Modine Manufacturing 6-558.6 - Manual (Page 25)

SERVICE INSTRUCTIONS — GENERAL
TROUBLESHOOTING GUIDE
Only people trained and familiar with the operation of unit
heaters and their controls should service this unit.
General Maintenance
1. Service air moving components annually.
a. On propeller units this includes checking motor for
lubrication if motor is not there permanently lubricated
type and check fan for fit on motor shaft and for
damage to blades.
b. On blower units this should include:
(1) checking motor and blower bearings for lubrication
(2) checking belt and sheaves for proper alignment and
adjustment
(3) checking cleanliness of blower wheel and filters
2. Keep unit free from dust, dirt, grease and foreign matter,
paying particular attention to:
a. Combustion air inlet terminal.
b. Main burner ports, pilot burner, an main burner orifices
(avoid use of hard, sharp instruments capable of
damaging surfaces, for cleaning these ports). If air
pressure is available, use air hose to blow dirt and
other foreign matter from within the burner. Also main
burner orifices should be checked for blockage due to
spider webs, etc.
c. Primary air shutters (when used).
d. Clean heat exchanger tubes from bottom with stiff
brush after removing burner. (Do not use wire brush.)
e. Fan blades.
To Remove Main Burner
1. Turn off electricity and gas to unit.
2. Remove access panel (see Figure 13).
3. Remove all fastening screws holding hinged bottom pan in
place and lower bottom pan (see Figure 2).
4. Disconnect pilot tubing and ignition cable from the
combination gas control and ignition control.
5. Remove the two burner retaining pins holding the burner in
place. The burner can then be easily lowered from the unit.
In replacing the burner, be certain that the slots at the front
of the burner are located properly on their shoulder rivets
and that the burner retaining pins are put back into their
proper locations.
Replace bottom pan and access panel, making sure a good
tight seal is achieved along he entire perimeter of both
panels.
Figure 14
Manifold Adjustment
Combustion Diagnosis
To realize full gas heating value requires periodic inspections
with proper combustion control corrections as outlined and
illustrated here.
1. Lifting Flames. Lifting flames rise unevenly above the
burner port and may occur on few or all the ports.
Sometimes the flames drop and lift intermittently. Lifting can
be eliminated by reducing primary air. If flame cannot be
adjusted properly, check input rate to heater and manifold
gas pressure; reduce if necessary. Check the main burner
orifice size with those listed in Table 5 to be sure the unit is
not operating over rated input.
Figure 15
Air Shutter Adjustment, Propane Gas
Figure 16
Lifting Flame Condition
25
MIXER
TUBES
PRIMARY
AIR SHUTTER
MAIN
BURNER ORIFICE
MANIFOLD
COMBUSTION
AIR INLET COLLAR
PILOT
TUBE
MANIFOLD
PILOT AND
IGNITOR
ASSEMBLY
HINGED BOTTOM PAN
MAIN BURNER
ORIFICE
MIXER
TUBES
MANIFOLD
MOUNTING
SCREW
IGNITION
CABLE
IGNITION CONTROL
Heater Parts from ACF Greenhouses