Desa and 55 Nozzle, Pump Rotor, Procedure if Rotor is Binding, sure Adjustment, page, Continued

35,000, 50,000, And 55,000 Btu/Hr H.S.I. Series

PORTABLE FORCED AIR HEATERS

SERVICE

PROCEDURES

Continued

NOZZLE

1.	Remove upper shell (see page 6).
2.	Remove fan (see page 6).
3.	Remove fuel and air line hoses from
	nozzle assembly (see Figure 11).
4.	Turn nozzle adapter 1/4 turn to left and

Combustion

Chamber

Nozzle
Adaptor	Nozzle
Bracket
	Adapter

Nozzle Face

Nozzle Seal

Nozzle

Nozzle Adapter

Air Line

Fitting

Fuel Line Fitting

Figure 13 - Nozzle and Nozzle Adapter

	pull toward motor to remove (see Fig-
	ure 13).
5.	Place nozzle adapter into vise and
	lightly tighten.
6.	Carefully unscrew nozzle from the
	nozzle adapter using 5/8" socket
	wrench (see Figure 14).
7.	Blow compressed air through face of
	nozzle. This will free any dirt in
	nozzle area.
8.	Inspect nozzle seal for damage.
9.	Replace nozzle into nozzle adapter un-

Figure 12 - Removing Nozzle Assembly

PUMP ROTOR

(Procedure if Rotor is Binding)

1.	Remove upper shell (see page 6).
2.	Remove filter end cover screws using
	5/16" nut-driver.
3.	Remove filter end cover and air filters.
4.	Remove pump plate screws using 5/16"
	nut-driver.
5.	Remove pump plate.

Insert

Blade

Pump Plate

Air Intake Filter

Filter End

Cover

Rotor

Air Output

Filter

Fan Guard

	til nozzle seats. Tighten 1/3 turn more
	using 5/8" socket wrench (40-45 inch-
	pounds).
10.	Attach nozzle assembly to burner strap.
11. Attach and route fuel and airline hoses
	to nozzle assembly as shown (see Fig-
	ure 11). Route photocell wires as shown
	in Figure 11.
12.	Replace fan (see page 6).
13.	Replace fan guard and upper shell (see
	page 6).

Combustion

Chamber

Nozzle/

Adapter

Assembly

Photocell

Wires

Air Line Hose

Fuel Line

Hose

Figure 11 - Removing Air and Fuel Line Hoses

6.	Remove rotor, insert, and blades.
7.	Check for debris in pump. If debris is
	found, blow out with compressed air.
8.	Install insert and rotor.
9.	Check gap on rotor. Adjust to .003"/.004"
	if needed (see Figure 15).
	Note: Rotate rotor one full turn to in-
	sure the gap is .003"/.004" at tightest
	position. Adjust if needed.
10.	Install blades, pump plate, air filters,
	and filter end cover.
11.	Replace fan guard and upper shell.
12.	Adjust pump pressure (see Pump Pres-
	sure Adjustment, page 6).
	Note: If rotor is still binding, proceed
	as follows.
13.	Perform steps 1 through 6 above.
14.	Place fine grade sandpaper (600 grit) on
	flat surface. Sand rotor lightly in “figure
	8” motion four times (see Figure 16).
15.	Reinstall insert and rotor.
16.	Perform steps 10 through 12 above.

Figure 14 - Rotor Location

Gap Adjusting Screw

.003"/.004" Gap Measured With Feeler Gauge

Rotor

Blade

Gap Adjusting

Screw

Figure 15 - Gap Adjusting Screw Locations

Sandpaper

Figure 16 - Sanding Rotor

8 102388