H I G H P R E S S U R E P O R T A B L E F O R C E D A I R H E A T E R S E R V I C E M A N U A L
22
TROUBLESHOOTING — PROBLEM CONDITIONS
OBSERVED PROBLEM
Carbon build-up inside combustion chamber
POSSIBLE CAUSE
A. High altitude
B. Incorrect fuel pump pressure
C. Wrong fuel
D. Restricted air flow to heater
TEST PROCEDURES
A. High Altitude
All heaters are designed and tested for use at
elevations less than 3,000 feet above sea
level. Using heater at altitudes higher than
3,000 feet above sea level results in an
unbalance in the air/fuel mixture. Air is less
dense at higher altitudes. This causes the
unbalance in the air/fuel mixture. This unbal-
ance may result in carbon build-up inside
combustion chamber.
If heater has been used at elevations above
3,000 feet, follow the instructions below to
correct carbon build-up. If heater has been
used at elevations below 3,000 feet, check
for other possible causes listed above.
600,000 BTU/Hr Model
1. Remove upper shell of heater.
2. Remove burner head orifice if heater is
equipped with one (see Figure 32).
3. Replace existing nozzle with a 3.5 gph,
70 degree, type A, hollow-spray-pattern
nozzle (DESA part number M14969).
Figure 32 - Burner Head and Head Orifice
4. Check pump pressure. Make sure pump
pressure is 110 psi.
Note: Reinstall original nozzle and burner
head orifice (if heater was equipped with
one) if moving heater to lower altitudes.
350,000 BTU/Hr Model
1. Remove upper shell of heater.
2. Remove burner head orifice if heater is
equipped with one (see Figure 32).
3. Replace existing nozzle with a 2.25 gph,
80 degree, type A, hollow-spray-pattern
nozzle (DESA part number M22626).
4. Check pump pressure. For 350,000 BTU/
Hr model, high altitude pump pressure
must be 110 psi.
Note: Reinstall original nozzle and burner
head orifice (if heater was equipped with
one) if moving heater to lower altitudes.
B. Incorrect fuel pump pressure
Follow steps under INCORRECT FUEL PUMP
PRESSURE, procedure “C” on page 13.
C. Wrong fuel
Use proper fuel. See GENERAL SPECIFI-
CATIONS AND APPLICATIONS INFORMA-
TION on page 5 for fuel guidelines.
D. Restricted air flow to heater
Make sure air flow to air inlet (rear) of heater
is not blocked. Less air entering rear of
heater will result in an unbalance in the air/
fuel mixture. This unbalance may result in
carbon build-up inside combustion chamber.
Burner Head
Orifice
