic rest limit control connected in series with each ele-
ment to prevent overheating of components in case of low
airflow. This limit control will open its circuit at approximately
150°F. to 160°F and close at approximately 110°F.
WARNING
Disconnect power supply before servicing.
1. Remove the wiring from the control terminals.
2. Using an ohmmeter test for continuity across the
normally closed contacts. No reading indicates the
control is open - replace if necessary. Make sure the
limits are cool before testing.
IF FOUND OPEN - REPLACE - DO NOT WIRE AROUND.
CHECKING HEATER ELEMENTS
Optional electric heaters may be added, in the quantities
shown in the spec sheet for each model unit, to provide
electric resistance heating. Under no condition shall more
heaters than the quantity shown be installed.
WARNING
HIGH VOLTAGE
Disconnect ALL power before servicing or in-
stalling this unit. Multiple power sources may
be present. Failure to do so may cause proper-
ty damage, personal injury or death.
1. Disassemble and remove the heating element(s).
2. Visually inspect the heater assembly for any breaks in
the wire or broken insulators.
3. Using an ohmmeter, test the element for continuity -
no reading indicates the element is open. Replace as
necessary.
ELECTRIC HEATER (OPTIONAL ITEM)
Optional electric heaters may be added, in the quantities
shown in the specifications section, to provide electric resis
-
tance heating. Under no condition shall more heaters than
the quantity shown be installed.
The low voltage circuit in the air handler is factory wired and
terminates at the location provided for the electric heat-
er(s). A minimum of field wiring is required to complete the
installation.
Other components such as a Heating / Cooling Thermostat
and Outdoor Thermostats are available to complete the
installation.
The system CFM can be determined by measuring the
static pressure external to the unit. The installation manual
supplied with the blower coil, or the blower performance
table in the service manual, shows the CFM for the static
measured.
Alternately, the system CFM can be determined by operat-
ing the electric heaters and indoor blower WITHOUT having
the compressor in operation. Measure the temperature rise
as close to the blower inlet and outlet as possible.
If other than a 240V power supply is used, refer to the
BTUH CAPACITY CORRECTION FACTOR in the following
chart.
BTUH CAPACITY CORRECTION FACTOR
SUPPLY VOLTAGE
250
230
220
208
MULTIPLICATION FACTOR
1.08
.92
.84
.75
EXAMPLE:
Five (5) heaters provide 24.0 KW at the rated
240V. Our actual measured voltage is 220V, and our mea-
sured temperature rise is 42°F. Find the actual CFM:
Answer:
24.0KW, 42°F Rise, 240 V = 1800 CFM from the
TEMPERATURE RISE
chart on the right.
Heating output at 220 V = 24.0KW x 3.413 x .84 = 68.8
MBH.
Actual CFM = 1800 x .84 Corr. Factor = 1400 CFM.
NOTE:
The temperature rise table is for sea level installa-
tions. The temperature rise at a particular KW and CFM will
be greater at high altitudes, while the external static pres-
sure at a particular CFM will be less.
3
5
6
8
10
15 19/20 25
800
12
19
23
31
37
1000
9
15
19
25
30
44
1200
8
12
15
21
25
37
49
62
1400
7
11
13
18
21
32
42
53
1600
6
9
12
15
19
28
37
46
1800
5
8
10
14
16
25
33
41
2000
5
7
9
12
15
22
30
37
CFM
HEAT KIT NOMINAL kW
230/1/60 SUPPLY VOLTAGE - TEMP. RISE °F
3
5
6
8
10
15 19/20 25
800
11
18
22
30
35
1000
9
14
18
24
28
42
1200
7
12
15
20
24
35
47
59
1400
6
10
13
17
20
30
40
51
1600
6
9
11
15
18
27
35
44
1800
5
8
10
13
16
24
31
39
2000
4
7
9
12
14
21
28
35
CFM
HEAT KIT NOMINAL kW
220/1/60 SUPPLY VOLTAGE - TEMP. RISE °F
