Step 3-Heat Exchanger and Flue PipeOrdinarily, it is not necessary to clean heat exchanger or flue pipeevery year, but it is necessary to have your service techniciancheck unit before each heating season to determine whethercleaning or replacement of parts is required.If cleaning is necessary, the following steps should be performed:1. Turn off all oil and electrical supplies upstream of furnace.If furnace has been in operation, some surfaces may be hot.Allow time for unit to cool down personal injury will result.2. Disconnect flue pipe.3. Remove flue collar panel located in rear part of furnace.4. Remove flue silencer from secondary heat exchanger.5. Disconnect oil line and remove oil burner from furnace.6. Clean primary and secondary heat exchangers with a stiffbrush and vacuum cleaner.7. Before reassembly, heat exchanger/combustion chambershould be inspected to determine if replacement is required.8. After cleaning, replace flue silencer, flue collar, and oilburner.9. Readjust burner for proper operation.Step 4-Blower RemovalTo remove blower from furnace:1. Turn off all oil and electrical supplies upstream of furnace.2. Remove blower access door.3. Remove air filters.4. Remove blower retaining wing nuts.5. Slide blower on rails toward rear of unit.6. Reverse items 1 through 5 to reinstall blower. Refer to wiringdiagram (Fig. 3 or 4) of these instructions or diagram locatedon inside of blower door to properly rewire unit.Table 12-Airflow Data (CFM)UNITSIZEBLOWERSPEEDEXTERNAL STATIC PRESSURE IN. WC0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9105-12High 1425 1350 1305 1250 1170 1030 925 805Med-High 1130 1045 1000 950 885 820 745 670Med-Low 840 810 770 740 685 635 580 500Low 725 730 740 745 730 715 690 665120-20High 2080 2041 1965 1864 1702 1576 1474 1336Med-High 1892 1859 1770 1675 1550 1449 1330 1217Med-Low 1556 1475 1394 1318 1211 1134 1051 938Low 1221 1164 1081 998 926 855 782 653NOTES:1. Airflow values in cubic ft per minute (CFM) rounded to nearest 5 CFM.2. Data taken with filters in place.11