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4. Take garden hose and wash heat exchanger, mak-
ing sure soot is removed from between fins. (Avoid
excessive water against refractory).
5. Reassemble; when heater is fired, some steam will
form from wet refractory. This is normal.
Unitherm Governor
Replacement
1. Shut off water, gas and electricity, close valves,
relieve pressure.
2. Drain heat exchanger.
3. Remove Unitherm Governor.
To test operation of Unitherm Governor, place in hot
water (110°F or higher) and watch for movement
against spring. If no movement, replace.
NOTE: In extreme cases it may be necessary to
remove the heat exchanger completely for cleaning.
The simplest method is steam cleaning at a local car
wash. DO NOT WIRE BRUSH!
CAUTION: Soot is combustible, so exercise
extreme care.
INLET/OUTLET HEADER
OUTLET
INLET
GASKET
UNITHERM GOVERNOR
WITH POWER ELEMENT
Fig. 38: Unitherm Governor—Models 926–1223
MAINTENANCE AND
CARE
T
o be followed one month after initial start-up and then
quarterly.
1. Inspect top of heater and draft-hood for soot, and
open fuel gas passageways.
2. Clean main burners and pilot burner of dust and
lint.
3. Inspect and operate all controls and gas valve.
4. Make visual check of burner and pilot flame.
Flame pattern on main burner and pilot is indicat-
ed on page 26. Yellow flame means restriction of
air openings. Lifting or blowing flame indicates
high gas pressure. Low flame means low gas
pressure.
5. Clean room air intake openings to ensure ade-
quate flow of combustion and ventilation air.
6. Remove header opposite inlet pipes when clean-
ing and inspect internal tubes for scale deposits. If
scale does not form within first quarterly inspec-
tion, then inspect annually thereafter.
7. Keep heater air clear and free from combustible
materials and other flammable and corrosive
vapors and liquids.
8. Keep moving parts lubricated.
9. Manual operation of pressure/temperature relief
valve at least once a year.
CAUTION: Soot may be combustible. Wet com-
pletely when cleaning.
CAUTION: Combustion air must not be
contaminated by corrosive chemical fumes which
can damage the heater and void the warranty.