SERVICING
Alternately, the system CFM can be determined by operating 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 chart below.
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 measured 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 pressure at a particular CFM will be less.
TEMPERATURE RISE (F°) @ 240V
CFM | 4.8 | 7.2 | 9.6 | 14.4 | 19.2 | 24.0 | 28.8 | |
KW | KW | KW | KW | KW | KW | KW | ||
| ||||||||
|
|
|
|
|
|
|
| |
600 | 25 | 38 | 51 | - | - | - | - | |
700 | 22 | 33 | 43 | - | - | - | - | |
800 | 19 | 29 | 38 | 57 | - | - | - | |
900 | 17 | 26 | 34 | 51 | - | - | - | |
1000 | 15 | 23 | 30 | 46 | - | - | - | |
1100 | 14 | 21 | 27 | 41 | 55 | - | - | |
1200 | 13 | 19 | 25 | 38 | 50 | - | - | |
1300 | 12 | 18 | 23 | 35 | 46 | - | - | |
1400 | 11 | 16 | 22 | 32 | 43 | 54 | 65 | |
1500 | 10 | 15 | 20 | 30 | 40 | 50 | 60 | |
1600 | 9 | 14 | 19 | 28 | 38 | 47 | 57 | |
1700 | 9 | 14 | 18 | 27 | 36 | 44 | 53 | |
1800 | 8 | 13 | 17 | 25 | 34 | 42 | 50 | |
1900 | 8 | 12 | 16 | 24 | 32 | 40 | 48 | |
2000 | 8 | 12 | 15 | 23 | 30 | 38 | 45 | |
2100 | 7 | 11 | 14 | 22 | 29 | 36 | 43 | |
2200 | 7 | 11 | 14 | 21 | 27 | 34 | 41 | |
2300 | 7 | 10 | 13 | 20 | 26 | 33 | 39 |
ELECTRIC HEATER CAPACITY BTUH
HTR | 3.0 | 4.7 | 6.0 | 7.0 | 9.5 | 14.2 | 19.5 | 21.0 |
KW | KW | KW | KW | KW | KW | KW | KW | KW |
BTUH | 10200 | 16200 | 20400 | 23800 | 32400 | 48600 | 66500 | 71600 |
|
|
|
|
|
|
|
|
|
FORMULAS:
Heating Output = KW x 3413 x Corr. Factor
Actual CFM = CFM (from table) x Corr. Factor
BTUH = KW x 3413
BTUH = CFM x 1.08 x Temperature Rise (T)
CFM = KW x 3413 1.08 x T
T = BTUH
CFM x 1.08
S-61A CHECKING HEATER LIMIT CONTROL(S)
Each individual heater element is protected with a limit control device connected in series with each element to prevent overheating of components in case of low airflow. This limit control will open its circuit at approximately 150°F.
HIGH VOLTAGE!
Disconnect ALL power before servicing or installing. Multiple power sources may be present. Failure to do so may cause property damage, personal injury or death.
1.Remove the wiring from the control terminals.
2.Using an ohmmeter, test for continuity across the nor- mally closed contacts. No reading indicates the control is open - replace if necessary.
IF FOUND OPEN - REPLACE - DO NOT WIRE AROUND.
S-61B CHECKING HEATER FUSE LINK (OPTIONAL ELECTRIC HEATERS)
Each individual heater element is protected with a one time fuse link which is connected in series with the element. The fuse link will open at approximately 333°.
WARNING
Disconnect ALL power before servicing.
1.Remove heater element assembly so as to expose fuse link.
59
