Shut gas and power off to the unit, close the system off and drain the heater. Remove the draft diverter. Remove the access panel and jacket top. Lift flue collector off. Remove “V” baffles over tube(s) to be replaced. If no pipe unions have been provided, use the header as a union, remove the flange nuts off the inlet- outlet header, break gas connection and slide heater away from piping to allow room to work. Pull wedge clips out of control wells and remove sensing bulbs. Remove flange nuts of the return header and remove header. Lift heat exchanger straight up and out.
Inspect “O” ring seals at this time. Unless severed, they are reusable. The tube may be cut out with a hacksaw or hammer and chisel adjacent to both tube sheets, leaving studs in the tube sheets. Then proceed to collapse studs in the tube sheets with a chisel or screwdriver. Use caution not to cut into the tube sheet. Replacement tubes will have the fins stripped off longer on one end. The long end is inserted into the opening of the tube sheet first; then the short end is fitted through the opposite tube sheet. If the tube ends become dented or bent, straighten at least (4) inches back from the tube and by means of a tapered punch.
Insert tube roller into tube opening up to stop against tube, then push center rod in until roller is tight. Be careful to keep replacement tube squared up 1/8” outside each tube sheet. A loose tube will sometimes pull toward the roller. Attach drill motor to tube roller, holding it straight and level. Proceed to expand tube until the tool begins to grab. At this point, 1/2” to 1” should be expose on the tool shank. Reverse drill motor or wrench out by hand. Care should be exercised to avoid applying excessive torque during rolling operation and to avoid thinning out any part of the tube wall excessively over 015’. Use same procedure at the opposite end of the tube.
Apply line pressure test, and
DESOOTINGPROCEDURE
CAUTION: SOOT IS COMBUSTIBLE. EXERCISE EXTREME CARE.
Soot will clog areas between fins and cause eventual tube failure. Any sign of soot at the base of the burners or around the outer jacket indicates a need for cleaning.
1.Remove top and flue collector from cabinet.
2.Remove “V” baffles from heat exchanger.
3.Remove burner drawer. (See burner tray removal).
4.Take garden hose and wash heat exchanger, making sure soot is removed from between fins. (Avoid excessive water against refractory).
5.
NOTE: In extreme cases it may be necessary to remove the heat exchanger completely for cleaning. The simplest method is steam cleaning at the local car wash. DO NOT WIREBRUSH.
COMBUSTIONCHAMBERREMOVAL
To remove combustion chamber, you must first have removed the heat exchanger. Unbolt metal combination chamber retainer from top and remove combustion chamber panels individually.
REFACTORY PANELS TOP VIEW
CONTROL IMMERSION WELL REPLACEMENT Removetop,sensingbulbandclip. Collapsewelltube
at the open end with a chisel, push through into header and remove the header. Insert a new well and roll into place. If a roller is not available, solder.
IMMERSION WELL
Fig. # 8126.0
UNITHERMGOVERNOR(U.G.)REPLACEMENT
1.Shut water, gas and electricity off, close valves and relieve pressure.
2.Drain heat exchanger.
3.Loosen and remove (2) bolts that secure U.G. Assembly to header.
4.Remove U.G. Assembly with gasket.
5.Reverse above procedure to
INLET/OUTLET
HEADER
| UNITHERM |
U.G. GASKET | GOVERNOR |
| Fig. #8224.0 |
To test the operation of the Unitherm Governor, place in hot water (over 100°F) and watch for movement against spring. If there is not movement, replace unit.
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